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Flashcards in biochem Deck (203):
1

Water forms Hydrogen Bonds with?

Sulfur, oxygen and nitrogen atom (SON)

2

Define amphoteric and amphipathic

Amphoteric - acts as both an acid and a base, Amphipathic - has hydrophilic an hydrophobic parts

3

What is the normal pH?

7.35 - 7.45

4

DKA Criteria

Diabetic, Ketosis (+) urine ketones, ABG that documents acidosis

5

Important physiologic buffers

Bicarbonate - extracellular, Proteins - intracellular

6

Distinct versions of a given enzyme that catalyze the same reactions

Isozymes

7

Enzymes that catalyze the joining together of 2 molecules coupled to the hydrolysis of ATP

Ligases

8

Refers to the enzyme and its co-factor

Holoenzyme

9

True or false: enzymes that follow the Michaelis-Menten equation have a hyperbolic curve

True - equation describes how reaction velocity varies with substrate concentration

10

Reversal of competitive and non competitive inhibitors

Competitive - increase substrate, Noncompetitive - increase enzyme

11

Vmax change during inhibition

Competitive - not changed, Non competitive- lowered

12

What enzyme markers would best confirm a re-infarct?

CK-MB

13

Can be used to predict whether a reaction is spontaneous or not

Change in free energy

14

Equation of Change in Free Energy

15

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

ATP,

16

Differentiate oxygen phosphorylation from substrate level phosphorylation

Oxidative phosphorylation - mitochondria, oxygen needed. Substrate level phosphorylation - cytoplasm and mitochondria, oxygen not needed

17

Where does the ETC occur?

Inner mitochondrial membrane

18

2 electron carriers in the ETC

NAD+ from Vit B3 (thiacin), FAD from Vit B2 (riboflavin)

19

Only non-protein part of the ETC

Coenzyme Q - lipid, ubiquinone

20

Final electron acceptor in ETC

Oxygen

21

Protons re enter the mitochondrial matrix in ETC through?

Complex V - results in synthesis of ATP, contains ATP Synthase

22

2 components of ATP Synthase

F0 - channel where protons pass through, F1 - generates ATP from ADP and Pi

23

Names of the complexes in the ETC

I-NADH dehydrogenase, II-Succinate dehydrogenase, III-Ubiquinol, IV-Cytochrome oxidase

24

ETC inhibitor: Dimercaprol

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