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Biochemistry > Exam 3 - Exam Questions From Book > Flashcards

Exam 3 - Exam Questions From Book Flashcards

1
Q 
2. Identify the metabolite that does NOT serve as a precursor of a dietarily essential amino acid: 
	A. Alpha-ketoglutarate
	B. 3-phosphoglycerate
	C. Glutamate
	D. Aspartate
	E. Histamine
A

E. Histamine

Histamine is a catabolite, not a precursor, of histidine.

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2
Q 
4. Select the CORRECT answer:
The first reaction in the degradation of most of the protein amino acids involves the participation of:
	A. NAD+
	B. Thiamine pyrophosphate (TPP)
	C. Pyridoxal phosphate
	D. FAD
	E. NAD+ and TPP
A

C. Pyridoxal phosphate

Pyridoxal-dependent transamination is the first reaction in
degradation of all the common amino acids except threonine,
lysine, proline, and hydroxyproline.

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3
Q 
5. Identify the amino acid that is the major contributor to the transport of nitrogen destined for excretion as urea:
	A. Alanine
	B. Glutamine
	C. Glycine
	D. Lysine
	E. Ornithine
A

B. Glutamine

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4
Q
  1. For metabolic disorders of the urea cycle, which statement is NOT CORRECT:
    A. Ammonia intoxication is most severe when the metabolic block in the urea cycle occurs prior to the reaction catalyzed by argininosuccinate synthase
    B. Clinical symptoms include mental retardation and the avoidance of protein-rich foods
    C. Clinical signs can include acidosis
    D. Aspartate provides the second nitrogen of argininosuccinate
    E. Dietary management focuses on a low-protein diet ingested as frequent small meals
A

C. Clinical signs can include acidosis

Due to the failure to incorporate NH4+ into urea, clinical
signs of metabolic disorders of the urea cycle include alkalosis,
not acidosis.

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5
Q
  1. Select one of the following statements that is NOT CORRECT:
    A. One metabolic function of glutamine is to sequester nitrogen in a nontoxic form
    B. Liver glutamate dehydrogenase is allosterically inhibited by ATP and activated by ADP.
    C. Urea is formed both from absorbed ammonia produced by enteric bacteria and from ammonia generated by tissue metabolic activity.
    D. The concerted action of glutamate dehydrogenase and glutamate aminotransferase may be termed transdeamination
    E. Fumarate generated during biosynthesis of argininosuccinate ultimately forms oxaloacetate in reactions in mitochondria catalyzed successively by fumarase and malate dehydrogenase
A

E. Fumarate generated during biosynthesis of argininosuccinate ultimately forms oxaloacetate in reactions in mitochondria catalyzed successively by fumarase and malate dehydrogenase

Cytosolic fumarase and cytosolic malate dehydrogenase
convert fumarase to oxaloacetate following a cytosolic reaction of the urea cycle. The mitochondrial fumarase and malate dehydrogenase function in the TCA cycle, not urea biosynthesis.

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6
Q
  1. Select one of the following statements that is NOT CORRECT:
    A. Threonine provides the thioethanol moiety for biosynthesis of coenzyme A
    B. Histamine arises by decarboxylation of histidine
    C. Ornithine serves as a precursor of both spermine and spermidine
    D. Serotonin and melatonin are metabolites of tryptophan
    E. Glycine, arginine, and methionine each contribute atoms for biosynthesis of creatinine
A

A. Threonine provides the thioethanol moiety for biosynthesis of coenzyme A

Serine, not threonine, provides the thioethanol moiety of coenzyme A.

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7
Q
  1. Select one of the following statements that is NOT CORRECT:
    A. Excreted creatinine is a function of muscle mass, and can be used to determine whether a patient has provided a complete 24-hour urine specimen
    B. Many drugs and drug catabolites are excreted in urine as glycine conjugates.
    C. The major nonprotein metabolic fate of methionine is conversion to S-adenosylmethionine.
    D. The concentration of histamine in brain hypothalamus exhibits a circadian rhythm
    E. Decarboxylation of glutamine forms the inhibitory neurotransmitter GABA
A

E. Decarboxylation of glutamine forms the inhibitory neurotransmitter GABA

Decarboxylation of glutamate, not glutamine forms GABA.

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8
Q 
15. Which of the following is NOT a hemoprotein?
A. Myoglobin	
B. Cytochrome c
C. Catalase
D. Cytochrome P450
E. Albumin
A

E. Albumin

Albumin is not a hemoprotein. In cases of hemolytic anemia, albumin can bind some metheme, but unlike the other proteins listed, albumin is not a hemoprotein.

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9
Q 
16. A 30-year old man presented at a clinic with a history of intermittent abdominal pain and episodes of confusion and psychiatric problems. Laboratory tests revealed increases of urinary Gamma-aminolevulinate and porphobilinogen. Mutational analysis revealed a mutation in the gene for uroporphyrinogen I synthase. The probable diagnosis was:
A. Acute intermitten porphyria	
B. X-linked sideroblastic anemia
C. Congenital erythropoietic porphyria
D. Porphyria cutanea tarda
E. Variegate porphyria
A

A. Acute intermittent porphyria

Acute intermittent porphyria is due to mutations in the gene for uroporphyrin I synthase

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10
Q
  1. Select one of the following statements that is NOT CORRECT:
    A. Bilirubin is a cyclic tetrapyrrole
    B. Albumin-bound bilirubin is transported to the liver
    C. High levels of bilirubin can cause damage to the brains of newborn infants.
    D. Bilirubin contains methyl and vinyl groups
    E. Bilirubin does not contain iron
A

A. Bilirubin is a cyclic tetrapyrrole

Bilirubin is a linear tetrapyrrole.

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11
Q 
18. She had noted that her stools had been very pale for some time. Lab tests revealed a very high level of direct bilirubin, and also elevated urinary bilirubin. The plasma level of alanine aminotransferase (ALT) was only slightly elevated, whereas the level of alkaline phosphatase was markedly elevated. Abdominal ultrasonography revealed no evidence of gallstones. Of the following, which is most likely the diagnosis?
A. Gilbert Syndrome
B. Hemolytic anemia
C. Type I Crigler-Najjar syndrome
D. Carcinoma of the pancreas
E. Infectious hepatitis
A

D. Carcinoma of the pancreas

The severe jaundice, upper abdominal pain, and weight loss plus the lab results indicating an obstructive type of jaundice are consistent with cancer of the pancreas.

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12
Q
  1. Which one of the following statements about beta-gamma methylene and beta-gamma imino derivatives of purine and pyrimidine triphosphates is CORRECT?
    A. They are potential anticancer drugs
    B. They are precursors of B vitamins.
    C. They readily undergo hydrolytic removal of the terminal phosphate.
    D. They can be used to implicate involvement of nucleotide triphosphates by effects other than phosphoryl transfer.
    E. They serve as polynucleotide precursors.
A

D. They can be used to implicate involvement of nucleotide triphosphates by effects other than phosphoryl transfer.

β,γ-Methylene and β,γ-imino purine and pyrimidine triphosphates do not readily release the terminal phosphate by hydrolysis or by phosphoryl group transfer.

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13
Q
  1. Which one of the following statements about nucleotide structures is NOT CORRECT?
    A. Nucleotides are polyfunctional acids.
    B. Caffeine and theobromine differ structurally solely with respect to the number of methyl groups attached to their ring nitrogens.
    C. The atoms of the purine ring portion of pyrimidines are numbered in the same direction as those of a pyrimidine
    D. NAD+, FMN, “active methionine” and coenzyme A all are derivatives of ribonucleotides
    E. 3’,5’-cyclic AMP and GMP (cAMP and cGMP) serve as second messengers in human biochemistry
A

D. NAD+, FMN, “active methionine” and coenzyme A all are derivatives of ribonucleotides

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14
Q
  1. Which of the following statements about purine nucleotide metabolism is NOT CORRECT?
    A. An early step in purine biosynthesis is the formation of PRPP
    B. Inosine monophosphate (IMP) is a precursor of both AMP and GMP
    C. Orotic acid is an intermediate in pyrimidine nucleotide biosynthesis
    D. Humans catabolize uridine and pseudouridine by analogous reactions
    E. Ribonucleotide reductase converts nucleoside diphosphates to the corresponding deoxyribonucleoside diphosphates.
A

E. Ribonucleotide reductase converts nucleoside diphosphates to the corresponding deoxyribonucleoside diphosphates.

Ribonucleotide reductase converts RIBOnucleoside diphosphates to the corresponding deoxyribonucleoside diphosphates.

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15
Q
  1. Which of the following statements is NOT CORRECT?
    A. Metabolic disorders are only infrequently associated with defects in the catabolism of purines
    B. Immune dysfunction are associated both with a defective adenosine deaminase and with a defective purine nucleoside phosphorylase
    C. The Lesch-Nyhan syndrome reflects a defect in hypoxanthine-guanine phosphoribosyl transferase
    D. Xanthine lithiasis can be due to a severe defect in xanthine oxidase
    E. Hyperuricemia can result from conditions such as cancer characterized by enhanced by tissue turnover.
A

A. Metabolic disorders are only infrequently associated with defects in the catabolism of purines

Metabolic disorders are infrequently associated with
defects in pyrimidine catabolism, which forms water-soluble

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16
Q
  1. Which of the following components are found in DNA?
    A. A phosphate group, adenine, and ribose
    B. A phosphate group, guanine, and deoxyribose
    C. Cytosine and ribose
    D. Thymine and deoxyribose
    E. A phosphate group and adenine
A

B. A phosphate group, guanine, and deoxyribose

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17
Q
  1. The backbone of a DNA molecule consists of which of the following?
    A. Alternating sugars and nitrogenous bases
    B. Nitrogenous bases alone
    C. Phosphate groups alone
    D. Alternating phosphate and sugar groups
    E. Five carbon sugars alone
A

D. Alternating phosphate and sugar groups

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18
Q 
7. The interconnecting bonds that connect the nucleotides of RNA and DNA are termed:
A. N-glycosidic bonds
B. 3’,5’ phosphodiester bonds
C. Phosphomonoesters
D. -2’ phosphodiester linkages
E. peptide nucleic bonds
A

B. 3’,5’ phosphodiester bonds

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19
Q 
8. Which component of the DNA duplex causes the molecule to have a net negative charge at physiological pH?
A. Deoxyribose
B. Ribose	
C. Phosphate groups
D. Chlorine ion
E. Adenine
A

C. Phosphate groups

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20
Q 
11. Name the mechanism through which RNAs are synthesized from DNA
A. Replicational duplication
B. Translation
C. Translesion repair
D. Transesterification
E. Transcription
A

E. Transcription

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21
Q 
13. Name the enzyme that synthesizes RNA from a double stranded DNA template.
A. RNA-dependent RNA polymerase
B.  DNA-dependent RNA convertase
C. RNA-dependent replicase
D. DNA-dependent RNA polymerase
E. Reverse transcriptase
A

D. DNA-dependent RNA polymerase

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22
Q 
20. What is the name of the unusual repeated stretch of DNA localized at the tips of all eukaryotic chromosomes?
A. Kinetochore
B. Telomere
C. Centriole
D. Chromomere
E. Micromere
A

B. Telomere

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23
Q 
21. Given that DNA polymerases are unable to synthesize DNA without a primer, what molecule serves as the primer for these enzymes during DNA replication?
A. Five carbon sugars
B. Deoxyribose alone
C. A short RNA molecule
D. Proteins with free hydroxyl groups
E. Phosphomonoester
A

C. A short RNA molecule

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24
Q 
22. The discontinuous DNA replication that occurs during replication is catalyzed via the production of small DNA segments termed
A. Okazaki fragments	
B. Toshihiro pieces
C. Onishi oligonucleotides
D. Crick strands
E. Watson fragments
A

A. Okazaki fragments

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25
Q 
23. What molecule or force supplies the energy that drives the relief of mechanical strain by DNA gyrase?
A. Pyrimidine to purine conversion
B. Hydrolysis of GTP
C. Hydrolysis of ATP
D. Glycolysis 
E. A proton gradient molecule or force
A

C. Hydrolysis of ATP

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26
Q
  1. Eukaryotic RNA polymerases all have a requirement for a large variety of accessory proteins to enable them to bind promoters and form physiologically relevant transcription complexes; these proteins are termed:
    A. Basal or general transcription factors
    B. Activators
    C. Accessory factors
    D. Elongation factors
    E. Facilitator polypeptides
A

A. Basal or general transcription factors

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27
Q 
31. The DNA segment from which the primary transcript is copied or transcribed is called:
A. Coding strand
B. Initiator methionine domain
C. Translation unit
D. Transcriptome
E. Initial codon
A

A. Coding strand

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28
Q 
33. Modifications to the nucleotides of the pre-tRNAs, pre-rRNAs, and pre-mRNAs occur:
A. Postprandially
B. Postmitotically
C. Pretranscriptionally
D. Posttranscriptionally
E. Prematurely
A

D. Posttranscriptionally

29
Q 
34. RNA polymerase II promoters are located on which side of the transcription unit?
A. Internal
B. 3' downstream
C. Nearest the C-terminus
D. Nearest the N-terminus
E. 5’ upstream
A

E. 5’ upstream

30
Q 
36. The bond connecting the initiation nucleotide of the mRNA with the 5-G Cap structure is a 3:
A. 3’-5’ phosphodiester bridge
B. 5’-5’ triphosphate bridge
C. 3’-3’ triphosphate bridge
D. 3’-5’ triphosphate bridge
E. 5’-3’ triphosphate bridge
A

B. 5’-5’ triphosphate bridge

31
Q
  1. What sequence feature of mature mRNAs listed below is thought to protect mRNAs from degradation?
    A. Special posttranslational modifications
    B. 3’PolyC tail
    C. 5-G Cap
    D. Introns
    E. Lariat structures
A

C. 5-G Cap

32
Q
  1. What could be consequences of inaccurate mRNA splicing be for the RNA?
    A. A single base error at a splice junction will cause a large deletion
    B. A single base error at a splice junction will cause a large insertion
    C. A single base error at a splice junction will cause a large inversion
    D. C and E.
    E. A single base error at a splice junction will change the reading frame and result in mRNA mistranslation.
A

E. A single base error at a splice junction will change the reading frame and result in mRNA mistranslation.

33
Q 
39. What is the macromolecular complex that associates with introns during mRNA splicing?
A. Splicer
B. Dicer	
C. Nuclear body
D. Spliceosome
E. Slicer
A

D. Spliceosome

34
Q
  1. What reaction does reverse transcriptase catalyze?
    A. Translation of RNA to DNA
    B. Transcription of DNA to RNA
    C. Conversion of ribonucleotides into deoxyribonucleotides
    D. Transcription of RNA to DNA
    E. Conversion of a ribonucleotide to deoxynucleotides in the DNA double helix
A

D. Transcription of RNA to DNA

35
Q 
44. If a tRNA has the sequence 5’-CAU-3’, what codon would it recognize?
A. 3’-UAC-5’
B. 3'-AUG-5'
C. 5'-ATG-3’
D. 5’-AUC-3’	
E. 5’-AUG-3’
A

E. 5’-AUG-3’

36
Q 
45. What is on the 3’ end of all functional, mature tRNAs?
A. The cloverleaf shop
B. The anticodon
C. The sequence CCA
D. The codon
A

C. The sequence CCA

37
Q 
46. Most aminoacyl-tRNA synthetases possess an activity that is shared with DNA polymerases. This activity is a \_\_\_\_\_\_\_\_\_\_\_ function.
A. Proofreading
B. Hydrogenase
C. Proteolytic
D. Helicase
E. Endonucleolytic
A

A. Proofreading

38
Q 
47. The three distinct phases of protein synthesis, in the CORRECT order are:
A. Initiation, termination, elongation
B. Termination, initiation, elongation
C. Initiation, elongation, termination
D. Elongation, initiation, termination
E. Elongation, termination, initiation
A

C. Initiation, elongation, termination

39
Q 
48. Which amino acid is the initiating amino acid for essentially all proteins?
A. Cysteine
B. Threonine
C. Tryptophan
D. Methionine	
E. Glutamic acid
A

D. Methionine

40
Q 
49. The initiatior tRNA is placed within the active 80S complex at which of the three canonical ribosomal “sites” during protein synthesis?
A. E site
B. I site	
C. P site
D. A site
E. Releasing factor binding site
A

C. P site

41
Q 
50. Name the enzyme that forms the peptide bond during protein synthesis and define its chemical composition.
A. Pepsynthase, protein
B. Peptidyl transferase, RNA
C. Peptidase, glycolipid	
D. Peptidyl transferase, protein
E. GTPase, glycopeptide
A

B. Peptidyl transferase, RNA

42
Q 
51. Mutations in the middle of an open reading frame that create a stop codon are termed:
A. Frameshift mutation
B. Missense mutation
C. No-nonsense mutation
D. Point mutation
E. Nonsense mutation
A

E. Nonsense mutation

43
Q 
52. What is the directionality of polypeptide synthesis?
A. C terminal to N terminal direction
B. N terminal to 3’direction
C.  N terminal to C terminal direction
D. 3’-5’ direction	
E. 5’-3’ direction
A

C. N terminal to C terminal direction

44
Q 
53. Which of the following cis-acting elements typically resides adjacent to or overlaps with many prokaryotic promoters?
A. Regulatory gene
B. Structural gene(s)
C. Repressor
D. Operator
E. Terminator
A

D. Operator

45
Q 
54. What is the term applied to a segment of a bacterial chromosome where genes for the enzymes of a particular metabolic pathway are clustered and subject to coordinate control?
A. Operon	
B. Operator
C. Promoter
D. Terminal Controller
E. Origin
A

A. Operon

46
Q 
55. What is the term applied to the complete collection of proteins present in a particular cell type?
A. Genome
B. Peptide collection
C. Transcriptome
D. Translatome
E. Proteome
A

E. Proteome

47
Q
  1. Which types of molecules interact with eukaryotic mRNA gene core promoter sites to facilitate the association of RNA polymerase II?
    A. Termination factors
    B. Sequence-specific transcription factors (transactivators)
    C. Elongation factors
    D. GTPases
    E. General, or basal transcription factors
A

E. General, or basal transcription factors

48
Q 
59. Transcription factors bound at enhancers stimulate the initation of transcription at the cis-linked core promoter through the action of intermediaries termed
A. Coactivators
B.  Cotranscription proteins
C. Corepressors
D. Receptors
E. Coordinators
A

A. Coactivators

49
Q 
60. What reactions among transcription proteins greatly expand the diversity of regulatory factors that can be generated from a small number of polypeptides?
A. Recombination
B. Homodimerization
C. Heterozygosity
D. Heterodimerization
E. Trimerization
A

D. Heterodimerization

50
Q 
61. The gene region containing the TATA box and extending to the transcription start site (TSS) is often termed the \_\_\_\_\_\_\_\_\_\_\_
A. Polymerase home
B. Initiator	
C. Start selector
D. Core promoter
E. Operator
A

D. Core promoter

51
Q
  1. Which of the following possible mechanisms for how enhancers can stimulate transcription from great distances are currently thought to be CORRECT?
    A. Enhancers can reversibly excise the intervening DNA between enhancers and promoters
    B. RNA Polymerase II binds avidly to enhancer sequences.
    C. Enhancers unwind DNA
    D. Enhancers can search through DNA and bind directly to the associated core promoter
    E. Enhancers and core promoters are brought into close proximity through DNA loop formation mediated by DNA binding proteins
A

E. Enhancers and core promoters are brought into close proximity through DNA loop formation mediated by DNA binding proteins

52
Q 
63. Which of the following histone amino acids are typically acetylated?
A. Lysine
B. Arginine
C. Asparagine
D. Histidine
E. Leucine
A

A. Lysine

53
Q 
66. Which sequences extend between the 5’methylguanosine cap present on eukaryotic mRNAs to the AUG initiation codon?
A. Stop codon
B. Last exon
C. Last intron
D. 3’UTR
E. 5’UTR
A

E. 5’UTR

54
Q 
67. Which of the following features of eukaryotic mRNA contribute importantly to message half-life?
A. 5’UTR sequences
B. The promoter
C. The operator	
D. 3’UTR and Poly A tail
E. The first intron
A

D. 3’UTR and Poly A tail

55
Q
  1. Regarding membrane lipids, select the one FALSE answer:
    A. The major phospholipid by mass in human membranes is generally phosphatidylcholine
    B. Glycolipids are located on the inner and outer leaflets of the plasma membrane
    C. Phosphatidic acid is a precursor of phosphatidylserine, but not of sphingomyelin
    D. Phosphatidylcholine and phosphatidylethanolamine are located primarily on the outer leaflet of the plasma membrane
    E. The flip-flop of phospholipids in membranes is very slow
A

B. Glycolipids are located on the inner and outer leaflets of the plasma membrane

Glycolipids are located on the outer leaflet.

56
Q
  1. Regarding membrane proteins, select the one FALSE answer:
    A. Because of steric considerations, alpha-helices cannot exist in membranes
    B. A hydropathy plot helps one to estimate whether a segment of a protein is predominantly hydrophobic or hydrophilic
    C. Certain proteins are anchored to the outer leaflet of plasma membranes via glycophosphatidylinositol (GPI) structures
    D. Adenyl cyclase is a marker enzyme for the plasma membrane
    E. Myelin has a very high content of lipid compared with protein.
A

A. Because of steric considerations, alpha-helices cannot exist in membranes

Alpha-helices are major constituents of membrane proteins.

57
Q
  1. Regarding membrane transport, select the one FALSE statement:
    A. Potassium has a lower charge density than sodium and tends to move more quickly through membranes than does sodium
    B. The flow of ions through ion channels is an example of passive transport.
    C. Facilitated diffusion requires a protein transporter.
    D. Inhibition of the Na+ K+-ATPase will inhibit sodium dependent uptake of glucose in intestinal cells
    E. Insulin, by recruiting glucose transporters to the plasma membrane, increases uptake of glucose in fat cells but not in muscle
A

E. Insulin, by recruiting glucose transporters to the plasma membrane, increases uptake of glucose in fat cells but not in muscle

Insulin also increases glucose uptake in muscle.

58
Q
  1. Regarding the Na+K+-ATPase, select the one FALSE answer:
    A. Its action maintains the high intracellular concentration of sodium compared with potassium
    B. It can use as much as 30% of the total ATP expenditure of a cell.
    C. It is inhibited by digitals, a drug that is useful in certain cardiac conditions
    D. It is localized in the plasma membrane of cells
    E. Phosphorylation is involved in its mechanism of action, leading to its classification as a P-type ATP-driven active transporter
A

A. Its action maintains the high intracellular concentration of sodium compared with potassium

Its action maintains the high intracellular concentration of
potassium compared with sodium.

59
Q
  1. What molecules enable cells to respond to a specific extracellular signaling molecule?
    A. Specific receptor carbohydrates localized to the inner plasma membrane surface
    B. Plasma lipid bilayer
    C. Ion channels
    D. Receptors that specifically recognize and bind that particular messenger molecule
    E. Intact nuclear membranes
A

D. Receptors that specifically recognize and bind that particular messenger molecule

60
Q 
6. Indicate the term generally applied to the extracellular messenger molecules that bind to transmembrane receptor proteins:
A. Competitive inhibitor 
B. Ligand
C. Scatchard curve
D. Substrate
E. Key
A

B. Ligand

61
Q 
13. The subunits of hetertrimeric G proteins are called the \_\_\_\_\_, \_\_\_\_\_\_, and \_\_\_\_\_\_ subunits.
A. α, β, and χ
B. α, β, and δ
C. α, γ, and δ
D.α, β, and γ
E. γ, δ, and η
A

D.α, β, and γ

62
Q 
14. Of the receptors listed below, which can conduct a flow of ions across the plasma membrane when bound to their cognate ligand?
A. Receptor tyrosine kinases (RTKs)
B. G protein-coupled receptors (GPCRs)
C. G protein coupled receptors
D. Steroid hormone receptors
E. Ligand-gated channels
A

E. Ligand-gated channels

63
Q 
15. Which of the following is NOT a natural ligand that binds to G protein-coupled receptors?
A. Hormones
B. Steroid hormones
C. Chemoattractants
D. Opium derivatives
E. Neurotransmitters
A

B. Steroid hormones

64
Q 
17. Which heterotrimeric G proteins couple receptors to adenyl cyclase via the activation of GTP bound G-alpha subunits?
A. Gs family
B. Gq family
C. Gi family
D. G12/13 family
E. Gx family
A

A. Gs family

65
Q
  1. What must happen in order to prevent overstimulation by a hormone?
    A. Hormones must be degraded
    B. G proteins must be recycled and then degraded
    C. Receptors must be blocked from continuing to activate G proteins
    D. Receptors must dimerize
A

C. Receptors must be blocked from continuing to activate G proteins

66
Q 
19. Which of the following hormones termed the “flight or fight” hormone is secreted by the adrenal medulla?
A. Epinephrine
B. Oxytocin
C. Insulin	
D. Glucagon
E. Somatostatin
A

A. Epinephrine

67
Q 
20. Which hormone is secreted by alpha-cells in the pancreas in response to low blood glucose levels?
A. Insulin
B. Glucagon
C. Estradiol
D. Epinephrine
E. Somatostatin
A

B. Glucagon

68
Q 
21. In liver cells the expression of genes encoding gluconeogenic enzymes such as phosphoenolpyruvate carboxykinase is induced in response to which of the following molecules?
A. cGMP
B. Insulin
C. ATP	
D. cAMP
E. Cholesterol
A

D. cAMP

69
Q
  1. What happens to protein kinase A (PKA) following the binding of cAMP?
    A. The regulatory subunits of PKA dissociate, thereby activating the catalytic subunits
    B. PKA catalytic subunits bind to two regulatory subunits, thereby activating the catalytic subunits
    C. The inhibitory regulatory subunits dissociate from the catalytic subunits, completely inactivating the enzyme
    D. The stimulatory regulatory subunits dissociate from the catalytic subunits, inhibiting the enzyme
    E. Phosphodiesterase binds to the catalytic subunits, which results in enzyme inactivation.
A

A. The regulatory subunits of PKA dissociate, thereby activating the catalytic subunits

Biochemistry (15 decks)

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