Bio/Biochem Flashcards
(529 cards)
1
Q
What is a peptide hormone?
A
Chemical precursor = amino acids, location of receptor = extracellular, mechanism of action = initiates a signal cascade, method of travel in the bloodstream = dissolves freely, speed of onset = quick, duration of action = short-lived
2
Q
What is a steroid hormone?
A
Chemical precursor = cholesterol, location of receptor = intracellular/intranuclear, mechanism of action = binds to a receptor and induces conformational change, method of travel in the bloodstream = binds to a carrier protein, speed of onset = slow, duration of action = long-lived
3
Q
What is a direct hormone?
A
Direct hormones are secreted into the bloodstream, has a direct effect on a target tissue
4
Q
What is a tropic hormone?
A
Tropic hormones cause secretion of another hormones that then travels to the target tissue to cause an effect (“FLAT” in “FLAT PEG”)
5
Q
What is the hormone from the anterior pituitary/target organ does CRF affect?
A
Corticotropin-releasing factor (CRF) affects the ACTH hormone in the anterior pituitary, which affects the adrenal cortex, which releases glucocorticoids (cortisol and cortisone) from the adrenal cortex
6
Q
Which endocrine tissue synthesizes catecholamines?
A
Adrenal medulla, which produces epinephrine and norepinephrine
7
Q
What is aldosterone?
A
Aldosterone increases sodium reabsoprtion in the distal convoluted tubule and collecting duct of the nephron (increases blood volume and pressure)
8
Q
What is ADH?
A
ADH increases water reabsorption and decreases plasma osmolarity in collecting ducts (without ADH, collecting duct is almost impermeable to water) - increases blood pressure and volume due to increased volume
9
Q
What is ANP?
A
ANP increases glomerular filtration (lowers blood pressure)
10
Q
Which muscles are involved in inhalation? Exhalation?
A
The external intercostal muscles and diaphragm are involved in inhalation, the external intercostal muscles are involved in exhalation
11
Q
If blood levels of CO2 become too low, how does the brain alter the respiratory rate to maintain homeostasis?
A
The brain decreases its respiratory rate to increase CO2
12
Q
What are some of the mechanisms used in the respiratory system to prevent infection?
A
Vibrissae in the nares, lysozyme in the mucous membranes, the mucociliary escalator, macrophages in the lungs, mucosal IgA antibodies, and mast cells
13
Q
Increased synthetic activity of the parathyroid glands would lead to:
A
An increase in renal calcium reabsorption
14
Q
Iodine deficiency may result in:
A
Cretinism
15
Q
Which hormones listed are steroid/peptide hormones? (Aldosterone, Estrogen, Oxytocin, Progesterone)
A
Aldosterone, Estrogen, Progesterone = Steroid hormones, Oxytocin = Peptide hormone
16
Q
What is a fact about pancreatic somatostatin?
A
It is always inhibitory
17
Q
A blocking of dopamine receptors would cause:
A
Increased secretion of prolactin
18
Q
A female born with ambiguous genitalia and low sodium concentration would affect:
A
Adrenal cortex
19
Q
What makes up the intrapleural space?
A
The parietal pleura and the visceral pleura
20
Q
How would the stiffening of the lung tissue affect the body?
A
Decreased inspiratory reserve volume
21
Q
If mucus or pus built up within an entire lobe of the lung, how would this affect diffusion of gas?
A
No diffusion would occur in the affected area
22
Q
What does hyperventilation cause?
A
A decrease in blood carbon dioxide, so breathing air from a bag helps to readjust blood levels of carbon dioxide
23
Q
What is the point of using positive end-expiratory pressure for premature infants?
A
Prevent alveoli from collapsing on each other (similar to the point of surfactant)
24
Q
What is a mast cell?
A
A mast cell is what is attached to an antibody, can release inflammatory mediators that cause allergic reactions
25
What is a nucleoside?
Five-carbon sugar (pentose) and nitrogenous base
26
What is a nucleotide?
Five-carbon sugar (pentose), nitrogenous base, and one to three phosphate groups
27
What are the base-pairing rules according to the Watson-Crick model?
A pairs with T/U using two hydrogen bonds, C pairs with G using three hydrogen bonds
28
How does the aromaticity of purines and pyrimidines underscore their genetic function?
Aromatic = stable and unreactive (stability is important for stroing genetic information and avoiding spontaneous mutations)
29
If a strand of RNA contained 15% cytosine, 15% adenine, 35% guanine, and 35% uracil, would this violate Chargaff's rules?
This would not violate Chargaff's rules because the complimentarity seen in DNA does not hold true (should have a 1:1 ratio of purines and pyrimidines)
30
What is helicase?
Unwinds DNA double helix, present in prokaryotes and eukaryotes
31
What is single-stranded DNA-binding protein?
Prevents reannealing of DNA double helix during replication, present in prokaryotes and eukaryotes
32
What is DNA polymerase III?
Adds nucleotides to growing daughter strand (synthesizes DNA), present in prokaryotes
33
What is DNA polymerase alpha?
Adds nucleotides to growing daughter strand (synthesizes DNA), present in eukaryotes
34
What is DNA polymerase I?
Fills in gaps left behind after RNA primer excision (removes RNA primers, replaces RNA with DNA), present in prokaryotes
35
What is RNAse H?
Excises RNA primer, present in eukaryotes
36
What is DNA ligase?
Joins DNA strands (especially between Okazaki fragments)
37
Between the leading and lagging strand, which is more prone to mutations?
Lagging strand because it constantly starts and stops the process of DNA replication, and it contains many more RNA primers
38
What are telomeres?
Telomeres are the ends of eukaryotic chromosomes and contain repetitive sequence of noncoding DNA, they protect the chromosome from losing important genes from the incomplete replication of the 5' end of the DNA strand
39
What is an oncogene?
Oncogenes code for cell cycle-promoting proteins
40
What is a tumor suppressor gene?
Tumor suppressor genes code for repair or cell-cycle inhibiting proteins
41
What is the difference between the parent strand and the daughter strand?
The parent strand is more heavily methylated, and the daughter strand is barely methylated at all
42
Give some information about DNA polymerase (proofreading).
Involved in S phase of cell cycle, key enzyme/gene = DNA polymerase
43
Give some information about mismatch repair.
Involved in G2 phase of cell cycle, key enzymes/genes = MSH2, MLH1 (MutS and MutL in prokaryotes)
44
Give some information about nucleotide excision repair.
Involved in G1 and G2 phases of cell cycle, key enzymes/genes = excision endonuclease
45
Give some information about base excision repair.
Involved in G2 and G2 phases of cell cycle, glycosylase, AP endonuclease
46
What is a genomic library?
Genomic libraries include all of the DNA in an organism's genome, including noncoding regions (useful for studying introns, centromeres, telomeres)
47
What is a cDNA library?
cDNA libraries only include expressed genes from a given tissue, but can be used to express recombinant proteins or to perform gene therapy
48
What is PCR?
PCR increases the number of copies of a given DNA sequence and can be used for a sample containing very few copies of the DNA sequence
49
What is Southern blotting?
Southern blotting searches for a particular DNA sequence
50
During DNA sequence, why does the DNA polymer stop growing once a dideoxyribonucleotide is added?
Dideoxyribonucleotide lacks the 3' -OH that is required for DNA strand elongation
51
What is a transgenic mouse?
Transgenic mice have a gene introduced into their germ line or embryonic stem cells to look at the effects of that gene
52
What is a knockout mouse?
Knockout mice are those in which a gene of interest has been removed
53
Which of the following biomolecules is LEAST likely to contin an aromatic ring?
Carbohydrates
54
For a compound to be aromatic:
The molecule is cyclic, contains 4n + 2pi electrons, and planar
55
Restriction endonucleases are used for which of the following?
Gene therapy, southern blotting, and DNA repair
56
Why might uracil be excluded from DNA but NOT RNA?
Cytosine degradation results in uracil
57
What is mRNA?
a single-stranded RNA molecule that corresponds to the genetic sequence of a gene
58
What is tRNA?
tRNA translates nucleic acids to amino acids by pairing its anticodon with mRNA codons
59
What is rRNA?
rRNA forms much of the structural and catalytic component of the ribosome, acts as a ribozyme to create peptide bonds between amino acids
60
What does RNA polymerase I do?
RNA polymerase I synthesizes most rRNA
61
What does RNA polymerase II do?
RNA polymerase II synthesizes mRNA (hnRNA) and snRNA, binds to the TATA box
62
What does RNA polymerase III do?
RNA polymerase III synthesizes tRNA and some rRNA
63
What is alternative splicing?
Alternative splicing is the ability of some genes to use various combinations of exons to create multiple proteins from one hnRNA transcript
64
What occurs in the A site?
Binds incoming aminoacyl-tRNA using codon-anticodon pairing
65
What occurs in the P site?
Holds growing polypeptide until peptidyl transferase forms peptide bond and polypeptide is handed to A site
66
What occurs in the E site?
Transiently holds uncharged tRNA as it exits the ribosome
67
What are some of the posttranslational modifications?
Proper folding by chaperones, formation of quaternary structure, cleavage of proteins or signal sequences, and addition of other biomolecules
68
What type of operon is the trp operon? The lac operon?
The trp operon is a negative repressible system, the lac operon is a negative inducible system
69
What is the regulator gene?
Transcribed to form repressor protein
70
What is the promoter site?
Site of RNA polymerase binding (similar to promotes in eukaryotes)
71
What is the operator site?
Binding site for repressor protein
72
What is the structural gene?
The gene of interest; its transcription is dependent on the repressor being absent from the operator site
73
What is the relationship between signal molecules, transciption factors, and response elements?
Signal molecules are transcription factors that use their DNA-binding domain to attach to a response element so that the transcription factors can increase expression of the relevant gene
74
Do histone deacetylation and DNA methylation up or downregulate transcription?
Downregulate, increasing proportion of heterochromatin
75
What role does peptidyl transferase play in protein synthesis?
It catalyzes the formation of a peptide bond
76
Enhancers are transcriptional regulatory sequences that function by enhancing the activity of:
RNA polymerase at a single promoter site
77
What are the four chambers of the heart and their valves?
Right atrium = tricuspid valve, right ventricle = pulmonary valve, left atrium = mitral (bicuspid) valve, left ventricle = aortic valve
78
What are arteries?
Carries blood away from heart, thick walls, a lot of smooth muscle, does not contain valves
79
What are capillaries?
Carries blood from arterioles to venules, very thin walls, no smooth muscle present, does not contain valves
80
What are veins?
Carries blood towards the heart, thin walls, a little of smooth muscle present, does contain valves
81
Why does the right side of the heart contain less cardiac muscle than the left side?
The right side of the heart pumps blood into a lower-resistance circuit at a lower pressure, so it requires less muscle
82
If all autonomic input to the heart were cut, what would happen?
The heart would continue beating at the intrinsic rate of the pacemaker (SA node), the individual would be able to change his or her heart rate
83
What are the components of plasma?
Plasma is an aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins
84
If an individual with B+ was in an accident, who could the person receive/donate blood to?
Could receive from O+, O-, B+, B- ; could donate to B+, AB+
85
What does a hematocrit measure?
Hematocrit meausres the percentage of a blood sample occupied by red blood cells
86
What types of leukocytes are involved in the specific immune response?
Lymphocytes
87
Where do platelets come from?
Cellular fragments or shards that are given off by megakaryocytes in the bone marrow
88
Which cell types contain/ do not contain nuclei?
Leukocytes contain nuclei, erythrocytes and platetes do not contain nuclei
89
If capillary beds open in the body, how will that affect blood pressure?
Capillaries open -> less resistance -> raise heart rate -> dangerous
90
What direction does the oxyhemoglobin dissociation curve shift as a result of exercise?
The oxyhemoglobin curve shifts to the right during exercise in response to increased arterial CO2, increased H+, decreased pH, and increased temperature (decreased affinity for oxygen)
91
Exposure of which subendothelial compounds start the coagulation cascade? Which protein helps stabilize the clot?
Cascade started by exposure to platelets and coagulation factors, clot is stabilized by fibrin
92
Which of the following is the correct sequence of a cardiac impulse?
SA node -> atria -> AV node -> bundle of His -> Purkinje fibers -> ventricles
93
Hemoglobin's affinity for O2:
Decreases as blood pH decreases
94
Which of the following is true regarding arteries and veins?
The blood pressure in the aorta is always higher than the pressure in the superior vena cava
95
At any time, there is more blood in the venous system than the arterial system. Which of the following features of veins allows for this?
Relative lack of smooth muscle in the wall
96
Where is the bundle of His located?
In a wall between the two ventricles
97
What is innate immunity?
Defenses that are always active against pathogens, but that are not capable of targeting specific invaders
98
What is adaptive immunity?
Takes longer to achieve a response, but that response targets a specific pathogen and maintains immunologic memory of the infection to mount a faster response during subsequent infections
99
What are B-cells?
Site of development = bone marrow, matures in bone marrow, produces antibodies, specific, humoral response
100
What are T-cells?
Site of development = bone marrow, matures in thymus, specific, cell-mediated response (helper = secrete cytokines, stimulates B-cells to become plasma cells), help maturate B cells, cytotoxic = kill virus-infected cells)
101
Which cells are considered granulocytes?
Neutrophils, eosionphils, basophils
102
Which cells are considered agranulocytes?
B-cells, T-cells (lymphocytes), and monocytes (macrophages)
103
What is skin's immune defense?
Provides a physical barrier and secretes antimicrobial enzymes
104
What is defensins' immune defense?
An example of antibacterial enzymes on the skin
105
What is lysozyme's immune defense?
Antimicrobial, present in tears and saliva
106
What is mucus' immune defense?
Present on mucous membranes, traps incoming pathogens
107
What is stomach acid's immune defense?
An antimicrobial substance in the digestive system
108
What is normal gastrointestinal flora's immune defense?
Provides competition, making it hard for pathogenic bacteria to grow in the gut
109
What is complement's immune defense?
A set of proteins in the blood that can create holes in bacteria
110
Which cells are professional antigen-presenting cells?
Some B-cells, macrophages, dendritic cells, certain activated epithelial cells
111
What is the difference between MHCI and MHCII?
MHC-I is found is all nucleated cells and presents pieces of proteins (peptides) created within the cell (endogenous antigens); MHC-II is only found in antigen-presenting cells and presents proteins that result from the digestion of extracellular pathogens that have been brought in by endocytosis (exogenous antigens)
112
What stimulus activates natural killer cells?
Cells that do not present MHC
113
What stimulus activates neutrophils?
Bacteria, especially those that have been opsonized (tagged with an antibody on their surface)
114
What stimulus activates eosinophils?
Invasive parasites and allergens
115
What stimulus activates basophils and mast cells?
Allergens
116
What is the function of a plasma cell?
Form from B-cells exposed to antigen and produce antibodies
117
What is the function of a memory B-cell?
Form from B-cells exposed to antigen, lie in wait for a second exposure to a given antigen to mount a rapid, robust response
118
What is the function of a helper T-cell?
Coordinate the immune system through lymphokines and respond to antigen bound to MHC-II (one of the most important cells for adaptive response, activate B cells, macrophages and cytotoxic T cells)
119
What is the function of a cytotoxic T-cell?
Kill virally infected cells and respond to antigen bound to MHC-I
120
What is the function of a suppressor (regulatory) T-cell?
Keep the immune system from becoming overactive, promote self-tolerance
121
What is the functional of a memory T-cell?
Lie in wait until a second exposure to a pathogen to mount a rapid, robust response
122
What are the three main effects circulating antibodies can have on a pathogen?
Mark a pathogen for destruction by phagocytic cells (opsonization), cause agglutination of the pathogen into insoluble complexes that can be taken up by phagocytic cells, or neutralize the pathogen by preventing it from invading tissues
123
How do antibodies become specific for a given antigen?
B-cells that have the highest affinity for an antigen survive and proliferate, increasing their specificity
124
A T-cell appropriately passes through positive selection, but then inappropriately passes through negative selection. What will this T-cell be reactive towards?
Positive selection = T-cells in the thymus that are able to respond to antigen presented on MHC are allowed to survive, negative selection = T-cells that respond to self-antigens undergo apoptosis before leaving the thymus (negative selection = reactive to self-antigens)
125
Which cells account for the fact that the secondary response to a pathogen is much more rapid and robust than the primary response?
Memory cells
126
What is active immunity?
Stimulation of the immune system to produce antibodies against a pathogen
127
What is passive immunity?
The transfer of antibodies to prevent infection, wihtout stimulation of the plasma cells that producte these antibodies
128
If an individual had a blockage of lymph node flow, what would likely happen?
Edema, severe swelling of the limb, thickening of the skin
129
What structure is primarily responsible for returning materials from lymphatic circulaton to the cardiovascular system?
Thoracic duct, carries lymphatic fluid into the left subclavian vein
130
The absence of the thymus would leave an individual unable to mount specific defenses against which of the following types of pathogens?
Viruses (T-lymphocytes defend against intracellular pathogens)
131
What are some types of cells involved in cell-mediated immunity?
Memory cells, cytotoxic cells, suppressor cells
132
The lymphatic system:
Transports chylomicrons (fats) to the circulatory system, produce immune cells, remove excess fluids
133
Which type of cells is involved in antibody production?
Plasma cells
134
What are some examples of nonspecific defense mechanisms?
Skin provides a physical barrier against invasion, macrophages engulf and destroy foreign particles, an inflammatory reponse is initiated in response to physical damage
135
What is an example of adaptive immunity?
Memory B-cells generated through vaccination are activated when their antigen is encountered
136
What is a true statement about active and passive immunity?
Active immunity requires weeks to build, whereas passive immunity is acquired immediately
137
Where are most self-reactive T-cells eliminated?
Thymus
138
What is the response of the immune system to downregulation of MHC molecules on somatic cells?
Natural killer cells induce apoptosis of affected cells
139
What is the response of CD8+ T-cells when activated?
Secretion of cytotoxic chemicals
140
What cells are likely to cause lymphoma?
CD8+ T-cells, B-cells, and Th1 cells (Helper T-cells)
141
Upon encountering an antigen, only T-cells with a specific T-cell receptor are activated. This is an example of:
Clonal selection
142
Which cell type is a phagocyte that attacks bacterial pathogens in the bloodstream?
Neutrophils
143
Which type of immunity is likely to be affected by removal of the spleen?
Humoral immunity (spleen is where B-cells are made and proliferated)
144
What cell types are granulocytes?
Mast cells, eosinophils, basophils
145
What is the stereochemistry of the chiral amino acids that appear in eukaryotic proteins?
All are S except for cysteine
146
How to calculate pI
Basic amino acid = two basic pKa values (amino and side chain), acidic amino acid = two acidic pKa values (carbonyl and side chain)
147
What is the primary structure?
Linear sequence of amino acids in chain, stabilized by peptide (amide) bonds
148
What is the secondary structure?
Local structure determined by nearby amino acids, subtypes = alpha helix, beta sheet (bonds between carbonyl oxygen and amide hydrogen), stabilized by hydrogen bonds
149
What role does proline serve in secondary structure?
Proline's rigid structure causes it to introduce kinks in a helix or create turns in B sheets
150
What is the tertiary structure?
3D shape of protein, subtypes = hydrophobic interactions, acid-base/salt bridges, disulfide links, stabilized by van der Waals forces, hydrogen bonds, ionic and covalent bonds
151
What is the quaternary structure?
Interaction between separate subunits of a multisubunit protein, stabilized by van der Waals forces, hydrogen bonds, covalent and ionic bonds
152
What are examples of common prosthetic groups?
Lipids, carbohydrates, and nucleic acids
153
How does heat and solutes denature proteins?
Heat denatures proteins by increasing their average KE, disrupting hydrophobic interactions, whereas solutes denature proteins by disrupting elements of secondary, tertiary, and quaternary structure
154
In a neutral solution, most amino acids exist as:
zwitterions
155
How many distinct tripeptides can be formed from one valine, one alanine, and one leucine?
6
156
Which amino acids have a chiral carbon in its side chain?
Threonine and Isoleucine
157
What are some reasons for conjugating proteins?
To direct their delivery to a particular organelle, to direct their delivery to the cell membrane, and to add a cofactor needed for their activity
158
If there is a tightly wrapped "triple helix", which amino acid is likely to be found in the highest concentration?
Glycine
159
What is the function of ligase?
Addition or synthesis reactions, generally between large molecules; often require ATP
160
What is the function of isomerase?
Rearrangement of bonds within a compound
161
What is the function of lyase?
Cleavage of a single molecule into two products, or synthesis of small organic molecules
162
What is the function of hydrolase?
Breaking of a compound into two molecules using the additon of water
163
What is the function of oxidoreductase?
Oxidation-reduction reactions
164
What is the function of transferase?
Movement of a functional group from one molcule to another
165
What is the lock and key theory?
Active site of enzyme fits exactly around substrate, no alterations to tertiary/quaternary structure, less accurate
166
What is the induced fit model?
Active site of enzyme molds itself around substrate only when substrate is present, tertiary and quaternary strucutre is modified for enzyme to function, more accurate model
167
What does increasing substrate and enzyme concentration do to Vmax?
Increasing S increases enzyme activity until enzyme is saturated, increasing E will always increase Vmax
168
What is Km?
Km is a measure of the enzyme's affinity for its substrate, as Km increases, an enzyme's affinity for its substrate decreases
169
What is cooperativity?
Cooperativity are the interactions between subunits in a multisubunit enzyme or protein
170
What is the ideal temperature/pH for enzymes?
37 degrees C/98.6 F/310 K, 7.4 (2 for gastric enzymes, 8.5 for pancreatic enzymes)
171
What is feedback inhibition?
The product of an enzymatic pathway turning off enzymes further back in that same pathway
172
Why does competitive inhibition increase Km?
The substrate concentration has to be higher to reach half the maximum velocity in the presence of the inhibitor
173
Why does mixed inhibition increase Km?
Mixed inhibition will only increase Km if the inhibitor preferentially binds to the enzyme over the enzyme-substrate complex
174
What is irreversible inhibition?
The prolonged or permanent inactivation of an enzyme, such that it cannot be easily renatured to gain function
175
What are examples of transient/covalent modifications?
Examples of transient modifications include allosteric activation and inhibition. Examples of covalent modifications include phosphorylation and glycosylation.
176
What are zymogens?
Precursors of active enzymes, it is critical that certain enzymes (like the digestive enzymes of the pancreas) remain inactive until arriving at their target site
177
The conversion of ATP to cAMP and inorganic phosphate is most likely catalyzed by which class of enzyme?
Lyases
178
How do enzymes decrease the activation energy for biological reactions?
Modifying the local charge environment, forming transient covalent bonds, an acting as electron donors and receptors
179
Why is triaglycerol not likely to act as a coenzyme?
Large size, neutral charge, ubiquity in cells
180
How does the ideal temperature for a reaction change with and without an enzyme catalyst?
The ideal temperature is generally lower with a catalyst than without
181
What is the difference between mechanical and chemical digestion?
Mechanical digestion = physically breaking down food into smaller pieces, Chemical digestion = hydrolysis of bonds and breakdown of food into smaller biomolecules
182
What two main enzymes are found in saliva?
Salivary amylase (digests starch into smaller sugars) and lipase (digests fats)
183
What are mucous cells?
Secretes mucus, protects lining of stomach, increases pH (bicarbonate)
184
What are chief cells?
Secretes pepsinogen, digests proteins (activated by H+)
185
What are parietal cells?
Secretes HCl (decreases pH, kills microbes, denatures proteins, carries out some chemical digestion) and intrinsic factor (absorbs vitamin B12)
186
What are G-cells?
Secretes gastrin, increases HCl production, increases gastric motility
187
What is sucrase?
Brush border enzyme; breaks down sucrose into monosaccharides
188
What is secretin?
FIREMAN - Increases pancreatic secretions, especially bicarbonate to response to acid; reduces HCl secretion; decreases motility
189
What is dipeptidase?
Brush border enzyme; breaks down dipeptides into free amino acids
190
What is cholecystokinin?
Recruits secretions from gallbladder and pancreas; promotes satiety
191
What is enteropeptidase?
Produced in the duodenum, digests food, activates trypsinogen (zymogen), which initiates an activation cascade
192
How do bile and pancreatic lipase work together to digest fats?
Bile mechanically digests fats, pancreatic lipase chemically digests fats
193
What are some pancreatic enzymes that breakdown carbohydrates, proteins, and fats?
Carbohydrates: pancreatic amylase; proteins: trypsin, chymotrypsin, carboxypeptides A and B; fats: pancreatic lipase
194
What are the main components of bile?
Bile salts, pigments (bilirubin), and cholesterol
195
Where is bile synthesized, stored, and where does it carry out its digestive function?
Synthesized in the liver, stored in the gallbladder and serves its function in the duodenum
196
What are some functions of the liver?
Processes nutrients (esp. glycogenesis and gluconeogenesis), storage and mobilization of fats, activates/inactivates medications, produces bile, synthesizes albumin and clotting factors
197
What are the two circulatory vessels in a villus and what biomolecules are absorbed in each?
Capillaries (absorb water-soluble nutrients), lacetals (absorb fat-soluble molecules)
198
Which two organs digest proteins?
Stomach and small intestine
199
What would an elevated bilirubin level cause?
Blockage to bile flow, increased production of bilirubin (from massive hemoglobin release), or an inability of the liver to produce bile
200
Starch is hydrolyzed into maltose by enzymes from the:
Salivary glands and pancreas (salivary amylase and pancreatic amylase)
201
Which compounds do not pass through the liver before reaching the right heart
Fat-soluble compounds
202
List the vessels in the renal vascular pathway, starting from the renal artery and ending in the renal vein
Renal artery -> afferent arteriole -> glomerulus -> efferent arteriole -> vasa recta -> renal vein
203
What arm of the nervous system is responsible for contraction of the detrusor muscle?
Parasympathetic
204
What occurs in filtration?
Movement of solutes from blood into filtrate at Bowman's capsule
205
What occurs in secretion?
Movement of solutes from blood into filtrate anywhere besides Bowman's capsule
206
What occurs in reabsorption?
Movement of solutes from filtrate into blood
207
What is the predominant cell type in the epidermis?
Keratinocytes
208
What are the layers of the epidermis, from superficial to deep?
Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale (Come, Let's Get Sun Burned) - lucidum is not found everywhere in the epidermis
209
What are the layers of the dermis, from superficial to deep?
Papillary layer, reticular layer
210
What are some mechanisms the body uses to cool itself/retain heat?
Cooling = sweating vasodilation, retain heat = vasoconstriction, piloerection, shivering
211
In which of the following segments of the nephron is sodium NOT actively transported out of the nephron?
Thin portion of the ascending limb of the loop of Henle
212
In the nephron, amino acids enter the vasa recta (blood vessels in kidney) via the process of:
reabsorption
213
Under normal physiologal circumstances, the primary function of the nephron is to create urine that is:
Hypertonic to the blood
214
A laceration cuts down into a layer of loose connective tissue in the skin. Which layer of the skin is this?
Papillary layer
215
When the pH of the blood is high, which substance is likely to be excreted in larger quantities in the urine?
Bicarbonate ions
216
A drug is used that prevents the conversion of angiotensin I to angiotensin II. What is a likely effect of this drug?
Increased potassium reabsorption
217
If a drug caused excessive buildup of acetylcholine in all synapses where it is the neurotransmitter, what symptoms would arise?
Increased urination and increased sweating
218
What is GLUT2?
Important in liver and pancreas, Km = high (15 mM), is not saturated at normal glucose levels, is not responsive to insulin (can serve as glucose sensor)
219
What is GLUT4?
Important in adipose tissue and muscle, Km = low (5 mM), is saturated at normal glucose levels, is responsive to insulin
220
What is hexokinase?
Phosphorylates glucose to form glucose-6-phosphate, trapping glucose in the cell (inhibited by glucose-6-phosphate), IRREVERSIBLE
221
What is glucokinase?
Phosphorylates and "traps" glucose in liver and pancreatic cells, and works with GLUT2 as part of the glucose sensor in B-islet cells (induced by insulin), IRREVERSIBLE
222
What is PFK-1?
Catalyzes the rate-limiting step of glycolysis, phosphorylating fructose-6-phosphate to fructose 1,6-bisphophate using ATP (inhibited by ATP, citrate, and glucagon; activated by AMP, fructose 2,6-bisphosphate, and insulin), IRREVERSIBLE
223
What is glyceraldehyde-3-phosphate dehydrogenase?
Generates NADH while phosphorylating glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate to ADP, forming ATP and 3-phosphoglycerate (REVERSIBLE)
224
What is 3-phosphoglycerate kinase?
Performs a substrate-level phosphorylation, transferring a phosphate from 1,3-bisphosphoglycerate to ADP, forming ATP and 3-phosphoglycerate (REVERSIBLE)
225
What is pyruvate kinase?
Performs another substrate-level phosphorylation, transferring a phosphate from phosphoenolpyruvate to ADP, forming ATP and pyruvate (activated by fructose 1,6-bisphosphate), IRREVERSIBLE
226
Why must pyruvate undergo fermentation for glycolysis to continue?
Fermentation must occur to regenerate NAD+, which is in limited supply in cells. Fermentation generates no ATP or energy carriers; it merely regenerates the coenzymes needed in glycolysis
227
Why is it necessary that fetal hemoglobin does not bind 2,3-BPG?
The binding of 2,3-BPG decreases hemoglobin's affinity for oxygen. Fetal hemoglobin must be able to "steal" oxygen from maternal hemoglobin at the placental interface; therefore, it would be disadvantageous to lower its affinity for oxygen
228
Which enzyme is responsible for trapping galactose in the cell? What enzyme in galactose metabolism results in a product that can feed directly into glycolysis, linking the two pathways?
Galactose is phosphorylated by galactokinase, trapping it in the cell. Galactose-1-phosphate uridyltransferase produces glucose 1-phosphate, a glycolytic intermediate; thus linking the pathways
229
Which enzyme is responsible for trapping fructose in the cell? What enzyme in fructose metabolism results in a product that can feed directly into glycolysis, linking the two pathways?
Fructose is phosphorylated by fructokinase, trapping it in the cell (with a small contribution from hexokinase). Aldolase B produces dihydroxyacetone phosphate (DHAP) and glyceraldehyde (which can be phosphorylated to form glyceraldehyde-3-phosphate), which are glycolytic intermediates, thus linking the pathways
230
What are the reactants and products of the pyruvate dehydrogenase complex?
Reactants = Pyruvate, NAD+ and CoA, Products = Acetyl-CoA, NADH, CO2
231
How does acetyl-CoA affect PDH complex activity?
Acetyl CoA inhibits the PDH complex (pyruvate can then be used to form other products, such as oxaloacetate for use in gluconeogenesis)
232
Under what physiological conditions should the body carry out gluconeogenesis?
When an individual has been fasting for over 12 hours. To carry out gluconeogenesis, hepatic (and renal) cells must have enough energy to drive the process of glucose creation, which requires sufficient fat stores to undergo B-oxidation.
233
What are the four enzymes unique to gluconeogenesis?
Pyruvate carboxylase (replaces pyruvate kinase), phosphoenolpyruvate carboxylase (replaces pyruvate kinase), fructose-1,6-bisphosphatase (phosphofructokinse-1), and glucose-6-phosphatase (replaces glucokinase)
234
How does acetyl-CoA shift the metabolism of pyruvate?
Inhibits pyruvate dehydrogenase complex while activating pyruvate carboxylase (shift: burning pyruvate in citric acid cycle -> creating new glucose molecules for the rest of the body)
235
Given that a glycogen storage disorder affects the last enzyme of gluconeogenesis, predict the associated metabolic derangement that occurs.
Last enzyme in gluconeogenesis is glucose-6-phosphatase, so patients are unable to perform gluconeogenesis and glycogenolysis (unable to produce glucose during periods of fasting), resulting in a buildup of intermediates
236
What are three primary functions of NADPH?
Lipid biosynthesis, bactericidal bleach formation in certain white blood cells, and maintenance of glutathione stores to protect against reactive oxygen species
237
A man collapses while running a marathon and is taken to the emergency room. His blood is found to be somewhat acidic, and further tests show increased lactate dehydrogenase activity. This enzyme is involved in which of the following pathways?
Anaerobic glycolysis
238
Which of the following organs does NOT require a constant supply of glucose from the blood for energy during a fast?
Liver
239
When fatty acid B-oxidation predominates in the liver, mitochondrial pyruvate is most likely to be:
Carboxylated to oxaloacetate for entry into gluconeogenesis
240
A biopsy is done on a child with an enlarged liver and shows accumulation of glycogen granules with single glucose residues remaining at the branch points near the periphery of the granule. The most likely genetic defect is in the gene encoding:
a-1,6 glucosidase (part of debranching enzyme complex)
241
An investigator is measuring the activity of various enzymes involved in reactions of intermediary metabolism. One of the enzymes has greatly decreased activity compared to reference values. The buffer of the assay contains citrate. Which of the following enzymes would most likely be directly affected by the use of citrate?
Phosphofructokinase-1 (no citrate -> slows citric acid cycle -> negatively affect PFK)
242
A man is given antibiotics to treat a urinary tract infection and develops an episode of red blood cell lysis. Further studies show weakness of the plasma membrane and Heinz bodies (collections of oxidized hemoglobin). Which of the following enzymes is most likely defective in this patient?
Glucose-6-phosphate dehydrogenase (stress on pentose phosphate pathway)
243
After an overnight fast, which of the following processes would be expected to occur at an elevated rate compared with the well-fed state?
Glycogenolysis (would need to break down glycogen if you haven't been eating)
244
What is the overall reaction of the pyruvate dehydrogenase complex?
Pyruvate + CoA-SH + NAD+ -> acetyl-CoA + CO2 + NADH + H+
245
What other molecules can be used to make acetyl-CoA, and how does the body perform this conversion for each?
Fatty acids, ketogenic amino acids, ketones and alcohols
246
What is the purpose of all the reactions that collectively make up the citric acid cycle?
Complete oxidation of carbons in intermediates to CO2, forming energy carriers such as NADH and FADH2 for the ETC
247
What enzyme catalyzes the rate-limiting step of the citric acid cycle?
Isocitrate dehydrogenase
248
What are the three main sites of regulation within the citric acid cycle? What molecules inhibit and activate the three main check points?
Citrate synthase (inhibitors: ATP, NADH, succinyl-CoA, citrate), isocitrate dehydrogenase (inhibitors: ATP, NADH; activators: ADP, NAD+), alpha-ketogluterate complex (inhibitors: ATP, NADH, succinyl-CoA; activators: ADP, Ca2+)
249
Which complexes are associated with pumping a proton into the intermembrane space, acquiring electrons from NADH, acquiring electrons from FADH2, and having the highest reduction potential?
Pumping proton into intermembrane space = complex 1,2,4; acquiring electrons from NADH = complex 1; acquiring electrons from FADH2 = complex 2; highest reduction potential potential = complex 4
250
What role does the electron transport chain play in the generation of ATP?
Generates the proton-motive force, an electrochemical gradient across the inner mitochondrial membrane, which provides the energy for ATP synthase to function
251
Based on its needs, which of the two shuttle mechanisms is cardiac muscle most likely to utilize? Why?
Malate-aspartate shuttle (more efficient shuttle, makes sense to use it to maximize ATP yield)
252
What is the difference between the ETC and oxidative phosphorylation?
ETC = physical set of intermembrane proteins located on the inner mitochondrial matrix, and they undergo oxidation-reduction reactions as they transfer electrons to oxygen, the final electron acceptor (as electrons are transferred, a proton-motive force is generated in the intermembrane space); OXPHOS = the process by which ATP is generated via harnessing the proton gradient, and it utilizes ATP synthase to do so
253
The delta G of NADH reducing oxygen directly is significantly greater than any individual step along the electron transport chain. If this is the case, why does transferring electrons along the ETC generate more ATP than direct reduction of oxygen by NADH?
By splitting up electron transfer into several complexes, enough energy is released to facilitate the creation of a proton gradient at many locations (greater proton gradient = greater ATP generation)
254
During a myocardial infarction, the oxygen supply to an area of the heart is dramatically reduced, forcing the cardiac myocytes to switch to anaerobic metabolism. Under these conditions, which of the following enzymes would be activated by increased levels of intracellular AMP?
Phosphofructokinase-1
255
A patient has been exposed to a toxic compound that increases the permeability of mitochondrial membranes to proteins. Which of the following metabolic changes would be expected in this patient?
Increased oxygen utilization
256
Where does the citric acid cycle take place?
Mitchondrial matrix
257
Fatty acids enter the catabolic pathway in the form of:
Acetyl-CoA
258
In which part of the cell is cytochrome c located?
Inner mitochondrial membrane
259
How much ATP is produced from NADH and FADH2?
NADH = 2.5; FADH2 = 1.5
260
Why is it preferable to cleave thioester links rather than typical ester links in aerobic metabolism?
Thioester hydrolysis has a higher energy yield
261
Which of the following best explains why cytosolic NADH can yield potentially less ATP than mitchondrial NADH?
Electron transfer from cytosol to matrix can take more than one pathway
262
Which complex does NOT contribute to the proton-motive force?
Complex 2
263
What is the most likely reason the body stores the bulk of its calories in the form of triglycerides and not glycogen?
Glycogen storage requires a significant amount of water (polar, hydrophilic) while triglyceride storage does not (nonpolar, hydrophobic)
264
Why is the activity of lactate dehydrogenase necessary for long-term glycolysis under anaerobic conditions?
Cells have a limited pool of NAD+ that must be replenished for glycolysis to continue indefinitely
265
In a fasting state:
Cells use beta-oxidation of fatty acids for energy, yields acetyl-CoA which is used to form ketone bodies via ketogenesis
266
What helps maintain flexibility in cell membranes through interactions with the phospholipid fatty acid chains?
Cholesterol
267
When a cell is at Nernst equilibrium for a specific ion, this means that:
The force due to electric potential is balanced by the force due to the concentration gradient of that ion
268
Where is glucose normally absorbed in the kidney?
Proximal convoluted tubule
269
What does acetylcholine stimulate?
Sweat glands, attention, arousal (not sympathetic NS)
270
What is chemiosmosis?
The hydrogen ions passing through the special channels in ATP synthase and causing it to turn, forming ATP
271
What is oxidative phosphorylation?
Phosphorylation = ADP + P -> ATP, oxidative = phosphorylation is happening because of oxidation of all of these enzymes, including NADH
272
What does carbonic anhydrase do?
Assists rapid inter-conversion of carbon dioxide and water into carbonic acid, protons and bicarbonate ions
273
In what environment does a disulfide bridge occur?
An oxidizing environment
274
How does temperature, pH, chemicals, and enzymes affect protein structure?
Temperature denatures 2", 3", 4" structure; pH denatures 3", 4"; chemicals denatures 2", 3", 4"; enzymes denatures 1"
275
What is the difference between agarose gel and SDS gel electrophoresis?
SDS = small molecules; agarose = big molecules
276
What is the equation for catalytic efficiency?
kcat/Km
277
What is the impact of a competitive inhibitor?
Bind to active site (Increase Km, no change in Vmax)
278
What is the impact of a noncompetitive inhibitor?
Bind to allosteric site (unchanged Km, decreased Vmax)
279
What is the impact of an uncompetitive inhibitor?
Bind to E-S complex (decrease Km, decrease Vmax)
280
What is the difference between denaturation and hybridization?
Denaturation = splitting apart the two strands of DNA; hybridization = putting 2 strands of DNA together
281
What does topoisomerase do?
Prevent supercoiling (uncoils)
282
How to remember DNA polymerase I vs DNA polymerase III?
DNA poly I = removes RNA primer; DNA poly III = can draw an x in the middle of the III (EXOnuclease activity, proofreads and replicates)
283
What does degenerate mean?
Many codons code for the same AA
284
What does snRNPs and snRNAs form?
The spliceosome, completes transesterification reaction to remove introns and ligate exons
285
What are some non-coding RNAs?
miRNA (gene silencing), rRNA, tRNA, snoRNA, snRNA
286
What is the difference between a point mutation and a missense mutation?
Point mutation = 1 AA replaced with another; missense mutation = any mutation that changes 1 AA to another
287
What is senescence?
Dormant state where DNA does not divide anymore
288
What are some post-transcriptional modifications?
5' cap (protects from exonucleases); 3'-poly A tail (protects, promotes, regulates)
289
What are nucleosomes?
Histones and DNA
290
What is the hybridization technique?
Lyse cells, expose contents to well with fluorescent tag -> certain color -> gene expression up or down-regulated
291
What are telomeres?
Ends of chromosomes, prevent them from deterioration (buffer zone = contain no important genes), prevent the chromosomes from sticking to each other (highly repetitive)
292
What type of DNA is present in important genetic info?
Single copy (exons)
293
What is DNA cloning?
Bacteria, plasmid + heat shock -> some bacteria will uptake the plasmid
294
Where do crossovers occur in meiosis?
Prophase I, occurs at chiasma, causes variation
295
What is the synaptonemal complex?
A protein structure that forms between homologous chromosomes during meiosis, mediates synapsis and recombination during meiosis I
296
What is genetic drift?
Random changes in reproduction of the population (more likely with small populations)
297
What is a polymorphism?
Different forms of alleles/traits
298
What is the founder effect?
Organisms go and live in a new place, decrease in population
299
What is a bottleneck?
Disaster -> massive reduction in population -> big example of genetic drift
300
What is allopatric vs. sympatric speciation?
Allopatric = geographic speciation; sympatric = reproductive isolation within the population
301
Why is the pentose phosphate pathway called the pentose phosphate pathway?
Pentose = 5-carbon sugar; phosphate = phosphorylated molecule -> NADPH (no ATP formed/used, uses glucose-6-phosphate)
302
How are fats digested, mobilized, and transported?
Lipases in small intestine breaks down fats -> FAs broken down in TAGs -> lipoproteins package hydrophobic moleculess into the core of a protein molecule (chylomicrons produced) -> lipoprotein lipase breaks down into free FAs and glycerol (stimulated by insulin), adipose cells store fat (hormone sensitive lipase break down FAs), everything except fats pass through liver, proteins/carbohydrates go into capillaries, fats go into lacteals (much larger pores) -> ducts -> veins -> drained in thoracic vein
303
What are gap junctions?
Tunnel, let water/ions flow through (cardiac muscle)
304
What are tight junctions?
Water tight seal (bladder, kidney, intestine)
305
What are desmosomes?
Spot welds (skin, intestines)
306
What is the nucleolus?
Inside the nucleus, made up of proteins and ribonucleic acids, function = transcribe rRNA
307
What is the nuclear envelope/nuclear pores?
Nuclear envelope = a double membrane system (inner and outer membrane); nuclear pores = holes in nuclear envelope where things can pass in and out of the nucleus
308
What are lysosomes?
Digest various molecules and substances (autophagy = "self eating"), crinophagy = digest excess secretory produt
309
What is the smooth ER?
Synthesizes lipids, metabolizes carbs, detox drugs/other toxins
310
What is the rough ER?
Site of protein synthesis, post-translational modifications
311
What is the Golgi apparatus?
Modifies proteins that are made in the RER, sorts/sends proteins to proper destination, synthesis of macromolecules for secretion
312
What are intermediate filaments?
Intermediate = between layers = structural support (resist mechanical stress), comparable to strings of a mattress
313
What are microtubules?
Alpha-tubulin and beta-tubulin form a dimer, minus end anchored to MTOC (centrosome = 9 triplets of microtubules; cilia and flagella = 9 + 2 rule), form network from soma to synaptic terminal
314
What are cilia and flagella?
Cilia = hair-like coverings, push mucus into respiratory tract; flagella = tail-like projections, help cells move (dynein help cilia and flagella move)
315
What is the permeability of the inner and outer membrane of the mitochondria?
Outer membrane = lipid bilayer = permeable to small molecules; inner membrane = not permeable, have cristae to increase SA for cellular respiration
316
What are viroids?
Circular DNA (found in plants, catalytic RNA => self-cleave to create more viroids) - SMALL INFECTIOUS PATHOGENS
317
What are prions?
Infectious proteins; changes alpha helices to beta sheets
318
What is the difference between enveloped and non-enveloped virus?
Enveloped = directly fuses with the membrane ; non-enveloped = trick receptor into letting them in
319
How does viral replication occur?
1) Get inside cell, 2) Takes over cell's machinery and self-assemble (lytic cycle), 3) combine with host's genetic information with there are not many hosts (lysogenic cycle)
320
What is chemotaxis?
Sensing chemicals and moving towards/away from it
321
What is the process of spermatogenesis?
Spermatogonium -> primary spermatocyte -> 2 secondary spermatocytes -> 2 spermatids for each secondary spermatocyte -> spermatozoa
322
What makes sperm/testosterone?
Seminiferous tubules make sperm (Sertoli cells nourish the sperm); cells of Leydig make testosterone
323
What is fertilization?
Sperm fertilizing egg, then called a zygote
324
What is cleavage?
Splitting without growth (in zona pellucida)
325
Describe after cleavage to gastrulation.
After cleavage, forms a morula -> differentiation (trophoblasts and embryoblasts) -> inner cell mass and blastocoel (blastocyst) -> lose zone pellucida and gain amniotic cavity -> form epiblasts/hypoblasts, bilaminar disk, primitive streak -> gastrulation
326
What is gastrulation?
Forming primary germ layers (mesoderm forms notochord, induces a change in ectoderm -> neural plate becomes neural tube, neural crest cells form, give rise to ectoderm)
327
What part of the antibody recognizes the antigen?
The variable region of the heavy and light chains
328
MHC I molecules display antigens derived from which type of pathogen?
Viruses (MHC II = bacteria)
329
A patient requiring a blood transfusion is discovered to have type AB- negative blood. Which donor blood types can they accept?
B-, A-, AB-, and O-
330
Which immunoglobulin can cross the placenta?
IgG
331
Which immunoglobulin is involved in the allergy response?
IgE
332
There are two types of alvelolar cells that line the alveolar sacs in the lungs. Type I cells participate in gas exchange. What do type II cells do?
They secrete surfactant, a chemical that helps the alveoli stay open
333
What are the directions of vesicle traffic in the cell?
ER -> Golgi, Golgi -> ER
334
How are mitochondria semi-autonomous?
They contain some of their own genes and replicate independently of the nucleus via binary fission
335
Where is the electron transport chain located in prokaryotic cells?
Plasma membrane
336
A virologist wants to determine if the position of a penicillin resistance gene is close to the origin of replication of her plasmid. She initiates conjugation with bacteria that contain the plasmid with recipient bacteria. What can she do to determine the gene's location?
Disrupt the conjugation at different times. Then, determine the proportion of penicillin resistant bacteria in the coculture.
337
The formation of prions can be described as a malfunctioning of what process?
Post-translational modification
338
During early development, an embryo contains an accessible genome and expresses many of the proteins coded for in the genome. Which organelle most likely contributes to this activity?
Nucleolus (synthesizes rRNA)
339
The synthesis of progesterone most directly relies upon which organelle?
Smooth ER
340
Which of the following domains of life utilizes histones to wrap DNA and is noted for its unique ability to utilize alternative sources of energy such as sulfur and ammonia?
Archaea
341
Based on structure and genome, which of the following most closely resembles mitochondria?
Gram-negative bacteria
342
A virologist wants to modify her virus so that it can infect more cell types. Which of the following viral genes should she change?
Tail fibers
343
What are meissner corpuscles?
Rapidly-adapting, encapsulated neurons that responds to low-frequency vibrations and fine touch; they are located in the glabrous skin on fingertips and eyelids
344
What are pacinian corpuscles?
Rapidly-adapting, deep receptors that respond to deep pressure and high-frequency vibration
345
What are merkel cells?
Slow-adapting, unencapsulated nerve endings that respond to light touch; they are present in the upper layers of skin that has hair or is glabrous
346
What are ruffini endings?
Slow adapting, encapsulated receptors that respond to skin stretch and are present in both the glabrous and hairy skin
347
When you exercise, what is the result on the hemoglobin-oxygen curve?
Decreased pH, increased temperature, increased BP-2,3G, increased amount of carbon dioxide (decreased affinity of Hb to O2)
348
Catecholamines are:
Hormones and neurotransmitters
349
The stereochemical designations alpha and beta distinguish between:
Epimers at an anomeric carbon atom
350
Which event is directly mediated by a ligand-gated ion channel?
Influx of Na+ across the motor end plate resulting in the depolarization of the muscle fiber membrane (when Na+ ion channels bind the ligand acetylcholine)
351
What happens in a Southern blot?
Uses a restriction digest to differentiate between mutant and wild-type alleles (mutation should create or eliminate a restriction site, most of which are palindromic sequences of 4-6 base pairs
352
What is the average molecular weight of an amino acid?
110 Da
353
If an enzyme has a Hill coefficient that is ~ 1, what does that mean?
Negative cooperativity
354
For isoelectric focusing to work:
A stable pH gradient must be established in the gel
355
Kd is:
Dissociation constant (higher affinity = lower Kd)
356
What are signal sequence domains?
Protein domains required for proteins that are directed toward secretory pathways
357
What element differs between different cells in an organism?
Nuclear factors (a type of transcription factors)
358
How many molecules of reduced electron carrier are generated during conversion of α-ketoglutarate to oxaloacetate in the citric acid cycle?
Three (2 NADH and 1 FADH2) - NADH is made during alpha-ketogluterate dehydrogenase, isocitrate dehydrogenase, and malate dehydrogenase; FADH2 is made during fumarase
359
RNA polymerase is not used in:
cDNA cloning
360
When glucagon binds to its receptor:
It activates its coupled G protein, activities of the adenylate cyclase, protein kinase A and cAMP are increased
361
Infusion of glucagon will result in:
Mobilization of endogenous glucose storage thereby preventing hypoglycemia and brain injury
362
In the pentose phosphate way, which enzyme catalyzes the production of 6-phosphogluconolactone?
Glucose 6-phosphate dehydrogenase
363
For a respiratory quotient:
0.7 = lipids, 0.8-0.9 = amino acids, 1 = carbohydrates
364
What is convergent evolution and divergent evolution?
Convergent evolution = different lineage, evolving closer together to be similar (ex. dolphin and shark); divergent evolution = same lineage, evolving apart to be more different (ex. bats and horses)
365
Beta-OHB is a component of:
Ketone bodies
366
The adrenal medulla is part of which branches of the peripheral nervous system?
The sympathetic branch of the autonomic nervous system only
367
Why are tubulin levels measured in a Western Blot?
Tubulin is used as a control to assess the total protein level in different samples
368
What does CoQ 10 do in the electron transport chain?
It brings electrons from Complex II to Complex III
369
Certain viruses contain RNA as their genetic material. One of the ways these RNA viruses replicate themselves is to:
Code for or carry a transcriptase that copies viral RNA
370
Based on the passage, which of the following conditions most likely contributed to the boy’s weight loss?
A decrease in the surface area of the small intestine, leading to a decrease in nutrient absorption
371
Within the intestines, unabsorbed fats are broken down into fatty acids by intestinal bacteria. Given this, excess unabsorbed fats most likely have which of the following effects within the intestines?
They increase the osmotic pressure within the intestines, leading to diarrhea
372
The normal path of sperm movement from the male testis to the point of fertilization in the female is:
Epididymis, vas deferens, urethra, vagina, cervix, uterus, fallopian tube
373
Albumin is the major blood osmoregulatory protein. The most likely effect of a sharp rise in the level of serum albumin is:
An influx of interstitial fluid into the bloodstream
374
If chromosomal duplication before tetrad formation occurred twice during spermatogenesis, while the other steps of meiosis proceeded normally, which of the following would result from a single spermatocyte?
Four diploid sperm
375
In the human "knee-jerk" reflex, the knee is struck and the lower leg jerks forward. Which of the following represents the complete pathway that the nerve impulse travels in effecting this response?
Sensory neuron, motor neuron (simple monosynaptic stretch reflex)
376
Synthesis of antibody proteins in eukaryotic cells is associated with what organelle?
ER (Rough ER)
377
Rates of endocytosis vary from cell type to cell type. What cell would be predicted to have the highest rate of endocytosis?
Macrophage
378
What comprises the mineral component of human bone?
Hydroxyapatite (Ca10[PO4]6[OH]2)
379
How many molecules of NADH are produced from six molecules of glucose that undergo glycolysis?
12
380
Which combination of lipid type and temperature results in the most disordered membrane?
Lipids with unsaturated acyl chains at high temperature
381
Which event occurs when a G protein-coupled receptor is activated?
The α subunit binds GTP
382
What does caspase activation do?
Leads to apoptosis
383
Between lysine and arginine, which one is more basic?
Arginine
384
Specific activity is a measure of:
The enzyme units per milligram of total protein in a solution
385
Researchers noted that in the absence of a reducing agent the elution time of a certain protein from a size-exclusion column decreased considerably relative to the elution time when the buffer contained a reducing agent. Which type of molecular interaction was responsible for this observation?
Disulfide bonding
386
The transition of which amino acid from the interior of a soluble globular protein to the surface is associated with the largest positive ΔGº?
Phenylalanine
387
Disruption of two disulfide bonds within a protein requires:
2 molecules of NADH
388
Cyanogen bromide cleaves peptide bonds by first undergoing nucleophilic attack by the side chain of a methionine residue. Which atom is the nucleophile in this reaction?
Sulfur
389
What are some functions of binding proteins?
Regulation of gene transcription, sequestration of solutes, transport of substances that are insoluble in water
390
In the menstruation cycle of a healthy adult female as:
Estogen levels rise, the endometrium thickness increases
391
A woman takes a pregnancy test measuring human chorionic gonadotropin (hCG) levels. The test result comes back negative. However, she is in her sixteenth week of pregnancy. Which of the following explains the false-negative result?
By the second trimester, the placenta secretes high amounts of estrogen and progesterone
392
Which of the following inherited disorders can result from malfunctioning microtubules?
Down's Syndrome
393
What role does estrogen play in the menstrual cycle?
Regrowth and vascularization of the endometrial lining
394
What is true about ovulation?
It is preceded by a rise in estrogen during the follicular phase, which is characterized by regrowth of the endometrium
395
In a healthy female, the corpus luteum:
Is functionally replaced by the placenta after the first trimester
396
When is the first meiotic division of oogenesis completed, forming the secondary oocyte?
Shortly before ovulation
397
At the end of his initial hospital stay, a few E. coli cells remained in the patient’s colon, even though he was taking antibiotics. These cells were most likely present because:
Chance mutations in a few E. coli before the treatment made these cells and their descendants antibiotic-resistant
398
The patient’s ruptured appendix required treatment with antibiotics because he had a bacterial infection caused by:
E. coli entering the abdominal cavity from the appendix
399
Assuming that the vertebrates were all of comparable size, which of the following vertebrates would be expected to have the strongest and heaviest bones?
A land-dwelling mammal
400
In eukaryotes, oxidative phosphorylation occurs in the mitochondrion. The analogous structure used by bacteria to carry out oxidative phosphorylation is the:
Plasma membrane
401
What are some of the processes controlled by the sympathetic nervous system?
Peristalsis, secretion of digestive enzymes, nutrient delivery to muscles and organs
402
The amount of NE released by sympathetic nerve terminals will be most strongly influenced by a change in which of the following?
Extracellular Ca2+
403
The osmotic concentration of plasma proteins in the venous side of capillaries helps reduce the amount of interstitial fluid in tissues by inducing:
Passive H2O diffusion along a concentration gradient
404
Capillaries in the kidney and elsewhere in the body maintain fluid homeostasis by balancing hydrostatic and osmotic pressures. Which of the following is the initial effect of a blood clot forming on the venous side of a capillary bed?
Net fluid flow in the direction of interstitial spaces will increase
405
Radioactively labeled uracil is added to a culture of actively dividing mammalian cells. In which of the following cell structures will the uracil be incorporated?
Ribosomes
406
What occurs during normal inspiration of air in mammals?
Elevation of rib cage, contraction of diaphragm, reduction of pressure in the pleural cavity, contration of external intercostal muscles
407
The parasympathetic nerves to the iris release acetylcholine onto the circular muscles causing:
Pupillary constriction
408
Rapid removal of acetylcholine from the circualtion would inactivate parasympathetic:
Stimulation of digestive secretion consonant with rapid arousal of the animal in an emergency
409
The autonomic nerve fibers that directly innervate the heart to cause cardiac slowing are:
Parasympathetic motor fibers
410
In terms of size, viruses are:
Smaller than all known eukaryotic cells
411
What type of media should be used to grow virions in the laboratory?
A tissue culture (viruses need intact host-cells, aka NOT non-cellular media)
412
A microbe pathogen was hypothesized as the causative agent of the disease described in the passage because:
The disease was infectious
413
Hybridization requires:
Base pairing between complementary nucleic acid sequences
414
In human females, mitotic divisions of oogonia that lead to formation of presumptive egg cells (primary oocytes) occur between:
Fertilization and birth only
415
Which tissues have cells that are in direct contact with the external environment or elements of the external environment?
The lining of the reproductive tract, respiratory tract, and gastrointestinal tract
416
Between the heart, arteries, arterioles, and capillaries, which one would have the lowest pressure?
Capillaries
417
What is the equation for blood flow?
Pressure = cardiac output x vascular resistance
418
Enhanced activity of which muscles would cause vasoconstriction?
Smooth muscle (leads to hypertension)
419
What is a primary process of the colon?
Water absorption
420
An ulcer that penetrated the wall of the intestine would allow the contents of the gastrointestinal tract to enter:
The peritoneal cavity
421
What is the pleural cavity?
The space that lies between the pleura, the two thin membrane that line and surround the lungs
422
What is the perineum?
The area between the anus and the scrotum or vulva
423
The finches observed by Darwin on the Galapagos Islands are an example of adaptive radiation. In order to set up conditions that would produce adaptive radiation, it would be necessary to place members of:
One species in several different environments (adaptive radiation = the divergence of one species into multiple species over time)
424
Postmenopausal women receiving estrogen and progesterone therapy will most likely experience which of the following side effects?
Periodic menstruation will resume
425
The cell type in the male reproductive system that is most analogous to the female ovum is the:
Spermatozoon
426
What correctly describes the distinction between the exocrine and endocrine portions of the testis?
The exocrine portion releases its products into ducts; the endocrine portion releases its products into the blood
427
A drug that binds to tubulin molecules of plant cells and prevents the cells from assembling spindle microtubules would most likely cause the resulting plants or plant cells to have:
More than 2 sets of chromosomes
428
Where does transcription occur in prokaryotic cells?
Cytoplasm
429
Cancer cells most likely have an abnormality in their:
DNA
430
Fever in septic shock leads to which of the following compensation mechanisms?
Dilation of capillary beds in the skin
431
Pulmonary arterial blood differs from the aortic blood because it has:
Less O2, more CO2, and lower pH
432
In comparison with the wall of the right ventricle of the heart, the left ventricular wall is:
Thicker and generates a higher pressure when it contracts (right = lungs; left = rest of body)
433
If an artery that supplies blood to a lung lobe was blocked but ventilation to the lobe was unaffected, how would alveolar gas partial pressures change?
PO2 would increase and PCO2 would decrease
434
A characteristic common to arteries, veins, and capillaries is the:
Presence of a layer of endothelial cells
435
The pancreas produces which of the following substances for the digestive system?
Proteolytic enzymes
436
Enzymes do not affect:
Keq values
437
Transferrins are an important class of mammalian glycoproteins that transport iron from the blood into appropriate cells. Once an iron-transferrin complex forms, it is recognized by a receptor and endocytosed into a gradually-acidified endosome. Which of the following most likely represents the affinity of a transferrin for its iron ligand?
High at extracellular pH, but decreasing as pH decreases
438
When a signal molecule arrives at a G protein coupled receptor, the G protein:
Becomes activated
439
What would bind to a ligand-gated ion channel?
Serotonin, GABA, Glycine
440
Most cytochrome P450 enzymes alter the activity of drugs by:
Oxidizing them
441
A defining characteristic of proteins that act as transcription factors (such as STAT5b) is that they:
Contain a DNA binding domain
442
As blood passes through actively contracting skeletal muscle tissue, the affinity of hemoglobin for oxygen in the muscle tissue:
Decreases as a result of a decrease in plasma pH
443
What is Henry's law?
Relates the solubility of a gas to the pressure of the gas above the solution
444
If a question is talking about transcriptional regulation:
It is probably measuring mRNA levels (good to use RT-PCR)
445
A peptide consisting of nine amino acids was partially hydrolysed. Three different tripeptides were isolated. None of the tripeptides share a common amino acid. Based on the data, what is the total number of possible structures possible for the full-length peptide?
6
446
What describes the inactive X chromosome in mammalian females?
It is one of the last chromosomes to replicate
447
When more bile is released:
The muscle in the wall of the gallbladder contracts and the hepatopancreatic sphincter relaxes
448
On the day of the experiment, the subjects drank about 1 L of water on average and excreted about 400 mL of urine. The most likely explanation for the difference between water intake and urine excretion is that:
Water was excreted via the skin and the lungs
449
The osmolarity of urine in these subjects was 958 milliosmoles/L, compared with an average blood osmolarity of 284 milliosmoles/L. The higher osmolarity of urine suggests that:
The kidneys are acting to conserve water
450
Which of the following responses could maintain cardiac output under dehydration conditions that reduce blood volume?
An increase in heart rate
451
During exercise, the osmolarity of venous blood from active muscles will increase as a result of an increase in:
Lactate concentration in plasma.
452
Which pathway depicts the sequence of cellular compartments traversed by newly synthesized GABA-receptor subunits as they move to the cell surface?
Rough endoplasmic reticulum, Golgi complex, and secretory transport vesicle
453
Which process is most likely responsible for the failure of a gamete to receive a copy of a particular chromosome?
Non-disjunction
454
How might the expression of telomerase in embryonic stem cells allow them to create more daughter cells in their lifetime?
The telomerase prevents crucial biosynthesis genes located near the telomere from being silenced
455
A chemist makes a drug that should lead to rapid, direct degradation of its target protein. However, when the chemist performs a Western blot for the protein after treating cells with the drug, she only notices a small decrease in the amount of protein. Which of the following could explain the partial decrease?
The drug targets a region of the protein made by an exon that is alternatively spliced
456
What is a difference between DNA and RNA?
RNA is more reactive than DNA
457
Growth hormone:
Stimulates insulin-like growth factor 1 (IGF-1)
458
In prokaryotic translation:
Initiation is facilitated by a Shine-Dalgarno sequence in the mRNA
459
If the p value is less than 0.05:
One should reject the null hypothesis
460
What is the normal fate of a tRNA molecule after delivering its amino acid to a ribosome?
The tRNA is recharged with a new amino acid by an aminoacyl-tRNA synthetase.
461
What is a case-control study?
Subjects with a certain outcome are assessed for previous risk factors.
462
A biologist suspects that she has found a new oncogene involved with melanoma growth. Which of the following results suggests that the oncogene is activated through an epigenetic mechanism?
The sequence of the exons of the oncogene in a cancer tissue sample perfectly matches the reference genome. A Western blot of the protein in a cancer sample yields a band that is thicker than the band seen in a healthy control sample
463
Which of the following molecules is a direct product of beta-oxidation?
NADH (also FADH2 is)
464
In times of glucose deprivation, the body can obtain energy by utilizing its stores of fat. This involves the production of ketone bodies, the metabolism of which is relatively inefficient. One particular ketone body can be detected by smelling one’s breath. Which product is responsible for yielding sweet-smelling breath and sweat?
Acetone
465
A pharmaceutical compound targets and inhibits the carnitine shuttles used by cells. A human cell treated with this medication currently displays excess acetyl-CoA inside the mitochondria and insufficient cytosolic acetyl-CoA. What will be the most direct result of this circumstance?
Fatty acid synthesis (occurs in the cytosol)
466
Urea is excreted as an end product of amino acid metabolism. From which molecule is urea derived, and how is that substance freed from amino acid residues?
Ammonia; it is generated when amino groups are removed via an aminotransferase.
467
What is a nucleoside?
A five-carbon sugar attached to a nitrogenous base
468
Thyroxine is a hormone produced by the thyroid in a reaction that uses a tyrosine substrate. This hormone affects virtually every cell in the body by binding to its cytosolic receptor and translocating into the nucleus. Compared to steroid hormones, thyroxine:
Differs in its tissue of origin, but shares a similar mechanism of action
469
Proper eukaryotic DNA replication requires a number of enzymes. The elongation step of replication involves:
DNA polymerase
470
Four distinct mRNA codons correspond to the amino acid valine. However, only a single tRNA molecule is able to add valine residues to a growing peptide chain. How is it possible that one anticodon can recognize multiple codons?
Anticodons can experience non-Watson-and-Crick base interactions known as wobble base pairings
471
One advantage of the degeneracy of the genetic code is that:
It reduces the effect of point mutations because multiple codons may correspond to the same amino acid
472
Which type of RNA is most active during post-transcriptional processing?
snRNA
473
What does the poly-A tail do?
Prevents enzymatic degradation of the transcript
474
Which of the following enzymes, structures, or processes is NOT required to produce a mature mRNA transcript?
A stop codon
475
A certain protein release factor functions to specifically recognize stop codons and terminate translation. How many tRNA molecules bind to the same codons as this factor?
None
476
What is the difference between connexin, cadherins, occludin, and fibronectin?
Fibronectin = bridging protein; connexin = gap junction protein; cadherins = cell-cell junctions; occludin = tight cell-cell juntions
477
What are some examples of exocrine glands?
Liver, pancreas, salivary gland
478
Injuries to cartilaginous tissue, such as torn and stretched ligaments, can often take quite some time to heal. Which statement best explains why injuries to this type of connective tissue heal so slowly?
Cartilage relies on diffusive rather than direct vascular delivery of nutrients, and repairing cells therefore have a hard time sustaining increased activity
479
A congenital defect in the synthesis of the proteins cloudin and occludin is most likely to impact the function of the:
Intestinal lining
480
The parasympathetic nervous system promotes vasodilation in which of the following areas?
Small intestine and stomach
481
Which of the following neurons is most likely to fire an action potential?
An unmyelinated neuron that receives multiple EPSPs that summate temporally
482
If the anterior pituitary were suddenly rendered incapable of producing hormones, which of the following compounds would be directly affected?
GH and LH
483
A newly discovered biological factor is found to bind to a cytosolic nuclear receptor after entering the cell. Based on this observation, this molecule is likely which type of hormone?
Steroid hormone
484
What organ synthesizes steroid hormones?
Adrenal cortex
485
Oncotic pressure is mainly generated by serum albumin. How can this molecule best be described?
As a soluble 65-kd protein that serves to draw fluid into the venous ends of capillary beds
486
In fluid dynamics, the continuity equation relates the cross-sectional area of a vessel to the speed of fluid moving through it. According to this equation:
Blood travels slower in capillaries than in arterioles
487
Increased blood viscosity is a known contributor to the development of chronic hypertension. Which of the following is likely to increase blood viscosity?
Sickle-cell anemia
488
Carbonic anhydrase catalyzes the conversion of water and carbon dioxide to carbonic acid. This process is a crucial part of the maintenance of a buffered blood pH. Which metal cofactor is necessary for carbonic anhydrase to function?
Zinc
489
HIV infects and kills helper T cells. Which of the following cell types will function less effectively in a patient in the late stages of AIDS?
Macrophages, B cells, and cytotoxic T cells
490
Some bacterial toxins are able to bind with high affinity to MHC, displacing whatever peptide was previously bound. As a result, the immune response is systemically activated without a clear target. The resulting pathology would most resemble:
Anaphylaxis
491
How does mitotic prophase differ from prophase II of meiosis?
In prophase II, half of the number of chromosomes are present in comparison to prophase
492
A low recombination frequency means:
The two genes being measured are physically close
493
What might be a consequence of a dysfunctional synaptonemal complex?
During meiosis, problems might occur with recombination and synapsis
494
What is sympatric speciation vs. allopatric speciation vs. parapatric speciation?
Allopatric = physical barrier; sympatric = no physical barrier; parapatric = two distinct populations overlap
495
Which steps involved in the contraction of a skeletal muscle require binding and/or hydrolysis of ATP?
Dissociation of myosin head from actin filament, conformational change that moves actin and myosin filaments relative to one another, and reuptake of calcium into the sarcoplasm
496
Platelets, endothelial cells, and mature RBCs are all:
Bone-marrow derived
497
Lysine and amino acids with similar chemical characteristics in histones most likely promote the interaction of histones with which DNA components?
Phosphate groups
498
The liver synthesizes factors that act cooperatively with platelets to facilitate which physiological process?
Blood clotting
499
The amino acid precursor of serotonin is best described as having which type of R group?
Aromatic (tryptophan)
500
Increasing the volume of air that reaches the alveoli and takes part in gas exchange will cause blood pH to:
Increase, because the partial pressure of CO2 in the blood will decrease
501
What is the difference between cofactors, coenzymes, and vitamins?
Cofactors = catalysts; coenzymes = organic, carbon-based; carrier molecules (ex. NADH); vitamins = organic cofactors/coenzymes (ex. Mg2+, Ca)
502
What is senescence?
A dormant state where DNA does not divide anymore
503
What is the difference between DNA polymerase I and DNA polymerase III?
1: removes RNA primer @ end of replication; 3: replicates, proofreads (exonuclease activity)
504
What is the difference between single copy, repetitive, and highly repetitive?
Single copy = most of organism's important genetic info, low mutation rate; repetitive = found near centromere, higher mutation rate; highly repetitive = no genes, not transcribed/translated, ex. telomeres
505
What is a synaptonemal complex?
A protein structure that forms between homologous chromosomes uring meiosis, mediates synapsis and recombination during meiosis I
506
What does glycogen synthase do?
Takes UDP off and attaches glucose to glycogen, allows glycogenesis to occur
507
What does glycogen phosphorylase do?
Adds UDP, can become G1P -> G6P -> glycolysis
508
What are microfilaments?
Can shorten and lengthen very quickly -> lengthen = polymerization; shorten = depolymerization; gross movement of cell
509
What are microtubules?
In centrosome (9 triplets) and cilia/flagella (9+2), dynein help cilia and flagella move (- end is anchored to MTOC)
510
What is the secretory pathway?
ER -> Golgi -> Lysosome
511
What are some functions of smooth/rough ER?
Smooth = synthesize lipids, metabolize carbs, detox of drugs; rough = protein synthesis, post-translational modifications
512
What are viroids vs. prions?
Viroids = circular DNA, self-cleaves to create more viroids; prions = changes alpha helices to beta sheets
513
What is the order of sperm development?
Spermatogonium -> primary spermatocyte -> 2 secondary spermatocyte -> 2 spermatids per spermatocyte -> spermatoza -> epididymis
514
What are the stages of early development?
Zygote -> cleavage -> morula -> trophoblasts + embryoblasts -> blastocoel -> amniotic cavity -> epiblasts/hypoblasts -> bilaminar disk -> primitive sterak -> gastrulation -> trilaminar disk -> neurulation -> mesoderm forms notochord -> chaange in ectoderm -> neural plate becomes neural tube -> neural crest cells form
515
What is saltatory conduction?
AP jumps from node to node
516
What are GPCRs?
7 transmembrane domains, only in eukaryotes, G-proteins = proteins that can bind to GTP + GDP (ex. enzymes that produce 2nd messengers)
517
What are ligand-gated ion channels?
Found in neurons, transmembrane ion channels that open/close in response to binding of a ligand
518
What is the pathway of gas exchange in the respiratory system?
O2 -> layer of fluid -> epithelial fluid -> basement membrane -> connective tissue -> basement membrane -> endothelial cells -> capillary -> RBCs
519
What do astrocytes do?
Form BBB, structural support, glial scar, monitoring interstitial fluid, clear synapses (the "C" in astrocytes stands for CNS)
520
What do microglia do?
Inflammatory response (reactive oxygen species), phagocytosis, antigen presentation
521
What is the blood flow in the heart?
Superior vena cava -> right atrium -> tricuspid valve -> right ventricle -> pulmonory valve -> LUNGS -> left atrium -> mitral/bicuspid valve -> left ventricle -> aortic valve -> HEART
522
What is the difference between arteries and veins?
Arteries = away from heart, high pressure, low volume; veins = towards heart, low pressure, high volume
523
What is the epiglottis?
Flap of cartilage that closes off airway when you are sweating
524
What are some functions of the pancreas?
Production of enzymes (amylase, protease, lipase, ribonuclease, HCO3-)
525
What are some functions of the small intestine?
Absorption of food molecules and water, villi (active transport and facilitated diffusion), structure = duodenum, jejunum, ileum
526
What are some functions of the large intestine?
Absorption of water, bacterial flora (produce vitamin K)
527
What is the point of fatty acid oxidation?
IN MITOCHONDRIA: yield more acetyl-CoA (inhibited by insulin, enhanced by glucagon), rate limiting = carnitine acyltransferase; 4 steps = oxidation (FADH2 product), hydration, oxidation (NADH product), split off an acetyl-CoA
528
What is the point of fatty acid synthesis?
IN CYTOSOL; Citrate -> acetyl CoA+OAA -> acetyl CoA becomes malonyl via acetyl CoA carboxylase -> malonyl CoA x 2 via enzyme FA synthase -> high insulin triggers fatty acid synthesis -> fatty acid + glycerol = triglycerides (stored in adipocyte cells)
529
What is the point of the urea cycle?
Amino acid metabolism: ammonia (toxic, cannot be excreted properly); urea = non-toxic, easily excreted, process of converting ammonia -> urea (occurs in cytoplasm and mitochondria)
