Biochemistry Flashcards
(203 cards)
1
Q
Water forms Hydrogen Bonds with?
A
Sulfur, oxygen and nitrogen atom (SON)
2
Q
Define amphoteric and amphipathic
A
Amphoteric - acts as both an acid and a base, Amphipathic - has hydrophilic an hydrophobic parts
3
Q
What is the normal pH?
A
7.35 - 7.45
4
Q
DKA Criteria
A
Diabetic, Ketosis (+) urine ketones, ABG that documents acidosis
5
Q
Important physiologic buffers
A
Bicarbonate - extracellular, Proteins - intracellular
6
Q
Distinct versions of a given enzyme that catalyze the same reactions
A
Isozymes
7
Q
Enzymes that catalyze the joining together of 2 molecules coupled to the hydrolysis of ATP
A
Ligases
8
Q
Refers to the enzyme and its co-factor
A
Holoenzyme
9
Q
True or false: enzymes that follow the Michaelis-Menten equation have a hyperbolic curve
A
True - equation describes how reaction velocity varies with substrate concentration
10
Q
Reversal of competitive and non competitive inhibitors
A
Competitive - increase substrate, Noncompetitive - increase enzyme
11
Q
Vmax change during inhibition
A
Competitive - not changed, Non competitive- lowered
12
Q
What enzyme markers would best confirm a re-infarct?
A
CK-MB
13
Q
Can be used to predict whether a reaction is spontaneous or not
A
Change in free energy G - must be highly negative to favor a reaction
14
Q
Equation of Change in Free Energy
A
G = H - S
15
Q
Energy currency of the cell. It’s hydrolysis yields a large G
A
ATP, G= -7300cal/mol
16
Q
Differentiate oxygen phosphorylation from substrate level phosphorylation
A
Oxidative phosphorylation - mitochondria, oxygen needed. Substrate level phosphorylation - cytoplasm and mitochondria, oxygen not needed
17
Q
Where does the ETC occur?
A
Inner mitochondrial membrane
18
Q
2 electron carriers in the ETC
A
NAD+ from Vit B3 (thiacin), FAD from Vit B2 (riboflavin)
19
Q
Only non-protein part of the ETC
A
Coenzyme Q - lipid, ubiquinone
20
Q
Final electron acceptor in ETC
A
Oxygen
21
Q
Protons re enter the mitochondrial matrix in ETC through?
A
Complex V - results in synthesis of ATP, contains ATP Synthase
22
Q
2 components of ATP Synthase
A
F0 - channel where protons pass through, F1 - generates ATP from ADP and Pi
23
Q
Names of the complexes in the ETC
A
I-NADH dehydrogenase, II-Succinate dehydrogenase, III-Ubiquinol, IV-Cytochrome oxidase
24
Q
ETC inhibitor: Dimercaprol
A
Complex III - antidote to lead poisoning
25
ETC inhibitors: Barbiturates
Complex I
26
ETC inhibitors: cyanide
Complex IV
27
ETC inhibitors: carbon monoxide
Complex IV
28
ETC inhibitors: malonate
Complex II
29
Antidote to cyanide poisoning (bitter almond breath)
Amyl nitrite
30
Neonates rely on this protein to produce heat and prevent hypothermia
Thermogenin - through uncoupling
31
Macrolide that acts as an ATP Synthase inhibitor
Oligomycin
32
3 reactive oxygen species
Superoxide (O2), hydrogen peroxide (H2O2), and hydroxyl radical (OH)
33
Defenses against ROS accumulation
Catalase, Peroxidase, Superoxide dismutase
34
Glucose + Glucose
Maltose
35
Glucose + Galactose
Lactose
36
Glucose + Fructose
Sucrose
37
Mitochondrial disease affecting complex I
MELAS - mitochondrial encephalopthy, lactic acidosis, stroke like episodes
38
Mitochondrial disease affecting complex III
Leber's hereditary optic neuropathy
39
Sugar units (disaccharides) are linked by?
Glycosidic bonds
40
Differentiate a proteoglycan from a glycoprotein
Proteoglycan (carbs>proteins), Glycoprotein (protein>carbs)
41
Polysaccharide found in cereals, potatoes, nuts
Starch
42
Polysaccharide of fructose, can be used to check renal function
Inulin
43
Compounds that have the same chemical formula but different structures
Isomers
44
Compounds that differ in configuration around only one specific carbon atom
Epimers
45
Sugar form that is more common in enantiomers
D-sugar
46
2 forms of anomers
Fischer projection (linear), and Haworth projection (ring)
47
Enzyme that can hydrolyze complex carbohydrates to disaccharides
Pancreatic amylase
48
Predominant transporter of glucose and galactose
SGLT 1 - via secondary active transport
49
Transporter for glucose, galactose and fructose
GLUT 5 - via facilitated diffusion
50
Transporter for all sugars
GLUT 2 - via facilitated diffusion
51
2nd messenger of insulin
Tyrosine kinase
52
Protein kinase G acts on what pathway?
cGMP
53
Substrate used in the inositol triphosphate system
Phosphatidylinositol
54
Enzyme that converts ATP to cAMP
Adenylate cyclase
55
Enzyme that degrades cAMP to 5 AMP
cAMP phosphodiesterase
56
GLUT transporter whose function is insulin stimulated uptake of glucose
GLUT 4 - found in muscle and adipose tissue
57
GLUT transported whose function is absorption of glucose in the lumen
GLUT 5 - in the small intestine
58
Where does glycolysis occur?
Cytoplasm of all cells
59
Rate limiting step of Glycolysis
Fructose 6 phosphate _ fructose 1,6 bisphosphate (E: PFK 1)
60
End products of anaerobic and aerobic glycolysis
Lactate (anaerobic), Pyruvate (aerobic)
61
Isozymes that catalyze the phosphorylation of glucose
Hexokinase, Glucokinase
62
Allosteric activator of PFK 1
PFK 2
63
Enzyme that catalyzes the formation of pyruvate
Pyruvate kinase
64
Malate aspartate shuttle is found in the?
Liver, kidney and heart (1 NADH = 3ATP)
65
Glycerol phosphate shuttle is found in the?
Skeletal muscle and brain (1NADH = 2 ATP)
66
What organs convert pyruvate to lactate?
RBCs, lens and cornea of eye, kidney medulla, testes, WBC
67
Most common enzyme defect in glycolysis?
Pyruvate Kinase Deficiency - presentation is chronic hemolytic anemia
68
Central molecule from pyruvate that enters the Kreb's Cycle
Acetyl CoA
69
Congenital lactic acidosis. X linked dominant disease
Pyruvate dehydrogenase deficiency - treat with a ketogenic diet
70
Final common pathway for the aerobic oxidation of all nutrients
TCA/Kreb's Cycle/Citric Acid Cycle
71
Rate limiting step in the Kreb's Cycle
Isocitrate _ alpha ketoglutarate (E: isocitrate dehydrogenase)
72
Fluoroacetate (rat poison) inhibits what step in the Kreb's Cycle?
Citrate _ Isocitrate (E: Aconitase)
73
Arsenite inhibits what step in the Kreb's Cycle?
Alpha ketoglutarate _ Succinyl CoA (E: alpha ketoglutarate dehydrogenase)
74
Where does gluconeogenesis occur?
90 % liver, 10% kidney
75
Rate limiting step in Gluconeogenesis
Fructose 1,6 bisphosphate _ Fructose 6 phosphate (E: fructose 1,6 bisphosphatase)
76
Cycle that converts lactate to glucose via hepatic gluconeogenesis
Cori cycle - energy expense of 4 ATPs
77
Carboxylases require this as a co-factor
Biotin
78
Rate limiting step in the Cori Cycle
Fructose 1,6 bisphosphate _ fructose 6 phosphate (E: fructose 1, 6 bisphosphatase)
79
What are the dual functions of fructose 2,6 bisphosphate
Promotes glycolysis and inhibits gluconeogenesis
80
What enzyme does muscle lack to produce glucose?
Glucose 6 phosphatase
81
Blood concentration of glucose resulting to glucosuria
>180mg/dL
82
Where is glycogen stored?
Liver and muscle
83
Rate limiting step in Glycogenesis
Elongation of glycogen - addition of alpha 1_4 bonds (E: glycogen synthase)
84
Rate limiting step of Glycogenolysis
Breaking of alpha (1_4) bonds (E: glycogen phosphorylase)
85
Enzyme used in the lysosomal degradation of glycogen
Alpha(1_4) glucosidase or acid maltase
86
Glucose 6 phosphatase deficiency (Glycogen storage disease)
Type I: Von Gierke's - hepatomegaly, hypoglycemia, lactic acidosis
87
Acid maltase deficiency (Glycogen storage disease)
Type II: Pompe's - cardiomegaly and HF
88
Deficiency in debranching enzyme (Glycogen storage disease)
Type III: Cori's disease - milder form of type I
89
Deficiency in skeletal muscle glycogen phosphorylase (Glycogen storage disease)
Type V: McArdle's disease
90
True or false: Hexokinase has a greater affinity for glucose
True
91
Enzyme that phosphorylates galactose
Galactose _ Galactose 1 phosphate (E: Galactokinase or Hexokinase)
92
Enzyme deficient in Classic Galactosemia
Galactose 1-P uridyltransferase
93
Autosomal recessive disorder where there is an accumulation of Galactitol
Classic Galactosemia - cataracts, hepatosplenomegaly and mental retardation
94
The activated form of galactose
UDP-galactose
95
Differentiate Aldolase A from Aldolase B
Aldolase A - for glycolysis, Aldolase B - for fructose metabolism
96
Benign condition, only presentation is fructose in blood and urine
Essential fructosuria - deficiency in fructokinase
97
Autosomal recessive condition where there is a deficiency of Aldolase B
Fructose intolerance - increased fructose 1 P, dec phosphate/glycogenolysis/gluconeogenesis
98
Product responsible for the complications of DM
Sorbitol - attracts water
99
Enzyme found in seminal vesicles that converts sorbitol to fructose
Sorbitol dehydrogenase
100
Rate limiting step on the Pentose Phosphate Pathway
Glucose 6 phosphate _ 6 Phosphogluconate (E: Glucose 6 P dehydrogenase)
101
Vitamin required as a co-factor in Transketolases
Vit B1 (Thiamine) - part of the reversible non oxidative phase 2 of Pentose phosphate pathway
102
Product of the Pentose Phosphate Pathway that is used in the synthesis of nucleotides
Ribose 5 phosphate
103
Most common disease producing enzyme abnormality in humans
G6PD Deficiency - dec NADPH in RBCs and dec activity of glutathione
104
Altered Hgb that precipitates within RBCs in G6PD Deficiency
Heinz bodies
105
NADPH oxidase deficiency that leads to increased incidence of infections with Catalase (+) bacteria
Chronic Granulomatous Disease
106
What kind of fatty acids are associated with increased risk of cardiovascular disease?
Trans and saturated fatty acids
107
Essential FAs that cannot be synthesized in the body
Linoleic acid, Linolenic acid
108
Precursor of arachidonic acid that is essential in prostaglandin synthesis
Linoleic acid - essential FA
109
Rate limiting step in FA Synthesis
Acetyl CoA + ATP _ Malonyl CoA (E: Acetyl CoA carboxylase)
110
Transfer of Acetyl CoA from the mitochondria to the cytoplasm occurs through a?
Citrate shuttle
111
Where is Acetyl CoA produced?
Mitochondrial matrix
112
Main storage form of fatty acids
Triacylglycerols
113
Enzyme that hydrolyzes TAGs to yield FFAs and glycerol
Hormone sensitive lipase
114
Rate limiting step in Beta Oxidation of FAs
Fatty acyl CoA + Carnitine _ fatty acyl carnitine + CoA (E: carnitine acyltransferase)
115
Long chain FAs is brought to the inner mitochondrial membrane for Beta oxidation of FAs through?
Carnitine shuttle
116
Organelle that oxidizes very long chain FAs (20-22 carbons)
Peroxisomes
117
Can manifest as Sudden Infant Death Syndrome due to decreased FA oxidation
Medium chain fatty acyl CoA dehydrogenase - no ATP to support gluconeogenesis, treat with IV glucose
118
Toxin in Jamaican Vomiting Sickness
Hypoglycin - unripe fruit of Akee tree
119
Neurologic disorder due to accumulation of Phytanic acid that blocks beta oxidation
Refsum's Disease
120
Rare inherited absence of peroxisomes in all tissues
Zellweger's Syndrome - liver dysfunction, mental retardation, craniofacial dysmorphism
121
Where does ketogenesis occur?
Liver mitochondria
122
Product of ketogenesis that is not used as fuel
Acetone
123
Rate limiting step in ketogenesis
Acetoacetyl CoA + acetyl CoA _ HMG CoA (E: HMG CoA synthase)
124
Liver cannot convert acetoacetate to acetyl CoA because it lacks which enzyme?
Succinyl-CoA acetoacetyl-CoA transferase (thiophorase)
125
Urine test for ketones
Nitroprusside test
126
Where dows cholesterol synthesis occur?
Cytosol and smooth ER of liver and intestines
127
Rate limiting step in cholesterol synthesis
HMG CoA _ Mevalonate (E: HMG CoA reductase)
128
Intermediate in Cholesterol synthesis that is used for synthesis of Coenzyme Q for the ETC
Farnesyl pyrophosphate
129
How does acetyl CoA reach the cytosol for cholesterol biosynthesis?
Citrate shuttle
130
Primary means of excreting cholesterol
Bile salts (bile acid + glycine or taurine)
131
Where does enterohepatic circulation occur?
95% of bile is reabsorbed in terminal ileum
132
Mother hormone in steroid hormone synthesis
ACTH
133
Rate limiting step in steroid hormone synthesis
Cholesterol _ Pregnenolone (E: desmolase)
134
Protein secreted by enterocytes to make lipids more soluble in blood
Apoprotein B 48
135
Enzyme that breaks down triglycerides to FA and glycerol
Lipoprotein lipase
136
Apoprotein in chylomicron that activates lipoprotein lipase
Apo C-II
137
Apoprotein in VLDL secreted by the liver
Apo B-100
138
Apoprotein in HDL that activates Lecithin Cholesterol Acyltransferase (LCAT) to produce cholesterol esters
Apo A-1
139
Picks up cholesterol from HDL to become LDL
IDL
140
Delivers cholesterol into cells using Apo B 100
LDL
141
Picks up cholesterol accumulating in blood vessels and delivers it to liver via Scavenger Receptor (SR-B1)
HDL
142
Deficient in Abetalipoproteinemia resulting to intestinal malabsorption
Apo B 48 and Apo B 100 - no chylomicron, no VLDL/LDL
143
Deficiency in lipoprotein lipase leading to high VLDL and chylomicron with low LDL and HDL
Type I Familial lipoprotein lipase - xanthomas and pancreatitis
144
Deficiency in LDL receptors leading to high LDL
Type II Familial hypercholesterolemia - risk for atherosclerosis and coronary heart disease
145
Phospholipid important in nervous transmission as Acetylcholine
Phosphatidylcholine - most abundant phospholipid
146
Phospholipid that is a major component of lung surfactant
Dipalmitoylphosphatidylcholine (DPPC) or lecithin
147
Phospholipid that is the source of 2nd messengers
Phosphatidylinositol
148
Phospholipid found only in mitochondria an is essential for its function
Cardiolipin
149
Cardiolipin is antigenic. It reacts with antibodies produced?
Treponema pallidum (syphylis)
150
Only significant sphingolipid in humans, important part of myelin sheath
Sphingomyelin
151
Deficiency in Hexosaminidase A
Tay-Sach's disease - cherry red macula, MR and hypotonia
152
Deficiency in alpha Galactosidase
Fabry's disease - X linked recessive, rash, renal failure
153
Deficiency in beta glucosidase
Gaucher's disease - hepatosplenomegaly and erosion of long bones
154
Deficiency in sphingomyelinase
Niemann-Pick disease resulting to hepatosplenomegaly
155
Dietary precursor of Eicosanoids
Linoleic acid
156
Immediate precursor of Eicosanoids
Arachidonic acid
157
Eicosanoid produced by blood vessel walls
Prostacyclin - inhibits platelet aggregation
158
Set of all proteins expressed by an individual cell at a particular time
Proteome
159
Amino Acid that accumulated in Maple syrup disease
Branched chain AAs - valine, leucine, isoleucine
160
AA with the smallest side chain that is used in the first step of heme synthesis
Glycine - major inhibitory neurotransmitter in the spinal cord
161
Enzyme deficient in PKU leading to an increase in amounts of phenylalanine
Phenylalanine hydroxylase
162
AA that is the precursor of niacin, serotonin and melatonin
Tryptophan - has the largest side chain
163
Covalent disulfide bonds combine 2 cysteines to form?
Cystine - found in keratin
164
AA that is a precursor of thyroxine and melanin
Tyrosine
165
Sited for O-linked glycosylation in Golgi apparatus
Serine and Threonine
166
Site for N-linked glycosylation in ER
Asparagine
167
AA that is a major carrier of nitrogen to the liver from peripheral tissues
Glutamine
168
AA that is the major precursor for GABA and glutathione
Glutamate
169
AA that is the precursor of histamine
Histidine
170
AA that is the precursor of creatinine, urea and NO
Arginine
171
Configuration of all AAs in proteins
L-configuration
172
Attach alpha amino group of one AA to the alpha carbonyl group of another
Peptide bonds -trans configuration
173
Secondary structures of proteins are stabilized by?
Hydrogen bonds
174
Most common protein secondary structure
Alpha helix - R handed spiral with polypeptide backbone core
175
3 dimensional shape of a protein that have a specific function
Tertiary structure - stabilized by disulfide bonds, hydrogen bonds and ionic bonds
176
Structure of proteins consisting of more than 1 polypeptide chain
Quaternary structure - non covalent bonds
177
What are the normal and abnormal proteins in Prion Disease?
PrPc (normal-rich in alpha helices), PrPsc (abnormal-rich in beta sheets)
178
Complex of protoporphyrin IX and ferrous iron
Heme - reversibly binds oxygen in myoglobin and hemoglobin
179
Major transported of CO2 in the blood
Bicarbonate (75%)
180
Symptoms of chocolate cyanosis, headache and dyspnea
Methemoglobinemia - increased affinity of ferric for cyanide (stops complex IV of ETC)
181
Treatment for carboxyhemoglobin
Hb is cherry pink in color, treat with 100% O2 to displace carbon monoxide
182
Most common mutation in hereditary spherocytosis
Ankyrin - splenectomy for symptomatic patients
183
Point mutation in both genes coding for the beta chain that results in a valine rather than a glutamate
Sickle cell disease - homozygous recessive disorder
184
Disease with a single AA substitution in the 6th position of the beta globin chain where lysine is substituted for glutamate
Hemoglobin C disease - mild hemolytic anemia
185
When do symptoms of anemia appear in Alpha and Beta thalassemia
Alpha-at birth, Beta-after birth
186
Most abundant protein in the body
Collagen -triple helix stabilized by hydrogen bonds
187
Disease with hyperextensible skin, bleeding tendencies, hypermobile joints and increased risk for berry aneurysms
Ehlers-Danlos Syndrome - Type III collagen
188
Disease: multiple fractures, blue sclerae, hearing loss, and dental imperfections
Osteogenesis imperfecta or Brittle Bone Syndrome - collagen type I
189
Vit C deficiency leads to decreased cross linking of collagen fibers
Scurvy - sore spongy gums, loose teeth, poor wound healing
190
Syndrome: hematuria, ESRD, sensorineural hearing loss
Alport syndrome - collagen type IV
191
Kinky hair and growth retardation due to a deficiency in copper required by Lysyl oxidase
Menke's Syndrome
192
Deficiency in Type VII collagen
Epidermolysis Bullosa
193
Marfan syndrome is autosomal dominant and presents with a mutation in this gene
Fibrillin gene
194
Most powerful pancreatic enzyme that digests proteins
Trypsin
195
Major disposal form of nitrogen
Urea
196
Vitamin needed for Transamination (removal of Nitrogen)
Vitamin B6 - pyridoxal phosphate
197
Enzyme that oxidizes and deaminates glutamate to yield free ammonia that is used to make urea
Glutamate dehydrogenase
198
Enzyme: Glutamate + Ammonia _ Glutamine
Glutamine Synthetase
199
Enzyme: Pyruvate + Glutamate _ Alanine + Alpha Ketoglutarate
ALT or SGPT
200
Pathway for removal of nitrogenous waste products in the body
Urea cycle - happens only in the liver
201
Rate limiting step of Urea Cycle
CO2 + NH3 _ Carbamoyl phosphate (E: Carbamoyl phosphate synthetase I)
202
Only product in the Urea Cycle that can penetrate the mitochondrial membrane
Citrulline
203
Disease: hyperammonemia, elevated glutamine and decreased BUN
Hereditary hyperammonemia - lethargy, vomitig, hyperventilation, convulsions, coma
