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Flashcards in biochem Deck (203)
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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

14
Q

Equation of Change in Free Energy

A
15
Q

Energy currency of the cell. It’s hydrolysis yields a large

A

ATP,

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
Q

ETC inhibitors: Barbiturates

A

Complex I

26
Q

ETC inhibitors: cyanide

A

Complex IV

27
Q

ETC inhibitors: carbon monoxide

A

Complex IV

28
Q

ETC inhibitors: malonate

A

Complex II

29
Q

Antidote to cyanide poisoning (bitter almond breath)

A

Amyl nitrite

30
Q

Neonates rely on this protein to produce heat and prevent hypothermia

A

Thermogenin - through uncoupling

31
Q

Macrolide that acts as an ATP Synthase inhibitor

A

Oligomycin

32
Q

3 reactive oxygen species

A

Superoxide (O2), hydrogen peroxide (H2O2), and hydroxyl radical (OH)

33
Q

Defenses against ROS accumulation

A

Catalase, Peroxidase, Superoxide dismutase

34
Q

Glucose + Glucose

A

Maltose

35
Q

Glucose + Galactose

A

Lactose

36
Q

Glucose + Fructose

A

Sucrose

37
Q

Mitochondrial disease affecting complex I

A

MELAS - mitochondrial encephalopthy, lactic acidosis, stroke like episodes

38
Q

Mitochondrial disease affecting complex III

A

Leber’s hereditary optic neuropathy

39
Q

Sugar units (disaccharides) are linked by?

A

Glycosidic bonds

40
Q

Differentiate a proteoglycan from a glycoprotein

A

Proteoglycan (carbs>proteins), Glycoprotein (protein>carbs)

41
Q

Polysaccharide found in cereals, potatoes, nuts

A

Starch

42
Q

Polysaccharide of fructose, can be used to check renal function

A

Inulin

43
Q

Compounds that have the same chemical formula but different structures

A

Isomers

44
Q

Compounds that differ in configuration around only one specific carbon atom

A

Epimers

45
Q

Sugar form that is more common in enantiomers

A

D-sugar

46
Q

2 forms of anomers

A

Fischer projection (linear), and Haworth projection (ring)

47
Q

Enzyme that can hydrolyze complex carbohydrates to disaccharides

A

Pancreatic amylase

48
Q

Predominant transporter of glucose and galactose

A

SGLT 1 - via secondary active transport

49
Q

Transporter for glucose, galactose and fructose

A

GLUT 5 - via facilitated diffusion

50
Q

Transporter for all sugars

A

GLUT 2 - via facilitated diffusion

51
Q

2nd messenger of insulin

A

Tyrosine kinase

52
Q

Protein kinase G acts on what pathway?

A

cGMP

53
Q

Substrate used in the inositol triphosphate system

A

Phosphatidylinositol

54
Q

Enzyme that converts ATP to cAMP

A

Adenylate cyclase

55
Q

Enzyme that degrades cAMP to 5 AMP

A

cAMP phosphodiesterase

56
Q

GLUT transporter whose function is insulin stimulated uptake of glucose

A

GLUT 4 - found in muscle and adipose tissue

57
Q

GLUT transported whose function is absorption of glucose in the lumen

A

GLUT 5 - in the small intestine

58
Q

Where does glycolysis occur?

A

Cytoplasm of all cells

59
Q

Rate limiting step of Glycolysis

A

Fructose 6 phosphate ? fructose 1,6 bisphosphate (E: PFK 1)

60
Q

End products of anaerobic and aerobic glycolysis

A

Lactate (anaerobic), Pyruvate (aerobic)

61
Q

Isozymes that catalyze the phosphorylation of glucose

A

Hexokinase, Glucokinase

62
Q

Allosteric activator of PFK 1

A

PFK 2

63
Q

Enzyme that catalyzes the formation of pyruvate

A

Pyruvate kinase

64
Q

Malate aspartate shuttle is found in the?

A

Liver, kidney and heart (1 NADH = 3ATP)

65
Q

Glycerol phosphate shuttle is found in the?

A

Skeletal muscle and brain (1NADH = 2 ATP)

66
Q

What organs convert pyruvate to lactate?

A

RBCs, lens and cornea of eye, kidney medulla, testes, WBC

67
Q

Most common enzyme defect in glycolysis?

A

Pyruvate Kinase Deficiency - presentation is chronic hemolytic anemia

68
Q

Central molecule from pyruvate that enters the Kreb’s Cycle

A

Acetyl CoA

69
Q

Congenital lactic acidosis. X linked dominant disease

A

Pyruvate dehydrogenase deficiency - treat with a ketogenic diet

70
Q

Final common pathway for the aerobic oxidation of all nutrients

A

TCA/Kreb’s Cycle/Citric Acid Cycle

71
Q

Rate limiting step in the Kreb’s Cycle

A

Isocitrate ? alpha ketoglutarate (E: isocitrate dehydrogenase)

72
Q

Fluoroacetate (rat poison) inhibits what step in the Kreb’s Cycle?

A

Citrate ? Isocitrate (E: Aconitase)

73
Q

Arsenite inhibits what step in the Kreb’s Cycle?

A

Alpha ketoglutarate ? Succinyl CoA (E: alpha ketoglutarate dehydrogenase)

74
Q

Where does gluconeogenesis occur?

A

90 % liver, 10% kidney

75
Q

Rate limiting step in Gluconeogenesis

A

Fructose 1,6 bisphosphate ? Fructose 6 phosphate (E: fructose 1,6 bisphosphatase)

76
Q

Cycle that converts lactate to glucose via hepatic gluconeogenesis

A

Cori cycle - energy expense of 4 ATPs

77
Q

Carboxylases require this as a co-factor

A

Biotin

78
Q

Rate limiting step in the Cori Cycle

A

Fructose 1,6 bisphosphate ? fructose 6 phosphate (E: fructose 1, 6 bisphosphatase)

79
Q

What are the dual functions of fructose 2,6 bisphosphate

A

Promotes glycolysis and inhibits gluconeogenesis

80
Q

What enzyme does muscle lack to produce glucose?

A

Glucose 6 phosphatase

81
Q

Blood concentration of glucose resulting to glucosuria

A

> 180mg/dL

82
Q

Where is glycogen stored?

A

Liver and muscle

83
Q

Rate limiting step in Glycogenesis

A

Elongation of glycogen - addition of alpha 1?4 bonds (E: glycogen synthase)

84
Q

Rate limiting step of Glycogenolysis

A

Breaking of alpha (1?4) bonds (E: glycogen phosphorylase)

85
Q

Enzyme used in the lysosomal degradation of glycogen

A

Alpha(1?4) glucosidase or acid maltase

86
Q

Glucose 6 phosphatase deficiency (Glycogen storage disease)

A

Type I: Von Gierke’s - hepatomegaly, hypoglycemia, lactic acidosis

87
Q

Acid maltase deficiency (Glycogen storage disease)

A

Type II: Pompe’s - cardiomegaly and HF

88
Q

Deficiency in debranching enzyme (Glycogen storage disease)

A

Type III: Cori’s disease - milder form of type I

89
Q

Deficiency in skeletal muscle glycogen phosphorylase (Glycogen storage disease)

A

Type V: McArdle’s disease

90
Q

True or false: Hexokinase has a greater affinity for glucose

A

TRUE

91
Q

Enzyme that phosphorylates galactose

A

Galactose ? Galactose 1 phosphate (E: Galactokinase or Hexokinase)

92
Q

Enzyme deficient in Classic Galactosemia

A

Galactose 1-P uridyltransferase

93
Q

Autosomal recessive disorder where there is an accumulation of Galactitol

A

Classic Galactosemia - cataracts, hepatosplenomegaly and mental retardation

94
Q

The activated form of galactose

A

UDP-galactose

95
Q

Differentiate Aldolase A from Aldolase B

A

Aldolase A - for glycolysis, Aldolase B - for fructose metabolism

96
Q

Benign condition, only presentation is fructose in blood and urine

A

Essential fructosuria - deficiency in fructokinase

97
Q

Autosomal recessive condition where there is a deficiency of Aldolase B

A

Fructose intolerance - increased fructose 1 P, dec phosphate/glycogenolysis/gluconeogenesis

98
Q

Product responsible for the complications of DM

A

Sorbitol - attracts water

99
Q

Enzyme found in seminal vesicles that converts sorbitol to fructose

A

Sorbitol dehydrogenase

100
Q

Rate limiting step on the Pentose Phosphate Pathway

A

Glucose 6 phosphate ? 6 Phosphogluconate (E: Glucose 6 P dehydrogenase)

101
Q

Vitamin required as a co-factor in Transketolases

A

Vit B1 (Thiamine) - part of the reversible non oxidative phase 2 of Pentose phosphate pathway

102
Q

Product of the Pentose Phosphate Pathway that is used in the synthesis of nucleotides

A

Ribose 5 phosphate

103
Q

Most common disease producing enzyme abnormality in humans

A

G6PD Deficiency - dec NADPH in RBCs and dec activity of glutathione

104
Q

Altered Hgb that precipitates within RBCs in G6PD Deficiency

A

Heinz bodies

105
Q

NADPH oxidase deficiency that leads to increased incidence of infections with Catalase (+) bacteria

A

Chronic Granulomatous Disease

106
Q

What kind of fatty acids are associated with increased risk of cardiovascular disease?

A

Trans and saturated fatty acids

107
Q

Essential FAs that cannot be synthesized in the body

A

Linoleic acid, Linolenic acid

108
Q

Precursor of arachidonic acid that is essential in prostaglandin synthesis

A

Linoleic acid - essential FA

109
Q

Rate limiting step in FA Synthesis

A

Acetyl CoA + ATP ? Malonyl CoA (E: Acetyl CoA carboxylase)

110
Q

Transfer of Acetyl CoA from the mitochondria to the cytoplasm occurs through a?

A

Citrate shuttle

111
Q

Where is Acetyl CoA produced?

A

Mitochondrial matrix

112
Q

Main storage form of fatty acids

A

Triacylglycerols

113
Q

Enzyme that hydrolyzes TAGs to yield FFAs and glycerol

A

Hormone sensitive lipase

114
Q

Rate limiting step in Beta Oxidation of FAs

A

Fatty acyl CoA + Carnitine ? fatty acyl carnitine + CoA (E: carnitine acyltransferase)

115
Q

Long chain FAs is brought to the inner mitochondrial membrane for Beta oxidation of FAs through?

A

Carnitine shuttle

116
Q

Organelle that oxidizes very long chain FAs (20-22 carbons)

A

Peroxisomes

117
Q

Can manifest as Sudden Infant Death Syndrome due to decreased FA oxidation

A

Medium chain fatty acyl CoA dehydrogenase - no ATP to support gluconeogenesis, treat with IV glucose

118
Q

Toxin in Jamaican Vomiting Sickness

A

Hypoglycin - unripe fruit of Akee tree

119
Q

Neurologic disorder due to accumulation of Phytanic acid that blocks beta oxidation

A

Refsum’s Disease

120
Q

Rare inherited absence of peroxisomes in all tissues

A

Zellweger’s Syndrome - liver dysfunction, mental retardation, craniofacial dysmorphism

121
Q

Where does ketogenesis occur?

A

Liver mitochondria

122
Q

Product of ketogenesis that is not used as fuel

A

Acetone

123
Q

Rate limiting step in ketogenesis

A

Acetoacetyl CoA + acetyl CoA ? HMG CoA (E: HMG CoA synthase)

124
Q

Liver cannot convert acetoacetate to acetyl CoA because it lacks which enzyme?

A

Succinyl-CoA acetoacetyl-CoA transferase (thiophorase)

125
Q

Urine test for ketones

A

Nitroprusside test

126
Q

Where dows cholesterol synthesis occur?

A

Cytosol and smooth ER of liver and intestines

127
Q

Rate limiting step in cholesterol synthesis

A

HMG CoA ? Mevalonate (E: HMG CoA reductase)

128
Q

Intermediate in Cholesterol synthesis that is used for synthesis of Coenzyme Q for the ETC

A

Farnesyl pyrophosphate

129
Q

How does acetyl CoA reach the cytosol for cholesterol biosynthesis?

A

Citrate shuttle

130
Q

Primary means of excreting cholesterol

A

Bile salts (bile acid + glycine or taurine)

131
Q

Where does enterohepatic circulation occur?

A

95% of bile is reabsorbed in terminal ileum

132
Q

Mother hormone in steroid hormone synthesis

A

ACTH

133
Q

Rate limiting step in steroid hormone synthesis

A

Cholesterol ? Pregnenolone (E: desmolase)

134
Q

Protein secreted by enterocytes to make lipids more soluble in blood

A

Apoprotein B 48

135
Q

Enzyme that breaks down triglycerides to FA and glycerol

A

Lipoprotein lipase

136
Q

Apoprotein in chylomicron that activates lipoprotein lipase

A

Apo C-II

137
Q

Apoprotein in VLDL secreted by the liver

A

Apo B-100

138
Q

Apoprotein in HDL that activates Lecithin Cholesterol Acyltransferase (LCAT) to produce cholesterol esters

A

Apo A-1

139
Q

Picks up cholesterol from HDL to become LDL

A

IDL

140
Q

Delivers cholesterol into cells using Apo B 100

A

LDL

141
Q

Picks up cholesterol accumulating in blood vessels and delivers it to liver via Scavenger Receptor (SR-B1)

A

HDL

142
Q

Deficient in Abetalipoproteinemia resulting to intestinal malabsorption

A

Apo B 48 and Apo B 100 - no chylomicron, no VLDL/LDL

143
Q

Deficiency in lipoprotein lipase leading to high VLDL and chylomicron with low LDL and HDL

A

Type I Familial lipoprotein lipase - xanthomas and pancreatitis

144
Q

Deficiency in LDL receptors leading to high LDL

A

Type II Familial hypercholesterolemia - risk for atherosclerosis and coronary heart disease

145
Q

Phospholipid important in nervous transmission as Acetylcholine

A

Phosphatidylcholine - most abundant phospholipid

146
Q

Phospholipid that is a major component of lung surfactant

A

Dipalmitoylphosphatidylcholine (DPPC) or lecithin

147
Q

Phospholipid that is the source of 2nd messengers

A

Phosphatidylinositol

148
Q

Phospholipid found only in mitochondria an is essential for its function

A

Cardiolipin

149
Q

Cardiolipin is antigenic. It reacts with antibodies produced?

A

Treponema pallidum (syphylis)

150
Q

Only significant sphingolipid in humans, important part of myelin sheath

A

Sphingomyelin

151
Q

Deficiency in Hexosaminidase A

A

Tay-Sach’s disease - cherry red macula, MR and hypotonia

152
Q

Deficiency in alpha Galactosidase

A

Fabry’s disease - X linked recessive, rash, renal failure

153
Q

Deficiency in beta glucosidase

A

Gaucher’s disease - hepatosplenomegaly and erosion of long bones

154
Q

Deficiency in sphingomyelinase

A

Niemann-Pick disease resulting to hepatosplenomegaly

155
Q

Dietary precursor of Eicosanoids

A

Linoleic acid

156
Q

Immediate precursor of Eicosanoids

A

Arachidonic acid

157
Q

Eicosanoid produced by blood vessel walls

A

Prostacyclin - inhibits platelet aggregation

158
Q

Set of all proteins expressed by an individual cell at a particular time

A

Proteome

159
Q

Amino Acid that accumulated in Maple syrup disease

A

Branched chain AAs - valine, leucine, isoleucine

160
Q

AA with the smallest side chain that is used in the first step of heme synthesis

A

Glycine - major inhibitory neurotransmitter in the spinal cord

161
Q

Enzyme deficient in PKU leading to an increase in amounts of phenylalanine

A

Phenylalanine hydroxylase

162
Q

AA that is the precursor of niacin, serotonin and melatonin

A

Tryptophan - has the largest side chain

163
Q

Covalent disulfide bonds combine 2 cysteines to form?

A

Cystine - found in keratin

164
Q

AA that is a precursor of thyroxine and melanin

A

Tyrosine

165
Q

Sited for O-linked glycosylation in Golgi apparatus

A

Serine and Threonine

166
Q

Site for N-linked glycosylation in ER

A

Asparagine

167
Q

AA that is a major carrier of nitrogen to the liver from peripheral tissues

A

Glutamine

168
Q

AA that is the major precursor for GABA and glutathione

A

Glutamate

169
Q

AA that is the precursor of histamine

A

Histidine

170
Q

AA that is the precursor of creatinine, urea and NO

A

Arginine

171
Q

Configuration of all AAs in proteins

A

L-configuration

172
Q

Attach alpha amino group of one AA to the alpha carbonyl group of another

A

Peptide bonds -trans configuration

173
Q

Secondary structures of proteins are stabilized by?

A

Hydrogen bonds

174
Q

Most common protein secondary structure

A

Alpha helix - R handed spiral with polypeptide backbone core

175
Q

3 dimensional shape of a protein that have a specific function

A

Tertiary structure - stabilized by disulfide bonds, hydrogen bonds and ionic bonds

176
Q

Structure of proteins consisting of more than 1 polypeptide chain

A

Quaternary structure - non covalent bonds

177
Q

What are the normal and abnormal proteins in Prion Disease?

A

PrPc (normal-rich in alpha helices), PrPsc (abnormal-rich in beta sheets)

178
Q

Complex of protoporphyrin IX and ferrous iron

A

Heme - reversibly binds oxygen in myoglobin and hemoglobin

179
Q

Major transported of CO2 in the blood

A

Bicarbonate (75%)

180
Q

Symptoms of chocolate cyanosis, headache and dyspnea

A

Methemoglobinemia - increased affinity of ferric for cyanide (stops complex IV of ETC)

181
Q

Treatment for carboxyhemoglobin

A

Hb is cherry pink in color, treat with 100% O2 to displace carbon monoxide

182
Q

Most common mutation in hereditary spherocytosis

A

Ankyrin - splenectomy for symptomatic patients

183
Q

Point mutation in both genes coding for the beta chain that results in a valine rather than a glutamate

A

Sickle cell disease - homozygous recessive disorder

184
Q

Disease with a single AA substitution in the 6th position of the beta globin chain where lysine is substituted for glutamate

A

Hemoglobin C disease - mild hemolytic anemia

185
Q

When do symptoms of anemia appear in Alpha and Beta thalassemia

A

Alpha-at birth, Beta-after birth

186
Q

Most abundant protein in the body

A

Collagen -triple helix stabilized by hydrogen bonds

187
Q

Disease with hyperextensible skin, bleeding tendencies, hypermobile joints and increased risk for berry aneurysms

A

Ehlers-Danlos Syndrome - Type III collagen

188
Q

Disease: multiple fractures, blue sclerae, hearing loss, and dental imperfections

A

Osteogenesis imperfecta or Brittle Bone Syndrome - collagen type I

189
Q

Vit C deficiency leads to decreased cross linking of collagen fibers

A

Scurvy - sore spongy gums, loose teeth, poor wound healing

190
Q

Syndrome: hematuria, ESRD, sensorineural hearing loss

A

Alport syndrome - collagen type IV

191
Q

Kinky hair and growth retardation due to a deficiency in copper required by Lysyl oxidase

A

Menke’s Syndrome

192
Q

Deficiency in Type VII collagen

A

Epidermolysis Bullosa

193
Q

Marfan syndrome is autosomal dominant and presents with a mutation in this gene

A

Fibrillin gene

194
Q

Most powerful pancreatic enzyme that digests proteins

A

Trypsin

195
Q

Major disposal form of nitrogen

A

Urea

196
Q

Vitamin needed for Transamination (removal of Nitrogen)

A

Vitamin B6 - pyridoxal phosphate

197
Q

Enzyme that oxidizes and deaminates glutamate to yield free ammonia that is used to make urea

A

Glutamate dehydrogenase

198
Q

Enzyme: Glutamate + Ammonia ? Glutamine

A

Glutamine Synthetase

199
Q

Enzyme: Pyruvate + Glutamate ? Alanine + Alpha Ketoglutarate

A

ALT or SGPT

200
Q

Pathway for removal of nitrogenous waste products in the body

A

Urea cycle - happens only in the liver

201
Q

Rate limiting step of Urea Cycle

A

CO2 + NH3 ? Carbamoyl phosphate (E: Carbamoyl phosphate synthetase I)

202
Q

Only product in the Urea Cycle that can penetrate the mitochondrial membrane

A

Citrulline

203
Q

Disease: hyperammonemia, elevated glutamine and decreased BUN

A

Hereditary hyperammonemia - lethargy, vomitig, hyperventilation, convulsions, coma