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Step 1 High Yield > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

Dihydroorate dehydrogenase is involved in addition of _______ to _______ and blocked by _________

A

Dihydroorate dehydrogenase is involved in addition of Aspartate to Carbamoyl phosphate and blocked by Leflunomide

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2
Q

What converts dUMP to dTMP and what inhibits this enzyme?

A

Thymidylate synthase

Inhibited by 5-FU

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3
Q

What is the function of HGPRT?

A

Purine salvage - converts hypoxanthine to IMP and guanine to GMP

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4
Q

What happens with a deficiency of HGPRT?

A

Lesch-Nyhan syndrome - results in excess uric acid production and de novo purine synthesis

Hyperuricemia
Gout
Pissed off (self mutilation)
Retardation
dysTonia
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5
Q

What amino acids are necessary for purine synthesis?

A

Glycine
Aspartate
Glutamine

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6
Q

Which amino acids are encoded by only 1 codon?

A

Methionine (AUG) and tryptophan (UGG)

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7
Q

Origin of replication is single in ______ but multiple in ________

A

Origin of replication is single in prokaryotes but multiple in eukaryotes

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8
Q

What is the difference between DNA polymerase I and III?

A

III: Leading strand and lagging strand; 5’ to 3’ synthesis and 3’-5’ proofreading
I: Degrades RNA primer and replaces it with DNA - excises RNA primer with 5’-3’ exonuclease

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9
Q

Duchenne Muscular dystrophy is due to a _______ mutation

Sickle cell disease is due to a ________ mutation

A

Duchenne Muscular dystrophy is due to a frameshift mutation

Sickle cell disease is due to a missense mutation

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10
Q

RNA polymerase I makes _RNA
RNA polymerase II makes _RNA
RNA polymerase III makes _RNA

Which is inhibited by amanita phalloides?

A

1: rRNA
II: mRNA - Inhibited by Amanita Phalloides
III: tRNA

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11
Q

What is responsible for quality control after mRNA is transported out of the nucleus?

A

P-bodies - contain exonucleases, decapping enzymes, and microRNAs

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12
Q

Antibodies to snRNPs are highly specific for ___

A

SLE

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13
Q

What is the function of the following parts of tRNA
T-arm:
D-arm:
3’CCA end:

A

T-arm: necessary for tRNA ribosome binding
D-arm: Necessary for tRNA recognition by correct aminoacyl tRNA synethetase
3’CCA end: Amino acid acceptor site

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14
Q

What catalyzes the binding of amino acid to tRNA?

What happens if it is malfunctioning?

A

Aminoacyl-tRNA synthetase

A mischarged tRNA reads usual codon but inserts wrong amino acid

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15
Q

What are the functions of ATP and GTP in protein synthesis?

A

ATP - tRNA activation

GTP - tRNA gripping and going places - translocation

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16
Q

RER is for protein secretion and addition of _______ to many proteins

Where is RER abundant?

A

N-linked oligosaccharide

RER is abundant in mucus-secreting goblet cells of the small intestine and antibody-secreting plasma cells

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17
Q

SER is the site of steroid synthesis and ________ of _______

Where is it found?

A

Detoxification of drugs and proteins

Liver hepatocytes and steroid hormone producing cells of adrenal cortex and gonads are rich in SER

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18
Q 
What is the function of the following Golgi associated proteins...
Signal recognition particle (SRP):
COPI:
COPII:
Clathrin:
A

Signal recognition particle (SRP): traffics proteins from ribosome to RER
COPI: Golgi to Golgi (retrograde) and Golgi to ER
COPII: Golgie eto Golgi (anterograde) and ER to Golgi
Clathrin: trans-Golgi to lysosomes or plasma membrane to endosomes

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19
Q

What parts of collagen synthesis occur inside fibroblasts?

A

1) Synthesis (Gly-X-Y)
2) Hydroxylation of proline and lysine residues
3) Glycosylation of pro-alpha chain hydroxylysine residues and formation of pro-collagen (hydrogen and disulfide bonds)
4) Exocytosis

20
Q

What parts of collagen synthesis occur outside of fibroblasts?

A

5) Cleavage of disulfide-rich terminal regions of procollagen transforming it into insoluble tropocollagen
6) Reinforcement of staggered tropocollagen molecules by covalent lysine-hydroxylysine cross-linkage to make collagen fibrils

21
Q

Osteogenesis imperfecta is due to a defect in which stage of collagen synthesis?

A

Formation of triple helix

22
Q

Menkes disease is due to impaired absorption and transport of _______

A

copper

23
Q

What is pleiotropy?

A

One gene contributes to multiple phenotypic effects

24
Q

What is heteroplasmy?

A

Presence of both normal and mutated mitochondrial DNA resulting in variable expression in mitochondrial inherited disease

25
Q

Uniparental disomy:
Which type indicates a meiosis I error?
Which type indicates a meiosis II error?

A

Uniparental disomy - offspring receives 2 copies of a chromosome from 1 parent and no copies from the other parent
Heterodisomy/heterozygous indicates a meiosis I error
Isodisomy/homozygous indicates a meiosis II error

26
Q

In Hardy-Weinberg population genetics, the frequency of an x-linked recessive disorder in males = __ and in females = __

A 
Males = q
Females  = q^2
27
Q

What is imprinting?

A

At some loci, only one allele is active; the other is inactive (methylation) - if the active allele is deleted there is disease

28
Q

Prader-Willi and Angelmann syndrome are due to mutation or deletion of genes on chromosome __

A

15

29
Q

What are the features of Prader-Willi syndrome

A 
Hyperphagia
Obesity
Intellectual dysability
Hypogonadism
Hypotonia
30
Q

What are the clinical features of Angelman syndrome?

A

Inappropriate laughter
Seizures
Ataxia
Severe intellectual disability

31
Q

What are the features of hereditary hemorrhagic telangiectasia (AKA Osler-Weber-Rendu syndrome)?

A 
Inherited disorder of blood vessels
Telangiectasia
Recurrent epistaxis
Arteriovenous malformation
GI bleeding
Hematuria
32
Q

What is the normal function of the chloride channel affected by cystic fibrosis?

A

Secretes Cl- in the lungs and GI tract and reabsorbs Cl- in sweat glands

33
Q

What is the consequence of increased intracellular Cl- in cystic fibrosis?

A

Compensatory increase in Na+ reabsorption via epithelial Na+ cells leading to increased H2O reabsorption leading to abnormally thick mucus secreted into lungs and GI tract

*Also increased Na+ reabsorption causes more negative transepithelial potential difference

34
Q

A CTG trinucleotide repeat expansion in the DMPK gene causes __________ which involves an abnormal expression of ________ _________ ________

A

A CTG trinucleotide repeat expansion in the DMPK gene causes Myotonic Type I which involves an abnormal expression of Myotonin protein kinase

35
Q

Fragile X syndrome is due to defect affecting the methylation and expression of the _____ gene

What are the findings?

A

FMR1

Fragile X - eXtra large testes, jaw and ears

36
Q

Cri-du-chat syndrome is a congenital microdeletion of the short arm of chromosome __

A

5

37
Q

Williams syndrome is a congenital microdeletion of the long arm of chromosome __ which includes the ________ gene

A

7; elastin

38
Q

Vitamin A prevents _________ _________ and is used to treat measles and ___ subtype M3

A

Vitamin A prevents squamous metaplasia and is used to treat measles and AML subtype M3

39
Q

What TCA cycle reaction requires FAD as a cofactor?

A

Succinate dehydrogenase reaction

40
Q

How does niacin treat dyslipidemia

A

Lowers levels of VLDL and raises levels of HDL

41
Q

Facial flushing in Vitamin B3 deficiency is induced by ________

A

Prostaglandin

42
Q

What liver products are an example of transamination reactions (which require vitamin B6)?

A

ALT and AST

43
Q

What neurotransmitters require vitamin B6 for synthesis?

A

Serotonin, Epinephrine, Norepinephrine, Dopamine, and GABA

44
Q

What is the function of Vitamin B9 (folate)?

What happens with B9 deficiency?

A

Function: Converted to THF and serves as coenzyme for 1-carbon transfer/methylation reactions
Deficiency: Macrocytic, megaloblastic anemia; hypersegmented neutrophils; glossitis

45
Q

What are the consequences of the increased NADH/NAD ratio in ethanol metabolism?

A

Pyruvate to lactate (lactic acidosis)
Oxaloacetate to malate (prevents gluconeogenesis)
Glyceraldehyde-3-phosphate to glycerol-3-phosphate (which combines with fatty acids to make triglycerides leading to hepatosteatosis)

46
Q

Disulfiram inhibits acetaldehyde dehydrogenase

_________ inhibits alcohol dehydrogenase

A

Fomepizole (for methanol or ethylene glycol poisioning)

47
Q

Name the following types of bacterial genetics…
Ability to take up naked DNA (from cell lysis) from environment:
Segment of DNA (transposon) jumps from one location to another:
Lytic phage infects bacterium→ DNA packaged in viral capsid → gene transfer:

A

Ability to take up naked DNA (from cell lysis) from environment: Transformation
Segment of DNA (transposon) jumps from one location to another: Transposition
Lytic phage infects bacterium→ DNA packaged in viral capsid → gene transfer: Transduction

Step 1 High Yield (21 decks)

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