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Flashcards in Biochemistry Deck (137):
1

I-cell Disease (Mucolipidosis II)

- Defective UDP-N-acetylglucosamine-1-phosphotransferase
- Hydrolases secreted (because mannose is not phosphorylated in golgi)→ misshapen bones, clouded corneas, restricted joints, and hyperplastic gums, “gargoyle facies”

2

Ornithine Transcarbamylase Deficiency

- Urea cycle disorder → hyperammonemia and increased orotic acid excretion in urine
- Treat by limiting protein intake so that excess ammonia is not produced, eat just enough to get essential amino acids
(Carbomoyl Phosphate Synthetase and N-acetyl glutamate are in the step before and will not produce excess orotic acid)

3

N-Acetylglutamate

- Essential to activate carbamoyl phosphate synthase (CPS1) in Urea cycle

4

Dihydrobiopterin Reductase Deficiency

-Low BH4 (which is needed for conversion of tyrosine --> DOPA by tyrosine hydroxylase)
- BH4 needed as cofactor for synthesis of Tyrosine, DOPA, serotonin, and NO
(in pathway for both Phenylalanine and Tryptophan)

5

Menke's Disease

Kinky hair disease, low copper

6

Fructose 2,6 bisphosphate

- Fructose 2,6 bisphosphate activates glycolysis by inducing PFK1 and inhibiting fructose 1,6 bisphosphatase to stop gluconeogenesis
- Fed: PFK2 makes fructose 2,6 and also activates PFK1 to go towards glycolysis
- Starved: FBP makes fructose 2,6 go to fructose 6 towards gluconeogenesis

[Insulin increases Fructose 6P promoting PFK2 activity --> fructose 2,6, bisphosphate and glycosysis]

7

Splice Sites

GT at 5’ (GU in RNA) and AG at 3’

8

Supplementation for Children w/ Measles

Vitamin A

9

Aldose Reductase

Contributes to buildup of product in eye → cataract
- Glucose to sorbitol
- Galactose to galactitol

10

Fructokinase Deficiency vs Aldolase B Deficiency

Fructokinase deficiency: benign fructosuria
Aldose B: severe fructose intolerance w/ hypoglycemia

11

Pyrimidine Dimer Removal by:

Nucleotide Excision Repair

12

Reactions requiring Pyridoxine (B6)

Transamination reactions or Decarboxylation

13

Hartnup Disease

- Defective amino acid transport → diarrhea, dementia, dermatitis (resembles pellagra/niacin deficiency)
- Malabsorption of tryptophan (aromatic neutral AA’s) → aminoaciduria
- Treat with Niacin (B3)

14

Fanconi Syndrome

Generalized aminoaciduria (all amino acids)

15

Calories

Proteins: 4
Carbs: 4
Fats: 9

16

Blotting

SNoW DRoP
- Northern: RNA
- Southern: DNA
- Western: Protein
- Southwestern: DNA binding proteins (e.g. transcription factors, histones, nucleases)

17

Maple Syrup Urine Disase

- Impaired degradation of isoleucine, leucine, and valine
-Burnt sugar smell in diaper

18

Niemann-Pick Disease

- Sphingomyelinase deficiency
- Progressive neurologic deterioration
- Cherry Red Spot

19

Lesch-Nyhan Syndrome

HGPRT deficient → defective pruine salvage → hyperuricemia/gout, self-mutilation, retardation, dystonia
- Because of failure of the purine salvage pathway → de novo purine synthesis must increase to replace the lost bases → PRPP amidotransferase activity will increase

20

GLUT4 and GLUT2 Transporter

GLUT4 transporter: insulin dependent (increases translocation to cell membrane); skeletal muscle and adipose tissue
GLUT2: regulates insulin release; hepatocytes

21

Niacin (B3)

- NAD+ constituent
- Tryptophan is a precursor
- Flushing

22

Homocystinuria

- May resemble Marfan’s (long limbs, tall, subluxation of lenses) but also has mental retardation
- Buildup of methionine (homocysteine is remethylated by salvage pathway)
- Cystathionine synthase deficiency

23

RNA Polymerases

I: rRNA
II: mRNA
III: tRNA

24

Mitochondrial Myopathy

Ragged red fibers and Gomori trichrome
- Mitochondrial inheritance (maternal); heteroplasmy

25

Kreb's Cycle: NADH, FADH, GTP production

NADH made:
- Isocitrate to a-ketoglutarate
- a-ketoglutarate to succinyl coA
- Malate to oxaloacetate
FADH made:
- Succinate to fumarate
GTP made:
- Succinyl CoA to Succinate

26

Exclusively Ketogenic Amino Acids

Lysine and Leucine

27

Amino Acid binding site on tRNA

CCA at 3' end

28

Apolipoprotein: A1

LCAT activation (esterification of cholesterol)

29

Apolipoprotein: B48

Chylomicron assembly and secretion by intestine
Produced by intestinal enterocytes (Truncated form of ApoB100)

30

Apolipoprotein: B100

LDL uptake by extrahepatic cells
Produced by hepatocytes

31

Apolipoprotein: CII

LPL activation

32

Apolipoprotein: E3 & E4

VLDL and chylomicron remnant uptake by liver

33

mRNA Stop Codons

UGA, UAG, UAA
- Binds releasing factor
- Last amino acid will be the codon before

34

Thiamine (B1) required for:

- Pyruvate dehydrogenase
- Transketolase (part of PPP)
- a-ketoglutarate dehydrogenase
- Branched-chain

35

PPP (Pentose Phosphate Pathway)

- HMP Shunt
- Takes place in the cytosol (e.g. Ketolase)
- G6PD enzyme
- Produces NADPH

36

Mitochondrial Processes

- Beta oxidation of FAs
- Ketogenesis
- Krebs cycle
- Parts of urea cycles
- Pyruvate carboxylation
- Parts of heme synthesis

37

Phenylalanine Conversions

Phenylalanine (via tyrosine hydroxylase) → tyrosine:
- Tyrosine → DOPA → dopamine
- Tyrosine → homogentisate →→→ fumarate

38

Propionic Acidemia

Propionic acid buildup due to propionyl CoA carboxylase deficiency which converts it to methylmalonyl coA
- Val, Ile, Met, Thr
- Odd chain FA’s
- Cholesterol branches

39

LAC Operon: Lactose binds ____

- Lactose binds repressor preventing it from binding the operon


40

______ converts Pro-carcinogens into Carcinogens

CYP450s (microsomal monooxygenase)

41

LAC Operon: Repressor binds _____

- Repressor binds operon (not promoter)

42

LAC Operon: RNA pol binds _____

- RNA pol binds promoter

43

LAC Operon: cAMP-CAP binds _____

- cAMP-CAP binds upstream of promote

44

LAC Operon: Glucose Present

- If glucose is present, it decreases adenylate cyclase --> decreases cAMP --> decreased expression of lac operon proteins

45

P-Bodies

mRNA is processed in nucleus (introns removed, capped and tailed) and enters cytoplasm where P bodies regulate translation and degradation of mRNA

46

When pH > pKa:

H+ protons dissociate
Eg. At 7.4 pH, pKa 2.2 (COOH would be COO-)

47

When pH

H+ protons bind
Eg. At 7.4 pH, pKa 10.2 (NH2 would be NH3+)

48

Hyperchylomicronemia (I)

- Very high level of chylomicrons (milky)
- May develop pancreatitis due to hypertriglyceridemia due to LPL deficiency

49

Familial Hypercholesterolemia (IIA)

Tendon xanthomas and xanthelasmas (eye-lids)

50

tRNA: D arm and T arm Function

- Close to 90 nucleotides in length of non-coding RNA
- D arm: has dihydrouracils, used to recognize the correct aminacyl tRNA synthetase
- T arm: has a sequence needed for tRNA to bind ribosome

51

Methylmalonyl-CoA to Succinyl-CoA requires ______

B12 only (isomerization reaction)
- defects in this reaction lead to methylmalonic acidemia

52

7-a-hydroxylase

Converts cholesterol into bile acids (decreasing chance of gallstone formation)

53

B-glucoronidase

Released secondary to infection by injured hepatocytes and bacteria → hydrolysis of bilirubin glucoronides → increased unconjugated bilirubin in bile
- Increased risk of Brown pigment gallstones

54

PABA

Folic acid precursor in prokaryotes; Huamns cannot convert it to folic acid, so need dietary folic acid

55

Pyruvate Dehydrogenase & a-Ketoglutarate Dehydrogenase Require Co-factors:

B 1, 2, 3, 5 and lipoic acid
- Lipoic acid inhibited by arsenic

56

Biotin (B7) required for:

- Pyruvate to OAA
- Acetyl CoA to Malonyl CoA
- Propionyl CoA to Methylmalonyl CoA

57

ETC Complex Inhibitors

Complex 1: Rotenone
Complex III: Antimycin A
Complex IV: CO, Cyanide
Complex V (ATP synthase): Oligomycin

58

Neonatal E. Coli Sepsis with ______

Classic Galactosemia

59

Urea Cycle: 3 Types

- Carbamoyl Phosphate synthetase 1
- N-acetylglutamate cofactor
- Ornithine Transcarbamylase

60

Homocystinuria: 3 Types

- Cystathionine synthase deficiency
- Decreased affinity for PLP (B6)
- Homocysteine methyltransferase deficiency

61

Cystinuria

- Hereditary defect in amino acid transporter
- Cysteine, Ornithine, Lysine, Arginine (COLA)
- Cysteine stones (hexagonal)

62

Niacin (NAD+) can be synthesized endogenously from _______

Tryptophan

63

Vit A Overdose

- Intracranial edema
- Skin changes
- Hepatosplenomegaly - It is also a teratogen

64

Cells that cannot use Ketone Bodies

RBC’s: lack mitochondria
Hepatocytes: lack succinyl Coa acetoacetate CoA transferase (thiopherase)

65

Refsum Disease

Defect in peroxisomal alpha oxidation → neurologic disturbances due to phytanic acid accumulation
- Treat by avoiding chlorophyll in diet

66

Peroxisomes break down ________

Very long chain fatty acids & fatty acids w/ branch points at odd number carbons that cannot undergo beta oxidation in mitochondria

67

Glycerol Kinase

- Liver specific enzyme
- Glycerol is phosphorylated by G3P
- Only the liver can use glycerol produced by triglyceride degradation via hormone sensitive lipase

68

Detect a Reducing Sugar w/ _______

Copper reduction test (eg. for fructose)

69

Homeobox genes

Code for transcription regulators (role in morphogenesis)

70

Hyperammonemia depletes:

- A-ketoglutarate: causing inhibition of Krebs cycle
- Glutamate: causing glutamine accumulation → astrocyte swelling/dysfunction

71

DNA laddering

Due to apoptosis: DNA fragments appearing in multiples of 180 bp due to cleavage by endonucleases

72

Palmitoylation

Increases protein hydrophobicity by anchoring receptor carboxyl tails to the plasma membrane

73

Beta oxidation

First step is done by acetyl coa dehydrogenase
- Done in states of starvation
- Impaired if hypoglycemia is seen with low ketones

74

Allelic Heterogeneity

Different mutations in the same locus cause similar phenotypes

75

Prader Willi

Father deleted, mother silenced

76

Angelman

Mother deleted, father silenced

77

Cellular differentiation is determined by _________

Transcription factors

78

Gaucher

Glucocerebrosidase deficiency, wrinkled tissue paper cells
- Bone pain, thrombocytopenia, anemia, hepatosplenomegaly, etc.

79

Transformation

Naked DNA from environment

80

Transduction (specialized or general):

Via a bacteriophage

81

Mutations in HOXA-13

Hand, foot, genital (HFG) syndrome

82

Amanita

(in mushrooms) inhibits RNA pol II (which stops production of mRNA)

83

CFTR Mutation

3 bp deletion, degraded post-translationally

84

BH4 (tetrahydrobiopterin) cofactor needed for:

Synthesis of phenylalanine into tyrosine, DOPA, serotonin, and NO

85

Amino acid that makes NO

Arginine

86

Amino acid that makes NH3/Urea

Aspartate

87

Recombination vs Phenotype Mixing vs Reassortment

- Recombination: exchange of genes between 2 chromosomes, progeny will have traits from both parent viruses
- Phenotypic mixing: coinfection, nucleocapsid proteins from one strain on another (w/ original genetic material), not passed to progeny
- Reassortment: Viruses mixing segmented genomes

88

TNF-a and Insulin

Cytokine that induces insulin resistance through phosphorylation of tyrosine kinases

89

Deficiency of Arginase

Buildup of Arginine may be due to deficiency of arginase which is needed to make urea

90

Arginine

- Used alone to make NO
- Also in cycle for Urea

91

NADH and Glucose in setting of Alcohol

NADH High
Glucose Low

92

Fabry Disease

- a-galactosidase A deficiency
- Peripheral neuropathy, angiokeratomas on lower abdomen, and cardio/renal disease
- ceramide trihexoside buildup
- X-linked recessive

93

Lead Poisoning

Colicky abdominal pain, Bluish line on gums (lead line), wrist or foot drop, microcytic anemia w/ basophilic stippling

94

Repressor binds _______

the operator

95

Kozak sequence mutation

- Aw/ thalassemia intermedia (beta globin gene mutation)
- Plays a role in initiation of translation
- mutation that is upstream of the AUG start codon will interfere with mRNA binding to ribosomes

96

_____ required to keep glycolysis (anaerobic metabolism) going

NAD+
replenished by conversion of pyruvate to lactate

97

Segments of alpha helices with many hydrophobic amino acids

Usually transmembrane (membrane spanning) protein

98

Orotic Acid in Urine

Either:
- Urea Cycle problem: Ornithine Transcarbamylase (the carbamoyl phosphate gets converted to orotic acid)
- Pyrimidine Pathway problem: megaloblastic anemia

99

Kernicterus

Unconjudated (water insoluble) bilirubin cannot be excreted so it deposits in the brain
- aw/ crigler-najjar

100

Organophosphates

Irreversible Cholinesterase Inhibitors
Tx: pralidoxime which reactivates cholinesterase and atropine

101

16S rRNA in Prokaryotes

Part of the 30s ribosomal subunit
- contains a sequence complementary to the Shine Delgarno Sequence on the mRNA
- binding is necessary of initiation of protein translation

102

PNMT

Induced by cortisol to convert NE to E

103

Steps of Base Excision Repair

Glycosylase (recognizes abnormal base), Endonuclease (cleaves), Lyase (extracts), Polymerase (fills), Ligase (seals)

104

Squamous metaplasia of specialiszed epithelia to a keratinizing epithelium

Vitamin A deficiency
eg. in someone w/ cystic fibrosis, may see squamous metaplasia of pancreatic exocrine ducts

105

Primers to make complementary DNA

DNA pol only synthesizes in 5-3' direction
and complementary DNA runs antiparallel

106

McArdle Disease

Muscle pain and weakness w/ decreased exercise tolerance
Myophosphorylase deficiency (needed for glycogenolysis)
No hepatomegaly

107

CAAT and TATA boxes

Promoters of transcription in eukaryotic cells (located upstream form transcription start size)

108

Step in Cycle where Urea is Made

Arginine to Ornithine (releases Urea)

109

7 alpha-helical transmembrane proteins

typically G protein coupled receptors (GPCR)
composed of hydrophobic amino acids

110

Non-polar/Hydrophobic amino acids

Glycine, Alanine, Valine, Leucine, Isoleucine, Phenylalanine, Tryptophan, Methionine, and Proline

111

Bloom Syndrome

Photosensitivity, short stature, erythema, and telangectasias
- defect in DNA helicase gene RecQL3
- predisposed to lymphoproliferative and GI malignancies

112

RFLP Procedure

Identifies presence of disease causing mutations or identifies people based on normal variation in genome by restriction site cleaving
- SNPs are the more common cause of a RFLP

113

Defective Proline Hydroxylation during Collagen Synthesis

Leads to failure of Triple Helix formation and stabilization by pro-alpha chains during collagen synthesis

114

MCAD defciency

AR, inability to degrade medium length fatty acids by beta oxidation
- hypoketotic hypoglycemia and neurologic and hepatic dysfunction after fasting or increased metabolic stress
- Heterozygotes have decreased MCAD activity but phenotypically normal

115

Short 30 amino acid alpha helical protein fragment w/ leucin residues at every 7th position

Most likely part of a leucine zipper dimerization
Allows for binding to DNA

116

CPSII (Carbamoyl Phosphate synthase II)

Catalyzes initial step in pyrimidine synthesis
- located in cytosol

117

MODY (Maturity Onset Diabetes of the Young)

- Mutation in glucokinase that decreases its affinity for glucose
- glucokinase is a glucose sensing device in pancreatic beta cells (needs a high concentration of glucose to be activated)

118

Von Gierke Disease

- Deficiency of Glucose 6 phosphatase (glycogen storage disease) --> impaired release of free glucose generated from glycogenolysis and gluconeogenesis
Hepatomegaly and steatosis
Fasting hypoglycemia and lactic acidosis
Hyperuricemia and hyperlipidemia

119

Cori Disease

Defciency of debranching enzyme (glycogen storage disease)
- hypoglycemia, hepatomegaly, muscle weakness
- lots of limit dextrins

120

Pompe Disease

- deficiency of lysosomal enzyme alpha 1,4 glucosidase (acid maltase) [glycogen storage disease]
- Severe cardiomegaly
- Glycogen accumulation in lysosomes

121

Alkaptonuria

AR defect in homogentisic acid oxidase
- can't break down phenylalanine or tyrosine and build up homogentisic acid
- urine turns black with standing, HGA deposits in cartilage, sclera, and dermia (black blue color)
- longstanding disease --> develop ochronosis (darkening of tendons) and arthropathy; brown sclera

122

Malonyl CoA Buildup

Malonyl-CoA inhibits the rate-limiting step in the beta oxidation of fatty acid
- resting muscle requires less energy (and thus less need for fatty acid breakdown) than active muscle

123

Congenital Intolerance to Breast Milk

- galactosemia, in which the body cannot convert galactose to glucose
(resulting in an accumulation of Galactose 1-phosphate)
Lactose (the disaccharide in milk) is composed of glucose + galactose

124

Niacin (B3) Made From:

Tryptophan and requires B2 and B6

125

Galactosyl B-1,4-glucose

Lactose
(its breakdown to glucose and galactose by Lactase in low in lactase deficiency)

126

Conversion of Pyruvate to Lactate

Serves to re-oxidize NADH into NAD in the absence of oxygen in order to keep doing Glycolysis (since it cannot do Krebs without O2)

127

Rb Hyperphosphorylation

Rb is inactivated so cell can transition from G1 to S phase and start proliferating

128

Arsenic Inhibits:

Lipoid Acid which is needed as a cofactors for Pyruvate dehydrogenase (to enter TCA) and also alpha ketoglutarate dehydrogenase
- garlic breath, rice water stool, And vomiting

129

Pyruvate shunted to alanine and lactate in:

Pyruvate dehydrogenase deficiency
- can't do TCA, Neuro defects, lactic acidosis, and high serum alanine
- need to have a ketogenic diet (lysine, leucine)

130

Euglycemia during fasting maintained by: 3 organs

Primarily liver, but also kidney and intestinal epithelium

131

VLDL

TGs to periphery

132

IDL

TGs to Liver

133

LDL

Cholesterol to periphery

134

HDL

Cholesterol to liver

135

Type I hyperchylomicronemia Defect

ApoCII mutation or LPL deficiency

136

Type IIA familial hypercholesterolemia

LDLR deficiency

137

Type IV Hypertriglyceridemia

VLDL overproduction