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Elliot Step 1 > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

Histones are rich in which amino acids?

A

Lysine and arginine

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2
Q

How does MMR enzyme distinguish between old and new strands?

A

DNA methylates cystosine and adenine

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3
Q

Cytosine becomes uracil via?

A

deamination

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4
Q

Guanine has a ?

A

ketone

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5
Q

Thymine has a?

A

Methyl

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6
Q

AA necessary for purine synthesis?

A

GAG; glycine; aspartate; and glutamine

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7
Q

Blocks de novo purine synthesis?

A

6MP (blocks conversion of PRPP to IMP)

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8
Q

IMP comes from?

A

PRPP

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9
Q

Involved in pyrimidine synthesis and urea cycle?

A

Carbamoyl phophate

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10
Q

Deficiency in key enzyme in urea cycle leads to?

A

Ornithine transcarbamoylase def. leads to accumulation of carbamoyl phophate–>orotic acid–>UMP

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11
Q

Blocks ribonucleotide reductase

A

Hydroxyurea (blocks conversion of UDP to dUDP) i.e. blocks doexygenation step

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12
Q

Inhibits Thymidylate synthase

A

5-F,U (Thymydilate synthase usually converts dUMP to dTMP)

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13
Q

5- F, U MOA?

A

blocks thymidylate synthase which converts dUTP to dTMP

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14
Q

Megaloblastic anemia that does not improve with B12 vitamin or folic acid, failure to thrive.

A

Orotic aciduria– inability to convert orotic acid to UMP dt defect in UMP synthase

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15
Q

Defect in UMP synthase leads to?

A

Orotic aciduria– megaloblastic anemia that cannot be fixed with B12 or folic acid, failure to thrive, inc orotic acid in urine

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16
Q

Hyperammonemia; orotic acid in urine– treatment?

A

OTC deficiency– treat with uridine

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17
Q

Adenosine goes to blank via ADA?

A

Inosine–>hypoxanthine

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18
Q

Catalyzes Hypoxanthine to IMP (Inosinic acid)

A

HGPRT +PRPP

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19
Q

Patient presents with self mutiliation, aggression, hyperuricemia, gout– what else might we see on exam?

A

Choreoathetosis– patient has Lesch Nyhan Syndrome–>excess uric acid production

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20
Q

Lesch Nyhan genetics?

A

Xlinked recessive

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21
Q

Two amino acids encoded by only 1 codon?

A

Methionine and tryptophan

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22
Q

Primase?

A

Makes RNA primer on which DNA pol III can initiate replication

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23
Q

Makes RNA primer for DNA pol III to initiate replication?

A

Primase

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24
Q

Proofreads with 3’ to 5’ exonuclease?

A

DNA Pol III

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25
Q

Degrades RNA primer and replaces it with DNA?

A

DNA Pol I– also has 5’ to 3’ exonuclease activity

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26
Q

DNA Pol I

A

degrades RNA primer and replaces it with DNA

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27
Q

DNA ligase functio?

A

Catalyzes the formation of phosphodiesterase bond within a strand of double stranded DNA

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28
Q

Telomerase functin”?

A

Add DNA to 3’ end of chromosomes to avoid loss of genetic material with every duplication

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29
Q

Defect in nucleotide excision repair leads to

A

Xeroderma Pigmentosum– prevents repair of pyrimidine dimers–>squamous cell carcinoma

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30
Q

NER repairs?

A

bulky helix distorting lesions

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31
Q

Glycosylase that recognizes and removes damaged bases?

A

Base excision repair

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32
Q

HNPCC?

A

Mutated mismatch repair gene

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33
Q

Patient presents with dilated blood vessels and history of recurrent falls as he waks?

A

Ataxia telangiectasia– defect in ATM gene; nonhomologous end joining

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34
Q

Zidovudine MOA?

A

AZT; blocks 3’ OH group

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35
Q

Patient develops hepatic necoris after eating a mushroom– what does toxin in mushroom block?

A

Alpha amanitin, found in Amanita phalloides inhibits RNA Pol II

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36
Q

Processing of RNA occurs where?

A

Nucleus (5 prime cap with addition of 7 methylguanosine; polyadenylation on 3’ end; splicing out introns)

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37
Q

Capped, tailed, and spliced mRNA transcript is called?

A

mRNA

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38
Q

Where is 5’ capping of RNA not seen?

A

Mitochondrial genes

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39
Q

Introns?

A

Stay in nuclues; while exons obviously exit nucleus

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40
Q

Common disease caused by alternative splicing?

A

Beta thalaseemia

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41
Q

Job of aminoacyl trna?

A

Scurtinize amino acid before and after it binds to trna– bond is hydrolyzed if pairing is incorrect

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42
Q

Where does tetracycline bind?

A

30S subunit– preventing attachment of aminoacyl-tRNA

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43
Q

Activation of protein synthesis requires?

A

GTP hydrolysis

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44
Q

ATP and tRNA?

A

needed for Activation (ATP for Activation)

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45
Q

GTP and tRNA?

A

Needed for initiation– hydrolyzed

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46
Q

rRNA job?

A

Ribozyme– catalyzes peptide bond formation, trasnfers growing polypeptide to amino acid in A site

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47
Q

Termination of tRNA?

A

Stop codon is recognized by release facotr and protein is released

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48
Q

APE sites on ribosome?

A

A=Incoming aminoacyl trna
P= accomadates growing peptide
E= holds empty rna as it exits

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49
Q

Job of aminoglycosides?

A

Bind 30S and inhibit formation of initiation complex and cuase misreading of mrna

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50
Q

Chloramphenicol?

A

Binds 50S and inhibits peptidyl transferase

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51
Q

Macrolides?

A

Prevent release of uncharged trna after it has donated its amino acid i.e. blocks translocation

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52
Q

Secretory proteins are synthesized?

A

RER

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53
Q

These cells are rich in RER?

A

Mucus secreting goblet cells of small intestine and antibody secreting plasma cells

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54
Q

RER in neurons?

A

Nissle bodies

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55
Q

What do free ribosomes synthesize?

A

cystosolic and organellar proteins

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56
Q

These cells are rich in SER?

A

Adrenal cortex– duh! synthesize hormones

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57
Q

Patient presents with clouded corneas, restricted joint movements, and hight plasma lysosomal enyzymes?

A

I cell disease– failure to add Mannose 6 phosphate

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58
Q

Job of peroxisome?

A

catabolism of very long fatty acids and amino acids

59
Q

Pt. presents with recurrent pyogenic infections; partial albinism and peripheral neuropathy?

A

Chediak higashi–cannot fuse phagosome to lysosome

60
Q

5 drugs that act on microtubules?

A 
Griseofulvin (antifungal)
Paclitaxel (anti breast cancer)
Vincristine
Colchicine
Mebendazole/thiabendazole
61
Q

Links peripheral 9 doublets of cilia?

A

dynein

62
Q

Pt. presents with bronchiectasis; his PMI is located at the right intercostal space– diagnosis?

A

Kartageners– situs inversus; immotile sperm and recurrent sinusitis

63
Q

First mechanism of Ouabain?

A

Inhibits K+– acts like cardiac glycoside

64
Q

Type 1 collagen makes?

A

Bone, skin, tendon, dentin, fascia, cornea, late wound repair

65
Q

Type 2 collagen?

A

CarTWOlage; vitreous body, nucleus pulposus

66
Q

Type 3 collagen?

A

Reticulin– skin, blood vessels, uterus, fetal tissue, granulation tissue

67
Q

Blood vessel– type of collagen?

A

3

68
Q

uterus type of collagen?

A

3

69
Q

vitreous body type of collagen?

A

2

70
Q

nucleus pulposus type of collagen?

A

2

71
Q

Fascia– type of collagen?

A

1

72
Q

cornea type of collagen?

A

1

73
Q

Synthesis, hydroxylation and glycosylation of collagen takes place in?

A

ER

74
Q

Hydroxylation of collagen requires?

A

Vitamin C

75
Q

Problem forming triple helix of collagen chain?

A

osteogenesis imperfecta

76
Q

What happens when collagen leaves fibroblast?

A

Disulfide rich termiahl regions of procollagen are cleaved–>insoluble tropocollagen

77
Q

Enzyme responsible for cross linking collagen?

A

Cu2+ containing lysl oxidase

78
Q

Pt presents with multiple fractures, hearing loss, and problems with his teeth?

A

Type 1 collagen defect– problems with glycosylation– also causes blue sclera due to translucency of connective tissue over choroidal v3eins

79
Q

Elastine is rich in?

A

Proline and GLYcine

80
Q

Wrinkles of aging are due to?

A

Reduced collagen and elastin production

81
Q

What is southwestern blot?

A

Identifies DNA binding proteins

82
Q

Not all individuals with mutatnt genotype show the mutant phenotype?

A

Incomplete pentrance

83
Q

One gene contributes to multiple phenotypic effects?

A

Pleiotropy

84
Q

Tendancy of certain alleles at 2 linked loci to occur together more often than expected to occur

A

Linkage disequilibrium

85
Q

Mutations in different loci can produce the same phenotype?

A

Locus heterogeneity (marfans, homocysteinuria, MEN2B)

86
Q

Prsence of both normal and mutated mtDNA?

A

Heteroplasmy– results in variable expression in mitochondrial inherited disease

87
Q

Boy presents with mental retardation, hyperphagia, obesity, and hypogonadism?

A

Prader willi

88
Q

Boy presents laughter, seizures, and ataxia?

A

Angelmans

89
Q

Genetics of hypophophatemic rickets?

A

X linked dominant– increased phosphate wasting at proximal tubule

90
Q

These diseases often present with myopathy and CNS disease?

A

Mitochondreal myopathies– RAGGED red fibers

91
Q

Pt presents with dwafism– this disease is associated with?

A

Advanced paternal age- Achondroplasia– autosomal dominant

92
Q

Pt presents with flank pain, hematuria, and progressive kidney failure. What chromosome is disease on? Complications?

A

16— APKD– complications include mitral valve prolapse and berry aneurysms

93
Q

Colon becomes covered with adematous polyps after puberty? Chom?

A

5– FAP – five letters in polyp

94
Q

Red dots on lips; recurrent epistaxis, skin discolorations and AVM?

A

Hereditary hermorrhagic telangiectasia

95
Q

sphere shaped blood vessels– defect? Histology?

A

In spectrin or ankrin– cells LACK CENTRAL PALLOR

Splenectomy is curative

96
Q

Caudate atrophy? Decreased levels of? Chrom?

A

Huntingtons– decreased levels of GABA and ACh

Located on chrom 4

97
Q

Pectus excavatum, hypermobile joints, long fingers? Defect?

A

Marfans– defect in fibrillin–> cystic medial necrosis of aorta–>dissecting aneurysm; floppy mitral valve; lens subluxation

98
Q

Lens subluxation +tall?

A

Marfans– pectus excavatumj

99
Q

Blotchy spots on skin; pigmented iris hamartomas? Chrom?

A

Neurofibramotosis type 1– chromosome 17

100
Q

Bilateral acoustic schannomas? Chrom? What else do children have?

A

Neurofib 2 on chrom 22; children also have juvenile cataracts

101
Q

Hypopigmented skin, seizures, renal cysts, and rhabdomyomas?

A

Tuberous sclerosis– see retinal hamartomas and increased incidence of astrocytomas– incomplete penetrance

102
Q

AD disease that leads to increased risk for astrocytoma?

A

Tuberous sclerosis

103
Q

Bilateral renal cell carcinoma and other tumors? Chrom?

A

Von hippel Lindau is on chromosome 3– results in constitutive expression of HIF and activation of angiogenic growth factor

104
Q

X- linked recessive diseases

A

Be Wise, Fool’s GOLD Heeds Silly HOpe:
Brutons, Wiskott, Fabrys, G6PD, Ocular albinism, Lesch, Duchenees ( and bekers), Hunters Syndrome, Hemphilia, Orthinine transcarbamoylase

105
Q

Duchennes is a blank mutation?

A

Frameshift–>deletion of dystrophin; may have cardiac myopathy

106
Q

Trinucleotide repeat inMyotonic dystrophy and Friedreichs?

A

Myotonic=CTG

Friedreichs=GAA

107
Q

Predisposition to mitral valve prolapse? 3

A

PCKD; Fragile X; Marfans

108
Q

Predisposition to Berry aneurysms? 3

A

PCKD; Ehlers Danlos; marfans

109
Q

Prominent epicanthal folds, simian crease, duodenal atresia, gap between 1st two toes– associated with waht type of heart defect?

A

Down syndrome– ostium primum type ASD

110
Q

Quad screen tests that are increased in Down syndrome?

A

Inhibin a and Beta hcg

111
Q

Micrognathia, mental retardation, low set ears clenched hands– chromosome?

A

Edwards

112
Q

Microphthalmia, cleft lip, holo prosencephaly (failure to develop into two hemispheres)

A

Pataus syndrome on chromosome 13– Puberty at 13

113
Q

What is robertson translocation?

A

When long arms of 2 acrocentric chromosomes (chrom with centromeres near their ends) fuse at the centromere and the 2 short arms are lost

114
Q

Cri du chat syndrome– chromosome?

A

VSD– short arm of chromosome 5

115
Q

Extreme friendliness with strangers? chromosome?

A

Williams syndrome– long arm of chromosome 7

116
Q

polyneuritis, symmetrical muscle wasting; vitamin defi

A

b1– dry berberi

117
Q

Baby born with cleft palate; mom says she used acne cream

A

Vit Aexcess

118
Q

Vitamin deficiency causing adrenal insuffiency

A

B5

119
Q

HbC

A

glutamate to lysine

120
Q

accumulated ceramide trihexoside

A

Fabry– peripheral neuropathy, angiokeratoma

121
Q

idruonate sulfatase

A

hunters – no alpha no corneal clouding

122
Q

RLS of urea cycle

A

carbamoyl phosphate synthetase I

123
Q

increases insulin does what to camp

A

Decreases camp–>dec protein kinase A–>dec FBP, Inc PFK2, more glycolysis

124
Q

Neurologic defects in infancy; lactic acidosis

A

pyruvate dehydrogenase– can’t make acetyl coa

125
Q

Blocks complex 1, 3,4,5 in etc

A

Rotenone 1
antimycin 3
CO,cyanide=4
Oligomycin=5– atp synthase inhibitor

126
Q

Infantile cataracts; galactose in urine; cannot develop social smile

A

galactokinase deficiency

127
Q

jaundice, hepatomegaly, infantile cataracts–

A

Classic galactosemia– excluse galactose and LACTOSE

128
Q

Hyperammonemia depletes?

A

excess NH4+ which depletes alpha ketoglutarate leading to inhibition of TCA cycle

129
Q

Glycine

A

porphyrin

130
Q

arginine–>

A

creatinie, urea, NO

131
Q

tryptophan–>

A

niacin via B6 and

Serotonin via BH4

132
Q

lens subluxation; retarded, osteoporosis; tall stature kyphosis; atheroscleorisis

A

homocystinuria– cystathionine syntahse defiency

133
Q

AA in urine

A

cystinuria- COLA– alkanalize urine

134
Q

tryptophan in urine?

A

hartnup–>pellagra because tryptophan makes niacin

135
Q

cardiomegaly, pompes disease

A

lysosomal alpha 1,4, glucosidase

136
Q

deficiency of….. in maple syrup urine disease

A

alpha ketoacid (b1)

137
Q

Pt. presents with diarrhea, dermatitis, dementia; urine shows aminoa acids

A

Hartnups disease– tryptophan excretion in urine and dec absorption from the gut

138
Q

central and peripheral demyelination with ataxia, dementia

A

Metachromatic leukodystrophy— arylsulfatase A deficiency and cerebroside sulftate accumulation

139
Q

Arylsulfatase deficiency?

A

metachromatic leukodystrophy– see accumulation of cerebroside sulfate

140
Q

peripheral neuropathy, optic atrophy, globoid cell

A

Krabbe’s disease– galactocerebrosidase

141
Q

apo b48

A

mediates chylomicron secretion

142
Q

b100

A

binds ldl receptor

143
Q

CII

A

lipoprotein lipase

144
Q

glucose 6 phosphatase is found in the

A

ER

Elliot Step 1 (32 decks)

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