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Flashcards in Biochem. Deck (116):
1

histones are rich in

arginine and lysine

2

histones are what charge

positive because DNA is negative

3

what makes up histone core

H2A, H2B, HC AND H4 X2

4

histones are created in what cell cycle phase

S phase

5

what nucleotides are methylated in DNA methylation

cytosine and adenine

6

how do mismatch repair enzymes distinguish between old and new strands in prokaryotes?

DNA methylation

7

deamination of cytosine makes?

uracil

8

what nucleotide has a methyl

thymine

9

3 amino acids required for purine synthesis

glycine, aspartate, glutamine

10

most important difference between purine and pyrimadine synthesis?

pyrimadine synthesis requires ATP

11

What enzyme is deficient in orotic aciduria?

UMP synthase - decreases conversion of orotic acid to UMP (thus orotic acid builds up --> orotic aciduria)

12

Lefluonamide inhibits what enzyme

dihydroorotate dehydrogenase
carbamoyl phosphate ---> orotic acid

13

hydroxyurea inhibits what enzyme

ribonucleotide reductase
UDP --> dUDP

14

5 FU inhibits what enzyme

thymidylate snythase
dUMP to dTMP

15

what three drugs inhibit dihydrofolate reductase and in what organisms?

MTX --> humans
TMP --> bacteria
pyrimethamine --> protozoa

16

rate limiting step for pyrimadine synthesis

carbamoyl phosphate synthetase 2

17

what drugs inhibit IMP dehydrogenase?

ribavirin and mycophenolate
IMP --> GMP

18

what drug (s) inhibit PRPP amidotransferase

6 MP (azathioprine)
PRPP--> IMP

19

adenosine deaminase deficiency

buildup of ATP and dATP causes feedback inhibition of ribonucleotide reductase - slows DNA synthesis - decreased synthesis of lymphocytes - SCID

20

lesch nyhan syndrome inheritance

x linked recessive

21

lesch nyhan syndrome pathogenesis

HGPRT deficiency - no recycling of purines - everything is converted into uric acid and increased de novo purine synthesis

22

telomerase adds genetic material to what end of the chromosome?

3' (always start at 5')

23

sickle cell mutation

glutamic acid to valine
conservative missense

24

type of missense mutation that results in an amino acid that is similar in chemical structure as the original amino acid

conservative

25

duchenne muscular dystrophy is what type of mutation?

frameshift

26

defective in XP?

nucleotide excision repair

27

important in repair of spontaneous / toxic deamination?

base excision repair

28

defective in HNPCC?

mismatch repair

29

mutated in ataxia telangiectasia?

nonhomologous end joining

30

mutated in fanconi anemia

nonhomologous end joining

31

Where does energy for DNA/RNA synth (phosphodiesterase bonds) come from?

5' end of incoming nucleotide = triphosphate

32

describe how a phosphodiesterase bond is made

3'OH attacks the incoming 5' triphosphate!!!!

33

3 stop codons

UGA, UAG, UAA

34

What does alpha amantin do and where is it found?

inhibits RNA polymerase II (mRNA synth), found in amanita phalloides - death cap mushrooms
causes severe hepatotoxicity if ingested

35

Rifampin MOA

Inhibits RNA polymerase in prokaryotes

36

Actinomycin D MOA

inhibits RNA polymerase in prokaryotes and eukaryotes

37

what is hnRNA

initially transcribed mRNA (mRNA without the processing)

38

what are anti-Smith antibodies and in which disease are they found?

anti-spliceosomal RNPS
found in SLE (highly specific!!!)

39

What are anti-U1 RNA antibodies associated with?

mixed connective tissue disease

40

hsp60 is an example of

chaperone protein - involved in facilitating/maintaining protein folding

hsp60 is expressed at high temps to prevent protein denaturing/misfolding

41

is Rb active when phosphorylated or dephosphorylated

dephosphorylated

42

examples of permanent cells (never go to G0)

1) neurons
2) skeletal and cardiac muscle
3) RBCs

43

examples of stable (quiescent) cells

1) hepatocytes
2) lymphocytes

44

examples of labile cells

1) bone marrow
2) gut epithelium
3) skin
4) hair follicles
5) germ cells

45

secretory cells are rich in what organelle?

RER

46

What are Nissl bodies

RER in neurons (synthesize neurotransmitters)

47

DNA methylation where represses transcription

CpG islands

48

Rate limiting step of purine synthesis

PRPP amidotransferase

49

Where is mRNA synthesized

nucleoplasm

50

Where is tRNA synthesized

nucleoplasm

51

Where is rRNA synthesized

nucleolus

52

5 functions of golgi apparatus

1) glycosylates core proteins to make proteoglycans
2) adds O-oligosaccharide to Serine and Threonine
3) adds N olgiosaccarides to Aspargine
4) adds m6P to lysosomal enzymes
5) adds sulfate to sugars and tyrosine

53

Coarse facial features, clouded corneas, restricted joint movements, high plasma levels of lysosomal enzymes

I cell disease - defect in N-acetylglucosaminyl-1-PHOSPHOTRANSFERASE. No phosphorylation of mannose = low M6P = no targeting of lysosomal enzymes to the lysosome

54

What does a signal recognition particle do

cytosolic ribonucleoprotein that traffics proteins from ribosome to RER

55

What happens if you have absent/deficient signal recognition particle?

buildup of proteins in the cytosol

56

What does a peroxisome break down

1) VLCFA
2) BCFA
3) AA

57

defects in the ubiquitin proteasome system have been implicated in what disease?

parkinsons!

58

synthesis of what occurs in peroxisomes?

plasmalogens - phospholipid found in myelin! No peroxisomes = neurodegenerative disorder.

59

vimentin stains what type of cells

connective tissues - sarcoma

60

desmin stains what type of cells

muscle - rhabdomyosarcoma or leiomyosarcoma

61

cytokeratin stains what type of cells

epithelial cells (keratin) = CA

62

GFAP stains what type of cells

neuroglia
seen in glioblastoma

63

neurofilaments stain what type of cells

neurons (axon)
neuroblastoma

64

nuclear lamins stain what

nuclear envelope and dna within (implicated in progeria)

65

ouabain mOA

inhibits NA-K ATPase by binding to K+ site

66

inheritance of OI

autosomal dominant

67

OI is from a problem with

type I collagen
can't form the triple helix

68

what part of collagen synthesis requires vitamin C?

hydroxylation

69

what part of collagen synthesis requires copper?

lysyl hydroxylase = cross-linking of procollagen (triple helix crosslinking)

70

ATP7A

menkes protein

71

brittle, kinky hair, growth retardation, hypotonia

menkes (copper deficiency)

72

difference between elastin and collagen in terms of structure?

elastin is rich in nonhydroxyylated proline, glycine, and lysine
collagen has hydroxylated proline/glycine/lysine

73

what gives elastin its elastic properties

cross-linking

74

southern blot detects what?

dna probe used to detect DNA

75

northern blot detects what?

dna probe to detect rNA

76

western blot detects what?

labelled antibody to identify protein sample

77

southwestern blot detects what?

oligonucleotide probe to detect DNA binding proteins (like transcription factors)

78

constitutive insertion

gene inserted randomly into a genome

79

conditional insertion

gene inserted to a target place in a genome

80

mccune albright snydrome is a problem with what?

G protein signaling

81

unilateral cafe au lait spots
polyostotic fibrous dysplasia
precocious puberty
endocrine abnormalities

mccune albright syndrome

82

example of locus heterogeneity

albinism

83

example of allelic heterogeneity

beta thalassemia

84

using hardy weinberg to calculate x-linked recessive disorders?

males = q
females = q^2

85

prader willi and angelmans occur because of mutations and deletions on what chromosome

15

86

defects in structural genes are often what type of inheritance?

AD

87

enzyme deficiencies are what type of inheritance?

autosomal recessive

88

What is hypophosphatemic rickets

X linked dominant disorder where there is phosphate wasting in the PCT - resistant to vit. D. Presents like rickets

89

gomori trichrome stain

used to stain ragged red fibers which are part of the mitochondrial myopathies

90

reticulonodular pattern on xray

CF

91

cf is what inheritance and found on what chromosome

AR, found on chr. 7

92

most common cause of death in duchenne muscular dystrophy

dilated cardiomyopathy

93

pathogenesis of myotonic dystrophy

CTG trinucleotide repeat in the DMPK gene - abnormal expression of myotonin protein kinase - causes myotonia, muscle wasting, cataracts, testicular atrophy, balding, arryhtmia (testicles, toupee, ticker, myoTonia)

94

fragile x pathogenesis

CGG trinucleotide expansion in the FMR1 gene on X chromosome
X-tra large testes, jaw, ears

95

CGG repeats

fragile X

96

GAA repeats

Friedrich ataxia

97

CAG repeats

huntington

98

CTG repeats

myotonic dystrophy

99

low AFP, high beta-HCG, low estriol, high inhibin A

trisomy 21

100

low ATP, low beta-HCG, low estriol, low/normal inhibin A

trisomy 18 (edwards)

101

low beta-hCG, low PAPPA, high nuchal translucency

Patau trisomy 13 (downs has high beta-HCG)

102

clenched hands with overlapping fingers

edwards (trisomy 18)

103

clift lip/palate, polydactyly, holoprosencephaly

patau (trisomy 13)

104

what chromosomes can undergo robertsonian translocation

13 14 15 21 22

105

cri du chat is due to what

microdeletion of short arm of chromosome 5 (5p)

106

williams syndrome

deletion of long arm of chr. 7 that contains elastin gene

107

von hippel lindau chromosome number

3

108

renal cell carcinoma chromosome number

3

109

ADPKD with PKD2 defect chromosome number

4

110

huntington chromosome

4

111

cri du chat chromosome

5

112

FAP chromsome

5

113

CF chromosome

7

114

freidreich ataxia chromosome

9

115

wilms tumor chromosome

11

116

wilson disease chromosome

13