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STEP 1 > Biochem. > Flashcards

Biochem. Flashcards

1
Q

histones are rich in

A

arginine and lysine

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2
Q

histones are what charge

A

positive because DNA is negative

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3
Q

what makes up histone core

A

H2A, H2B, HC AND H4 X2

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4
Q

histones are created in what cell cycle phase

A

S phase

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5
Q

what nucleotides are methylated in DNA methylation

A

cytosine and adenine

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6
Q

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

A

DNA methylation

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7
Q

deamination of cytosine makes?

A

uracil

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8
Q

what nucleotide has a methyl

A

thymine

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9
Q

3 amino acids required for purine synthesis

A

glycine, aspartate, glutamine

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10
Q

most important difference between purine and pyrimadine synthesis?

A

pyrimadine synthesis requires ATP

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11
Q

What enzyme is deficient in orotic aciduria?

A

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

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12
Q

Lefluonamide inhibits what enzyme

A

dihydroorotate dehydrogenase

carbamoyl phosphate —> orotic acid

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13
Q

hydroxyurea inhibits what enzyme

A

ribonucleotide reductase

UDP –> dUDP

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14
Q

5 FU inhibits what enzyme

A

thymidylate snythase

dUMP to dTMP

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15
Q

what three drugs inhibit dihydrofolate reductase and in what organisms?

A

MTX –> humans
TMP –> bacteria
pyrimethamine –> protozoa

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16
Q

rate limiting step for pyrimadine synthesis

A

carbamoyl phosphate synthetase 2

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17
Q

what drugs inhibit IMP dehydrogenase?

A

ribavirin and mycophenolate

IMP –> GMP

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18
Q

what drug (s) inhibit PRPP amidotransferase

A 
6 MP (azathioprine)
PRPP--> IMP
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19
Q

adenosine deaminase deficiency

A

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

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20
Q

lesch nyhan syndrome inheritance

A

x linked recessive

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21
Q

lesch nyhan syndrome pathogenesis

A

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

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22
Q

telomerase adds genetic material to what end of the chromosome?

A

3’ (always start at 5’)

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23
Q

sickle cell mutation

A

glutamic acid to valine

conservative missense

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24
Q

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

A

conservative

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25
Q

duchenne muscular dystrophy is what type of mutation?

A

frameshift

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26
Q

defective in XP?

A

nucleotide excision repair

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27
Q

important in repair of spontaneous / toxic deamination?

A

base excision repair

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28
Q

defective in HNPCC?

A

mismatch repair

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29
Q

mutated in ataxia telangiectasia?

A

nonhomologous end joining

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30
Q

mutated in fanconi anemia

A

nonhomologous end joining

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31
Q

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

A

5’ end of incoming nucleotide = triphosphate

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32
Q

describe how a phosphodiesterase bond is made

A

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

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33
Q

3 stop codons

A

UGA, UAG, UAA

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34
Q

What does alpha amantin do and where is it found?

A

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

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35
Q

Rifampin MOA

A

Inhibits RNA polymerase in prokaryotes

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36
Q

Actinomycin D MOA

A

inhibits RNA polymerase in prokaryotes and eukaryotes

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37
Q

what is hnRNA

A

initially transcribed mRNA (mRNA without the processing)

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38
Q

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

A

anti-spliceosomal RNPS

found in SLE (highly specific!!!)

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39
Q

What are anti-U1 RNA antibodies associated with?

A

mixed connective tissue disease

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40
Q

hsp60 is an example of

A

chaperone protein - involved in facilitating/maintaining protein folding

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

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41
Q

is Rb active when phosphorylated or dephosphorylated

A

dephosphorylated

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42
Q

examples of permanent cells (never go to G0)

A

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

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43
Q

examples of stable (quiescent) cells

A

1) hepatocytes

2) lymphocytes

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44
Q

examples of labile cells

A

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

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45
Q

secretory cells are rich in what organelle?

A

RER

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46
Q

What are Nissl bodies

A

RER in neurons (synthesize neurotransmitters)

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47
Q

DNA methylation where represses transcription

A

CpG islands

48
Q

Rate limiting step of purine synthesis

A

PRPP amidotransferase

49
Q

Where is mRNA synthesized

A

nucleoplasm

50
Q

Where is tRNA synthesized

A

nucleoplasm

51
Q

Where is rRNA synthesized

A

nucleolus

52
Q

5 functions of golgi apparatus

A

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
Q

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

A

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

54
Q

What does a signal recognition particle do

A

cytosolic ribonucleoprotein that traffics proteins from ribosome to RER

55
Q

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

A

buildup of proteins in the cytosol

56
Q

What does a peroxisome break down

A

1) VLCFA
2) BCFA
3) AA

57
Q

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

A

parkinsons!

58
Q

synthesis of what occurs in peroxisomes?

A

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

59
Q

vimentin stains what type of cells

A

connective tissues - sarcoma

60
Q

desmin stains what type of cells

A

muscle - rhabdomyosarcoma or leiomyosarcoma

61
Q

cytokeratin stains what type of cells

A

epithelial cells (keratin) = CA

62
Q

GFAP stains what type of cells

A

neuroglia

seen in glioblastoma

63
Q

neurofilaments stain what type of cells

A

neurons (axon)

neuroblastoma

64
Q

nuclear lamins stain what

A

nuclear envelope and dna within (implicated in progeria)

65
Q

ouabain mOA

A

inhibits NA-K ATPase by binding to K+ site

66
Q

inheritance of OI

A

autosomal dominant

67
Q

OI is from a problem with

A

type I collagen

can’t form the triple helix

68
Q

what part of collagen synthesis requires vitamin C?

A

hydroxylation

69
Q

what part of collagen synthesis requires copper?

A

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

70
Q

ATP7A

A

menkes protein

71
Q

brittle, kinky hair, growth retardation, hypotonia

A

menkes (copper deficiency)

72
Q

difference between elastin and collagen in terms of structure?

A

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

73
Q

what gives elastin its elastic properties

A

cross-linking

74
Q

southern blot detects what?

A

dna probe used to detect DNA

75
Q

northern blot detects what?

A

dna probe to detect rNA

76
Q

western blot detects what?

A

labelled antibody to identify protein sample

77
Q

southwestern blot detects what?

A

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

78
Q

constitutive insertion

A

gene inserted randomly into a genome

79
Q

conditional insertion

A

gene inserted to a target place in a genome

80
Q

mccune albright snydrome is a problem with what?

A

G protein signaling

81
Q

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

A

mccune albright syndrome

82
Q

example of locus heterogeneity

A

albinism

83
Q

example of allelic heterogeneity

A

beta thalassemia

84
Q

using hardy weinberg to calculate x-linked recessive disorders?

A 
males = q
females = q^2
85
Q

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

A

15

86
Q

defects in structural genes are often what type of inheritance?

A

AD

87
Q

enzyme deficiencies are what type of inheritance?

A

autosomal recessive

88
Q

What is hypophosphatemic rickets

A

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

89
Q

gomori trichrome stain

A

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

90
Q

reticulonodular pattern on xray

A

CF

91
Q

cf is what inheritance and found on what chromosome

A

AR, found on chr. 7

92
Q

most common cause of death in duchenne muscular dystrophy

A

dilated cardiomyopathy

93
Q

pathogenesis of myotonic dystrophy

A

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
Q

fragile x pathogenesis

A

CGG trinucleotide expansion in the FMR1 gene on X chromosome

X-tra large testes, jaw, ears

95
Q

CGG repeats

A

fragile X

96
Q

GAA repeats

A

Friedrich ataxia

97
Q

CAG repeats

A

huntington

98
Q

CTG repeats

A

myotonic dystrophy

99
Q

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

A

trisomy 21

100
Q

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

A

trisomy 18 (edwards)

101
Q

low beta-hCG, low PAPPA, high nuchal translucency

A

Patau trisomy 13 (downs has high beta-HCG)

102
Q

clenched hands with overlapping fingers

A

edwards (trisomy 18)

103
Q

clift lip/palate, polydactyly, holoprosencephaly

A

patau (trisomy 13)

104
Q

what chromosomes can undergo robertsonian translocation

A

13 14 15 21 22

105
Q

cri du chat is due to what

A

microdeletion of short arm of chromosome 5 (5p)

106
Q

williams syndrome

A

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

107
Q

von hippel lindau chromosome number

A

3

108
Q

renal cell carcinoma chromosome number

A

3

109
Q

ADPKD with PKD2 defect chromosome number

A

4

110
Q

huntington chromosome

A

4

111
Q

cri du chat chromosome

A

5

112
Q

FAP chromsome

A

5

113
Q

CF chromosome

A

7

114
Q

freidreich ataxia chromosome

A

9

115
Q

wilms tumor chromosome

A

11

116
Q

wilson disease chromosome

A

13

STEP 1 (26 decks)

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