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Biochemistry III > Some Test1.pdf Final Past Papers > Flashcards

Some Test1.pdf Final Past Papers Flashcards

1
Q 
Which enzyme is allosterically modulated by malonyl-CoA?
A. Acylcarnitine translocase
B. Carnitine palmitoyl-transferase II
C. Carnitine palmitoyl-transferase I
D. Acyl-CoA synthetase
E. ATP Citrate Lyase
A

C. Carnitine palmitoyl-transferase I

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2
Q

Select the statements valid for the bile acids:
1. In bile acid synthesis, the side chain of cholesterol is oxidized
2. In bile acid synthesis, carbon atoms 7 and 12 are methylated
3. The secondary bile acids are produced from primary bile acids through deconjugation and dehydroxylation at carbon atom 7
4. Glycocholic and taurocholic acid are primary bile acids
5. Lithocholic acid is formed from glycocholic acid by bacteria in the large intestine
A: 1,2,3 B: 1,3,4
C: 1,3,5 D: 2,4,5
E: all of the above

A

B: 1,3,4 (C7 and 12 are hydroxylated, not methylated, and lithocolic acid is derived from chenodeoxycholyl-CoA)

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3
Q

Which statements are true?
1. Cholesterol is formed from HMG-CoA synthesized in the mitochondria
2. Cholesterol is formed from HMG-COA synthesized in the cytosol
3. Mevalonate is formed from HMG-CoA by decarboxylation
4. NADPH is needed for mevalonate synthesis
5. Production of isopentenyl-pyrophosphate also requires a decarboxylase
A: 2,4,5 B: 1,2,3,4,5
C: 2,3,4 D: 2,3,4,5
E: 1,4,5

A

A: 2,4,5
(1: HMG-CoA from the mitochondria is for ketone bodies, not for cholesterol, 3: mevalonate is formed by reducing HMG-CoA, requiring NADPH via HMG-CoA Reductase)

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4
Q

Which of the following is NOT true of the fatty acid elongation system of vertebrate cells?
A: it is located in the smooth endoplasmic reticulum
B: it uses malonyl-CoA as a substrate
C: it produces stearoyl-CoA by the extension of palmitoyl-CoA
D: the immediate precursor of the added carbons is acetyl-CoA
E: it involves the same 4 step sequence seen in the fatty acid synthase complex

A

D: the immediate precursor of the added carbons is acetyl-CoA(correctly, it’s acyl-CoA)

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5
Q

If an aerobic organism (e.g. bacterium E. Coli) were fed each of the following four compounds as a source of energy, the energy yield per mole from these molecules would be, in order:A: glucose > alanine > palmitate (16:0)B: palmitate > alanine > glucoseC: palmitate > glucose > alanineD: glucose > palmitate > alanineE: alanine > glucose > palmitate

A

C: palmitate > glucose > alanine
(my logic is that alanine can be converted to pyruvate, which will miss out on the ATP formation during glycolysis that otherwise occurs with glucose metabolism)

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6
Q

Transport of fatty acids from the cytoplasm to the mitochondrial matrix requires:
A: ATP, coenzyme A, and hexokinase
B: ATP, carnitine, and coenzyme A
C: carnitine, coenzyme A, and hexokinase
D: ATP, carnitine, and pyruvate dehydrogenase
E: ATP, coenzyme A, and pyruvate dehydrogenase

A

B: ATP, carnitine, and coenzyme A

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7
Q

Aminophenazone N-demethylation is catalyzed by:A: cytochrome oxidaseB: catalaseC: a cytochrome P450 isoenzymeD: superoxide dismutaseE: S-adenosyl methionine

A

C: a cytochrome P450 isoenzyme(a CYP monooxygenase)

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8
Q

Activation of protein kinase C1. can be Ca2+ dependent2. can be Ca2+ independent 3 can be induced by diacylglycerol4. can be stimulated by phorbol esthers5. can be phospholipid dependentA: 1,3,4 B: 2,3,4,5C: 1,2,3,4,5 D: 1,5E: 2

A

C: 1,2,3,4,5
(Pretty sure on this, but other person who did this chose A instead. However, Torocsik said that some PKC types that we don’t need to know don’t even need calcium to be active)

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9
Q 
Which factor is NOT involved in the muscle contraction following signal transmission in the neuromuscular junction?
A. Ryanodine receptor
B. Dihydropyridine receptor
C. Nicotinic receptor
D. Beta receptor
E. L-type Ca2+ channel
A

D. Beta receptor(assuming they’re talking about the adrenergic one and not something obscure)

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10
Q 
Which factor is involved in the efflux of Ca2+ from the mitochondria?
A. Ca-uniporter
B. IP3 receptor
C. Na+-Ca2+ exchange
D. T-channel
E. Ryanodine receptor
A

C. Na+-Ca2+ exchange

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11
Q

Which of the following receptors functions as a Ca2+ channel?
A. Nicotinic receptor in the skeletal muscle
B. alpha1 receptor of smooth muscle cells in the blood vessel wall
C. NMDA receptor in the CNS
D. D2 receptor in the striatum
E. muscarinic receptor in the heart

A

C. NMDA receptor in the CNS
(NMDA is permeable to univalent and divalent cations, AMPA is permeable to univalent. D2 is a Gi GPCR, nicotinic receptors are for univalent cations)

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12
Q 
Which Ca2+ channel is rapidly inactivated in the heart?A: L
B: N
C: P
D: T
E: cholinergic nicotinic receptor
A

D: T

not sure why the person who did this before said the L-type was correct…

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13
Q 
Which of the following mechanisms are characteristic for the ER?
1. SERCA
2. PMCA
3. IP3 Receptor
4. Ryanodine receptor
5. Na+-Ca2+ exchanger
A. 1,2,3    B. 1,3,5
C. 2,3,4    D. 1,3,4
E. 3,4,5
A

D. 1,3,4

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14
Q 
Which statements are true for the IP3 receptor?
1. it is localized both in the plasma membrane and the ER
2. it is a calcium channel
3. it has 4 Ca2+ binding sites
4. it binds ATP
5. it is activated by phospholipase C
A: 1,3,5   B: 2,4,5
C: 2,3,4   D: 1,2,3
E: 3,4,5
A

B: 2,4,5

2 and 5 are definitely true, the ATP binding is new to me but no other options…

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15
Q

Which statement is NOT true concerning the ryanodine receptor?
A. It has a Ca2+ channel
B. It has 4 subunits
C. It is the largest ion channel
D. It is regulated by calmodulin
E. The same isoform is present in the heart and skeletal muscle

A

E. The same isoform is present in the heart and skeletal muscle
(skeletal muscle = RYR I, heart = RYR 2)

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16
Q

Which statement is true concerning malignant hyperthermia?
1. it is characterized by rigidity of skeletal muscles
2. it is a consequence of abnormal CNS thermoregulation
3. it is the consequence of the mutation of the ryanodine receptor
4. it can be treated with Ca2+ channel blockers
5. it is accompanied by intensive lactate production in the muscle
A: 1,3,5 B: 2,4,5
C: 1,2,4 D: 3,4,5
E: 1,4,5

A

A: 1,3,5

17
Q

Which of the following conversions requires more than one step?
1. alanine -> pyruvate
2. Glutamate -> alpha ketoglutarate
3. asparate -> oxaloacetate
4. proline -> glutamate
5. phenylalanine -> succinate
A: 1,2,4 B: 1,3,5C: 2,4,5 D: 1,4,E: 4,5

A

E: 4,5

alanine -> pyruvate in the same reactions as both Glu -> alphaKG and Asp -> Oxaloacetate. Transaminase rxns

18
Q

Select the valid statements:
1. S-adenosylmethionine provides methyl-group for the synthesis of epinephrine from norepinephrine
2. S-adenosylmethionine provides methyl-group for the synthesis of phosphatidylcholine from phosphatidylethanolamine
3. S-adenosylmethionine provides methyl-group for the synthesis of dTMP from dUMP
A: 1,2 B: 1,2,3
C: 1 D: 2,3
E: 1,2

A

A: 1,2

19
Q 
Phenylketonuria is a consequence of:
1. dihydrobiopterin reductase
2. vitamin B6 deficiency
3. phenylalanine hydroxylase
4. defective synthesis of biopterin
5. vitamin C deficiency
A: 2,3,4    B: 1,3,4
C: 3,4,5    D: 1,4,5
E: 2,4,5
A

B: 1,3,4
I believe this is correct but just poorly worded. It should say DEFICIENCY of 1 and 3, while 4 is the only one that is worded correctly.

20
Q 
Which of the following agents and enzymes are required for the synthesis of cystein?
1. methionine
2. adenosylhomocysteinase
3. serine
4. cystathione synthase
5. cystathionase
A: all   B: 1,2,3,5
C: 1,3,4,5   D: 3,4,5
E: 1,4,5
A

C: 1,3,4,5

21
Q 
Which enzyme is NOT involved into the heme biosynthesis?
A: heme oxygenase
B: delta-aminolevulinic acid synthase
C: delta-aminolevulinic acid dehydratase
D: urophorphyrinogenase III synthase
E: urophorphyrinogenase III cosynthase
A

A: heme oxygenase
(don’t need to know all those other enzymes if you just know that heme oxygenase is part of breaking down heme, not building it)

22
Q

Glutathione is a(n)
A. product of glutamate and methionine
B. tripeptide of glycine, glutamate, and cysteine
C. enzyme essential in the synthesis of glutamate
D. methyl-group donor in many biosynthetic pathways

A

B. tripeptide of glycine, glutamate, and cysteine

23
Q

Which of the listed interrelations are valid for the following two statements:

  1. The regeneration of S-adenosylmethionine (SAM) does not require energy
  2. Methyl group is directly transferred from methyl H4folate to S-adenosylhomocysteine

A: Statement 1 and 2 are both valid, and 1 is the consequence of 2
B: Neither statement is valid
C: Statements 1 and 2 are both valid, but there is no causative relation between them
D: Statements 1 is valid, but 2 is not
E: Statement 2 is valid, but 1 is not

A

B: Neither statement is valid

ATP is required, and methyl from methyl H4folate is transferred to HomoCys, not S-adenosylhomocysteine

24
Q

What is the consequence of inherited adenosine deaminase deficiency?
A. gout
B. mental retardation with self mutilation
C. immunodeficiency
D. muscle cramps
E. orotic aciduria

A

C. immunodeficiency

25
Q 
DNA in a closed-circular, double-stranded molecule with no net bending of the DNA axis on itself is:
A. supercoiled
B. relaxed
C. underwound
D. a left-hand helix
E. the form found in eukaryotic cells
A

B. relaxed

26
Q

Which of the following concerning regulation of eukaryotic gene expression is NOT correct?
A. most regulation is positive (involves activators, no repressors)
B. transcription and translation are physically separated
C. transcription is associated with major changes in chromosomal organization
D. transcription does not involve promoters
E. one gene can encode various proteins

A

D. transcription does not involve promoters(this is clearly not true, dunno wtf is up with the others)

27
Q

Nucleosomes:
A. are important features of chromosome organization in both eukaryotes and bacteria
B. are composed of proteins rich in acidic amino acids such as Asp and Glu.
C. are composed of protein and RNA
D. bind DNA and alter its supercoiling.
E. occur in chromatin at irregular intervals along the DNA molecule

A

E. occur in chromatin at irregular intervals along the DNA molecule
(not in bacteria. histones have basic amino acids like Lys, Arg and His. no RNA. option “D” refers to topoisomerases.)

28
Q

The oxidative deamination of a cytosine side chain of the DNA
1. May be repaired because uracil is strange in the DNA
2. Can cause a transition from C-G to T-A in a part of the progeny DNA molecules
3. The repair mechanism of this lesion requires the activity of a specific glycosylase
A: 1,2,3 B: 1,2
C: 2,3 D: 1,3
E: 2

A

A: 1,2,3
(Uracil is deaminated cytosine, typical in RNA but not DNA. In daughter strands it binds to thymine, and then that in later strands will bind to adenine. N-glycosylases recognize and remove abnormal bases in base excision repair)

29
Q

In the course of the replication of a complete circular double-stranded prokaryotic DNA molecule
1. The synthesis of one of the new circular chains requires significantly more RNA primers than the other
2. The replication starts at a single site of the parental DNA
3. The replication forks proceed in two directions
A: 2,3 B: 1,2,3
C: 1,2 D: 1
E: 1,3

A

B: 1,2,3

30
Q 
The half life time of mRNA in higher eukaryotes depends upon:
1. the presence or absence of introns
2. the length of the poly-A tail
3. the nonsense-mediated mRNA decay pathway
4. sequences at the 3' UTR
5. the length of the total mRNA
A: 1,2,3,4    B: 1,2,5
C: 2,5      D: 1,3,4
E: 2,4
A

A: 1,2,3,4 (probably but not completely sure, please check for yourself)

31
Q

Compared with DNA polymerase, reverse transcriptase:
A. makes fewer errors in synthesizing a complimentary polynucleotide
B. makes more errors because it lacks the 3’-> 5’ proofreading exonuclease activity
C. introduces no errors into genetic material because it synthesizes RNA, not DNA
D. synthesizes complimentary strands in the opposite direction from 3’-> 5’E. has none of the above characteristics

A

B

32
Q

Which of the following can be considered the most precise modern definition of a gene?
A. a segment of genetic material that determines one trait
B. a segment of genetic material that determines one phenotype
C. a segment of genetic material that codes for one protein
D. a segment of genetic material that codes for one polypeptide
E. a segment of genetic material that codes for one polypeptide or RNA product

A

E. a segment of genetic material that codes for one polypeptide or RNA product

33
Q 
A chromosomal region that is the point of attachment of the mitotic spindle is the:
A. Alu sequence
B. telomere
C. centromere
D. intron
E. exon
A

C. centromere

34
Q

Which of the following statements concerning introns is NOT correct?
A. they are frequently present in eukaryotic genes but rarely in prokaryotic genes
B. they are transcribed but not translated
C. they contain base sequences that code for unusual amino acid sequences in proteins
D. there can be multiple introns within a single gene

A

C. they contain base sequences that code for unusual amino acid sequences in proteins

(introns don’t normally code, although i think there are some exceptions as they have found out more about DNA, but still for our purposes this should be the right answer)

35
Q

The DNA in a bacterial (proykaryotic) chromosome is best described as:
A. a single linear double helical molecule
B. multiple linear double-helical molecules
C. a single circular double helical molecule
D. a a single linear single-stranded molecule
E. multiple linear single-stranded molecules

A

C. a single circular double helical molecule

36
Q

Bacterial plasmids:
A. are always covalently joined to the bacterial chromosome
B. often encode proteins not normally essential to the bacterium’s survival
C. are composed of RNA
D. are never circular
E. cannot replicate when cells divide

A

B. often encode proteins not normally essential to the bacterium’s survival

37
Q

The DNA in a eukaryotic chromosome is best described as:
A. a single linear double-helical molecule
B. multiple linear double-helical molecules
C. a single circular double helical molecule
D. a a single linear single-stranded molecule
E. multiple linear single-stranded molecules

A

A. a single linear double-helical molecule

38
Q

Which of these statements about nucleic acids is FALSE?
A. the genome of many plant viruses is RNA
B. the chromosome of E. coli is a closed-circular, double-helical DNA
C. mitochondria and chloroplasts contain DNA
D. the DNA of viruses is commonly many times longer, in its extended form,, than the virus itself
E. plasmids are genes that encode plasma proteins in mammals

A

E. plasmids are genes that encode plasma proteins in mammals

39
Q

Which of the following statements are true?
1. Glycolysis takes place in all human cells
2. the presence of oxygen is necessary for glycolysis
3. Pasteur effect is the phenomenon by which oxygen indirectly induces glycolysis
4. in mitochondrium containing cells, the end product of glycolysis is pyruvate
5. red blood cells are capable of producing 4 mol of ATP from 1 mol of glucose
A: 1,4 B: 1,2,4
C: 1,3,4 D: 4,5
E: 1,3,4,5

A

A: 1,4

#4 tries to trick you with the mitochondria part, it really doesn’t matter for just glycolysis

Biochemistry III (35 decks)

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