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