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Biochemistry 5th LE > Biochemistry 5th LE 2015 > Flashcards

Biochemistry 5th LE 2015 Flashcards

1
Q 
The most common enzyme deficiency in newborn females with ambiguous genitalia is
A.	CYP 11
B.	CYP 17
C.	CYP 19
D.	CYP 21
A

D. CYP 21

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2
Q

The androgen receptor has this unique feature:
A. Does not utilize heat shock protein
B. Expressed in the X-chromosome
C. Localization signal is in the variable region
D. Undergoes recycling by endocytosis

A

B. Expressed in the X-chromosome

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3
Q

Patients with precocious puberty are treated with hormone having this structure:
A. Decapeptide with an N-terminal pyroglutamate
B. Glycoprotein with multiple sialic-acid residues
C. Octopeptide with a cysteine disulfide bridge
D. Polypeptide with alpha and beta subunit

A

A. Decapeptide with an N-terminal pyroglutamate

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4
Q 
Which is correct regarding the structure of estradiol?
A.	A ring with a double bond at C4-C5
B.	Contains 18 carbon atoms
C.	Contains hydroxyl group at C20
D.	D ring is cyclohexane
A

B. Contains 18 carbon atoms

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5
Q

Which is correct about estrogen metabolism in the fetus?
A. Fetal adrenal gland has aromatase that converts testosterone to estradiol
B. Fetal adrenal gland has 5-alpha reductase that converts testosterone to estriol
C. Metabolizes 16 alpha-hydroxyDHEA to estriol by plancental aromatase
D. Metabolizes desmolase for in-situ synthesis of cholesterol by the placenta

A

C. Metabolizes 16 alpha-hydroxyDHEA to estriol by plancental aromatase

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6
Q

Which is TRUE regarding SHBG transport of gonadal steroids?
A. Binds estrogens and progestins equally
B. Binds the active form of testosterone
C. Increases estriol concentration in peripheral tissue
D. Decreases the free concentration of serum testosterone

A

D. Decreases the free concentration of serum testosterone

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7
Q

Which statement correctly describes mitochondrial CP450 enzymes?
A. Found in the outer mitochondrial membrane
B. Involve in steroid dehydrogenation reactions
C. Utilize NADH for electron delivery
D. Requires “adrenodoxin” as an electron shuttle

A

D. Requires “adrenodoxin” as an electron shuttle

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8
Q

Progesterone shows the highest binding affinity to this transport protein
A. Albumin
B. Cortisol-binding globulin
C. Sex-hormone binding globulin
D. Testosterone-estrogen binding globulin

A

D. Testosterone-estrogen binding globulin

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9
Q 
Which condition decreases SHBG production?
A.	Estrogens
B.	Liver diseases
C.	Hyperthyroidism
D.	Advancing age
A

D. Advancing age

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10
Q 
These CYP450 enzymes are involved in gonadal hormone synthesis EXCEPT:
A.	CYP11
B.	CYP17
C.	CYP19
D.	CYP21
A

D. CYP21

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11
Q

How do you explain the development of gynecomastia in a 55-year-old chronic alcoholic with liver cirrhosis?
A. Peripheral aromatization of androgens to estrogens
B. Unsuppressed negative feedback inhibition from testosterone
C. Positive feedback causing …. of ….receptors
D. Hypersecretion of gonadotropin due to a pituitary tumor

A

A. Peripheral aromatization of androgens to estrogens

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12
Q

The inflammatory effect of some receptor tyrosine kinase (RTK) is due to:
A. Lack of response to biologic effects of Interleukin-1
B. Overproduction of interleukin-1
C. Reaction between IL-1 and IL-1 receptor antagonist (IL-Ra)
D. Resistance to Interleukin-1 antagonist (IL-1a)

A

B. Overproduction of interleukin-1

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13
Q

Persistent attachment of GTP to G alpha subunit results to:
A. Relaxation of the P loop of switch 1 and 2 region
B. Resistance to hydrolysis of gamma phosphate group
C. Termination of the signal occurs
D. Inactivation of adenylyl cyclase

A

B. Resistance to hydrolysis of gamma phosphate group

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14
Q 
The major regulator of PTH biosynthesis is the:
A.	Rate of degradation of the proPTH
B.	Level of plasma ionized calcium
C.	Number of available calcium receptors
D.	Generation of proteolytic enzymes
A

B. Level of plasma ionized calcium

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15
Q 
Patients with End stage renal disease have delayed bone aging due to:
A.	Increased calcitonin levels
B.	Increased serum calcium levels
C.	Decreased 1,24-dihydrocholecalciferol
D.	Decreased 1,25-dihydrocholecalciferol
A

D. Decreased 1,25-dihydrocholecalciferol

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16
Q 
Which is the correct hormone:amino acid peptide pair?
A.	PTH:32AA
B.	Calcitonin:32AA
C.	PreproPTH:32AA
D.	PTH related protein:32AA
A

D. PTH related protein:32AA

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17
Q

Which is TRUE about the metabolism of PTH?
A. It is secreted as an 84 amino acid single chain polypeptide.
B. Its polypeptide chain is composed mainly of amino acid residues.
C. The preproPTH is synthesized in the Golgi apparatus.
D. The synthesis is dependent on the levels of alkaline phosphatase.

A

A. It is secreted as an 84 amino acid single chain polypeptide.

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18
Q
  1. The following relationship is correct, EXCEPT:
    A. Serum calcium inversely affects PTH secretion.
    B. Hypermagnesemia can inhibit PTH secretion.
    C. Increased 1,25 –dihydroxyvitamin D inhibits PTH secretion.
    D. Serum phosphate directly affects PTH secretion.
A

D. Serum phosphate directly affects PTH secretion.

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19
Q

Which of the following statements is TRUE about the vitamin D metabolism?
A. 7-dehydrocholesterol is synthesized in the liver.
B. The principal fat storage form of vitamin –D is ergocalciferol.
C. The major circulating vitamin D is 24-hydroxyvitamin D.
D. The kidney is the major source of 1,25-dihydroxycholecalciferol.

A

D. The kidney is the major source of 1,25-dihydroxycholecalciferol

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20
Q

. O.B., 21-years-old female has a BMI of 32kg/m2. Lab results: increased TAGs, decreased HDL and increased VLDL.

The present condition of O.B. can be explained by a decreased:
A. Production of thermogenin by adipocytes
B. Release of leptin from adipose cells
C. Synthesis of adiponectin from adipocytes
D. Sensitivity of orexigenic nucleus to leptin

A

D. Sensitivity of orexigenic nucleus to leptin

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21
Q

O.B., 21-years-old female has a BMI of 32kg/m2. Lab results: increased TAGs, decreased HDL and increased VLDL.

The increase of TAGs of O.B. is a result of an increased:
A. Production of thermogenin in adipocytes
B. Release of leptin from the adipose tissue
C. Synthesis of adiponectin from adipocytes
D. Sensitivity of orexigenic nucleus to leptin

A

A. Production of thermogenin in adipocytes

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22
Q

What is the difference between the effects of thyroid hormone (TH) and growth hormone (GH) on the skeletal muscles?
A. Glucose output: increased in TH, increased in GH
B. Glucose uptake: decreased in TH, increased in GH
C. Glucose utilization: increased in TH, increased in GH
D. Protein synthesis: decreased in TH, increased in GH

A

B. Glucose uptake: decreased in TH, increased in GH

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23
Q

What best describes the receptor of thyroid hormones?
A. Unoccupied receptor is attached with HSP.
B. Unoccupied receptor is coupled with RXR.
C. TH-receptor complex directly stimulate TRE.
D. TH-receptor complex dimerizes with RXR.

A

D. TH-receptor complex dimerizes with RXR.

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24
Q

M.D. 40-years-old female is a diagnosed case of DM 2. Her BMI=30 kg/m2, FBS= 157 mgs. Lipid profile: increases TAGs and increases VLDL.

The immediate reason for an increase in blood glucose after M.D. partakes of a full meal is a result of
A. Active phosphoenolpyruvate carboxyl kinase
B. Decreased glucose uptake by muscles and adipocytes
C. Inactive acetyl COA carboxylase in liver
D. Increase glucose output from skeletal muscle

A

B. Decreased glucose uptake by muscles and adipocytes

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25
Q

M.D. 40-years-old female is a diagnosed case of DM 2. Her BMI=30 kg/m2, FBS= 157 mgs. Lipid profile: increases TAGs and increases VLDL.

After an 16-hour fast, which of the following enzymes of M.D. are inactive?
A.	Acetyl COA carboxylase
B.	Glycogen phosphorylase
C.	HMG-COA synthase
D.	Hormone sensitive lipase
A

B. Glycogen phosphorylase

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26
Q

M.D. 40-years-old female is a diagnosed case of DM 2. Her BMI=30 kg/m2, FBS= 157 mgs. Lipid profile: increases TAGs and increases VLDL.

The lipid profile of M.D. can be explained by which mechanism?
A. Decreased clearance of VLDL from blood by the liver
B. FFAs in the liver diverted to TAG & VLDL synthesis
C. Inhibition of hormone sensitive lipase  (-) lipolysis
D. Increased synthesis of Apo A1 and Apo A by the liver

A

B. FFAs in the liver diverted to TAG & VLDL synthesis

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27
Q

M.D. 40-years-old female is a diagnosed case of DM 2. Her BMI=30 kg/m2, FBS= 157 mgs. Lipid profile: increases TAGs and increases VLDL.

The complete oxidation of glucose in the case of M.D. is inhibited due to decreased transcription and activity of which enzyme?
A.	Acetyl COA carboxylase
B.	Hexokinase II & IV
C.	HMG COA reductase
D.	Pyruvate carboxylase
A

B. Hexokinase II & IV

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28
Q

What branch of the signaling pathway is defective when there is a sequestration of GLUT4 in the intracytoplasmic vesicles?
A. Phosphorylated-IRS1 -> Gt2/m808 -> mTOR
B. phosphorylated-IRS1 -> P13K->PDK1 -> PKB
C. Phosphorylated-IRS1 -> P13K->PDK1 -> mTOR
D. phosphorylated-IRS1 -> P13K->PDK1 -> MEK

A

B. phosphorylated-IRS1 -> P13K->PDK1 -> PKB

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29
Q

What branch of signaling pathway of insulin explains the increase of key enzymes of glycolysis?
A. Phosphorylated-IRS1 -> Gt2/m808 -> mTOR
B. Phosphorylated-IRS1 -> P13K->PDK1 -> mTOR
C. Phosphorylated-IRS1 -> P13K->PDK1 -> MAPK
D. Phosphorylated-IRS1 -> P13K->PDK1 -> PKB

A

C. Phosphorylated-IRS1 -> P13K->PDK1 -> MAPK

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30
Q 
How do you explain the occurrence of hyperglycemia in a new born?
A.	Persistently closed K+ channels
B.	Persistently open K+ channels
C.	Defect in the insulin signaling
D.	Downregulation of GLUTs
A

A. Persistently closed K+ channels

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31
Q 
Insulin stimulates the storage of excess glucose by activation of which of the following key enzymes?
A.	Pyruvate dehydrogenase
B.	Hormone sensitive lipase
C.	HMG COA synthase
D.	Acetyl COA carboxylase
A

D. Acetyl COA carboxylase

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32
Q 
Which of the following hormones are not released due to somatostatin?
A.	ACTH
B.	Cortisol
C.	Epinephrine
D.	Glucagon
A

D. Glucagon

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33
Q

What is the signaling pathway of somatostatin?
A. Activated adenylate cyclase -> increase cAMP -> active PKA
B. Increased AMP -> (+) AMPK -> phosphorylation of key CHON
C. (+) Gi -> (-) adenylate cyclase -> decreased CAMP -> inactive PKA
D. JAK-STATs -> regulation of gene transcription

A

C. (+) Gi -> (-) adenylate cyclase -> decreased CAMP -> inactive PKA

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34
Q

Growth hormone increases blood glucose by what mechanism?
A. Decrease glucose uptake by muscle
B. Decrease glucose output by the liver
C. Increase glucose utilization in muscle
D. Increase glycogen breakdown in liver

A

A. Decrease glucose uptake by muscle

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35
Q 
Glucagon inhibits glycolysis but stimulates gluconeogenesis because of a decreased amount of which molecule?
A.	Acetyl COA
B.	F 1, 6-bisphosphate
C.	F 2, 6-bisphosphate
D.	Glucose 6-phosphate
A

C. F 2, 6-bisphosphate

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36
Q 
Which of the following are the effects of glucagon?
A.	Adipocytes:decreased lipogenesis
B.	Brain:increased glucose uptake
C.	Liver:decreased glucose export
D.	Liver: increased glycogenolysis
A

D. Liver: increased glycogenolysis

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37
Q

Which best describes the signaling pathway of glucagon?
A. GTP-Gsa -> (+) adenylate cyclase -> cAMP -> active PKA
B. GDP-Gsa -> (+) adenylate cyclase -> increase cAMP -> active PKA
C. Increased AMP -> active AMPK -> phosphorylation of CHON
D. Stimulated Gsa -> (-) adenylate cyclase -> cAMP -> inactive PKA

A

A. GTP-Gsa -> (+) adenylate cyclase -> cAMP -> active PKA

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38
Q 
How does insulin terminate the signaling pathway of glucagon when there is an increase in blood glucose?
A.	Activation of phosphodiesterase
B.	Inactivation of protein phosphatases
C.	Stimulation of PTEN
D.	Translocation of GLUTs
A

A. Activation of phosphodiesterase

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39
Q

What is the mechanism by which glucagon, epinephrine and TSH regulate gene transcription?
A. Stimulated Gsa -> (-) adenylate cyclase -> decrease cAMP-> inactive PKA
B. GDP-Gsa -> (+) adenylate cyclase -> increase cAMP -> active PKA
C. Increase AMP -> active AMPK -> phosphorylation of CHON
D. Active PKA goes to nucleus -> active CREB -> CBP -> CRE

A

D. Active PKA goes to nucleus -> active CREB -> CBP -> CRE

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40
Q

Which is correct about the mechanism of catecholamines?
A. Cortisol decreases activity of PNMT -> decreased synthesis of epinephrine
B. Degradation is by endocytosis of hormone-receptor complex.
C. Epinephrine manifests greater affinity to beta rather than alpha receptors.
D. Release of catecholamines occurs when there is a decreased Ca2+ influx.

A

C. Epinephrine manifests greater affinity to beta rather than alpha receptors.

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41
Q 
Epinephrine increases the fuel supply to the skeletal muscles by 
A.	(+) Glycogenolysis
B.	(+) Hexokinase
C.	Decreased glucose uptake
D.	Decreased F 2,6-bisphosphate
A

A. (+) Glycogenolysis

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42
Q

Epinephrine and glucagon increases free fatty acids, which then undergo beta oxidation, by the activation of which enzyme?

A. Carnitine Palmitoyl Transferase 1
B. Hormone Sensitive Lipase
C. .. Lipase
D. Pyruvate Dehydrogenase Kinase

A

B. Hormone Sensitive Lipase

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43
Q

Which is correct about the receptors of Cortisol?

A

Answer: In the cytosol, the receptor is complexed with heat shock proteins.

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44
Q

CC, a 24-year-old female is on chronic oral glucocorticoid therapy due to chronic asthma. After 2 months, she presented with trunkal obesity, thin extremities ad weakness. FBS = 156 kg/m2. No history of DM.

The elevated FBS of CC is a result of:
A. Activation of glycogen phosphorylase
B. Activation of glycogen synthase
C. Decreased oxidation of glucose in muscles
D. increased amount of PEPCK in liver and kidneys

A

D. increased amount of PEPCK in liver and kidneys

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45
Q

CC, a 24-year-old female is on chronic oral glucocorticoid therapy due to chronic asthma. After 2 months, she presented with trunkal obesity, thin extremities ad weakness. FBS = 156 kg/m2. No history of DM.

Explain the thin extremities of CC compared to her trunk.
A. Activation of glycogen phosphorylase
B. Decreased glucose uptake by muscles
C. Increased lypolysis in peripheral tissues
D. Increased lipogenesis in extremities

A

C. Increased lypolysis in peripheral tissues

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46
Q

What is the effect of adiponectin on the ff target organs?
A. Liver = decreased gluconeogenesis
B. Liver = increased lipogenesis
C. Muscle = decreased glycolysis
D. Muscle = increased fatty acid oxidation

A

D. Muscle = increased fatty acid oxidation

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47
Q 
GTP is the precursor of:
A.	Coenzyme A
B.	FAD
C.	NAD
D.	Tetrahydrobiopterin
A

D. Tetrahydrobiopterin

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48
Q 
The substrate of ribonucleotide reductase is:
A.	Inosinate
B.	Orotidylate
C.	Thymidylate
D.	Uridylate
A

D. Uridylate

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49
Q 
The activation of this anti-metabolite requires HGPRT.
A.	Allopurinol
B.	5-fluorouracil
C.	Mercaptopurine
D.	Methotrexate
A

C. Mercaptopurine

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50
Q 
Select the correct nucleotide pair in the catalytic and regulatory areas of R1 subunit of ribonucleotide reductase if ADP is the substrate.
A.	ATP, dATP
B.	ATP, dCTP
C.	ATP, dGTP
D.	ATP, dTTP
A

C. ATP, dGTP

51
Q

This purine nucleoside is a substrate of the salvage pathway.
A. Adenosine
B. Inosine
C. Guanosine

A

A. Adenosine

52
Q 
PRPP will form a nucleotide if bonded with:
A.	Hypoxanthine
B.	Inosine
C.	Uridine
D.	Xanthine
A

A. Hypoxanthine

53
Q

Pyrimidine nucleotide that is NOT present in DNA:
A. CTP
B. TTP
C. UTP

A

C. UTP

54
Q 
In pyrimidine de novo synthesis, the substrate of decarboxylase enzyme is:
A.	Dihydroorotate
B.	Orotate
C.	Orotidylate
D.	Uridylate
A

C. Orotidylate

55
Q 
In the conversion of ribonucleotides to deoxyribonucleotides by ribonucleotide reductase, the initial step is the generaton of: 
A.	Dithiol group on R1 subunit
B.	Disulfide group of R1 subunit
C.	Thiol group on R2 subunit
D.	Thyil group on R2 subunit
A

B

56
Q

This nucleotide derivative contains both a pyrimidine and purine ring in this structure.
A. Coenzyme A
B. FAD
C. NAD

A

C. NAD

57
Q 
To provide substrates for DNA polymerization, nucleotides undergo this reaction at 2’ position.
A.	Condensation
B.	Dehydration
C.	Hydroxylation
D.	Reduction
A

D. Reduction

58
Q 
To form a purine nucleoside, the N-glycosidic bond should be between:
A.	N1, C1
B.	N1, C5
C.	N9, C1
D.	N9, C5
A

C. N9, C1

59
Q 
The final step in purine de novo synthesis is the formation of a chemical bond between: 
A.	N1, C2
B.	N3, C2
C.	N7, C8
D.	N9, C8
A

B

60
Q 
In purine de novo synthesis, the step requiring ATP is:
A.	Formyl group transfer
B.	Closure of imidazole ring
C.	Closure of purine ring
D.	Release of fumarate
A

B. Closure of imidazole ring

61
Q 
In the synthesis of FAD, the number of ATP required is:
A.	1
B.	2
C.	3
D.	4
A

B. 2

62
Q 
The final step in the synthesis of coenzyme A involves:
A.	Dephosphorylation of carbon 2
B.	Formation of pyrophosphorylase
C.	Phosphorylation of carbon 2’
D.	Phosphorylation of carbon 2
A

C. Phosphorylation of carbon 2’

63
Q 
The cytotoxic effect of methotrexate inhibits the formation of:
A.	Dihydrofolate
B.	dCTP
C.	dUMP
D.	Tetrahydrofolate
A

D. Tetrahydrofolate

64
Q 
In RNA degradation, nuclease will break which chemical bond:
A.	Hydrogen bond
B.	N-glycosidic bond
C.	Phospoanhydride bond
D.	Phosphoester bond
A

D. Phosphoester bond

65
Q

The cytotoxic effects of FdUMP is mainly due to:
A. Altered pre-mRNA splicing to mature mRNA
B. Covalent binding with thymidylate synthase
C. Interference and inhibition of DNA polymerization
D. Non maturation of 45S precursor rRNA to 18S and 28S

A

B. Covalent binding with thymidylate synthase

66
Q

The Watson-Crick DNA is stabilized by the:
A. G-quartet repeats involving telomeres
B. Hydrogen bonds between nucleobases
C. Phosphate-ribose bond between dNTPs
D. Positive supercoiling of the right-handed helix

A

C. Phosphate-ribose bond between dNTPs

67
Q

Processivity of DNA replication refers to the capacity of the polymerizing enzyme to:
A. Adhere to Chargaff’s the base – pairing rule
B. Attach to the template during elongation
C. Form a 5’ to 3’ phosphodiester bond
D. Repair mismatches in the base pairs

A

B. Attach to the template during elongation

68
Q

The mitochondrial DNA is characterized as:
A. Containing 37 genes coding for enzymes for oxidative phosphorylation
B. Involved in the transmission of disease from father to daughter
C. Organized as a linear genome similar to the nuclear DNA
D. Replicated following the principle of abnormal DNA replication

A

D. Replicated following the principle of abnormal DNA replication

69
Q 
70.	Nucleosomes are connected to one another by:
A.	Centromere
B.	Chromatin
C.	Linker DNA
D.	Mitotic spindle
A

C. Linker DNA

70
Q

Which is a basic principle that describes DNA replication?
A. Accuracy is a function of the pairing between bases.
B. Each single-stranded DNA (ssDNA) acts as the template for a new daughter strand.
C. Fidelity results from the 5’ to 3’ polarity of elongation.
D. Processivity refers to the exonuclease activity of the enzyme.

A

B. Each single-stranded DNA (ssDNA) acts as the template for a new daughter strand.

71
Q 
72.	This DNA pol III subunits share the same catalytic activity as proliferating cell nuclear antigen.
A.	α
B.	β
C.	γ
D.	Θ
A

B. β

72
Q

The initiation of replication in prokaryotes requires:
A. Single RNA primer each for both daughter DNA strands
B. Release of positive supercoil by topoisomerase II
C. Sliding of helicase along both strands to open double-stranded DNA (dsDNA)
D. DnaB/DnaG activity to prevent reannealing of dsDNA

A

B. Release of positive supercoil by topoisomerase II

73
Q

Which statement is true regarding the trombone model of replication?
A. The template strand is looped out within a subunit of DNA pol III.
B. It is elongated simultaneously in the same direction as the leading strand.
C. The complement DNA strand is elongated from 3’ to 5’ direction.
D. Facilitates the uninterrupted addition of dNTPs

A

A. The template strand is looped out within a subunit of DNA pol III.

74
Q 
RNA polymerase moves away from the promoter site during:
A.	Chain elongation
B.	Chain initiation
C.	Promoter clearance
D.	Template binding
A

C. Promoter clearance

75
Q 
The sequence of recruitment of the licensing factors during eukaryotic replication is:
A.	Cdc6-CRC-Cdt1-MCM
B.	Cdt1-CRC-Cdc6-MCM
C.	MCM-Cdc6-Cdt1-MCM
D.	CRC-Cdc6-Cdt1-MCM
A

D. CRC-Cdc6-Cdt1-MCM

76
Q 
The mammalian polα/Primase complex prepares the switching to the catalytic activity of pol:
A.	β
B.	δ
C.	ε
D.	γ
A

B. δ

77
Q

Characteristic of the splicing of pre-mRNA:
A. Depends on a conserved region in the template
B. Reaction involves hydrolysis of ATP
C. U1 recognizes the AG sequence of the exon
D. U4 connects 5’ end and 3’ end of two exons

A

B. Reaction involves hydrolysis of ATP

78
Q 
Which sequence of basal transcription factors are recruited to the promoter region?
A.	TBP-TFIIA-TFIIB-TFIIF
B.	TBP-TFIIF-TFIIA-TFIIB
C.	TBP-TFIIB-TFIIA-TFIIF
D.	TBP-TFIIF-TFIIA-TFIIB
A

A. TBP-TFIIA-TFIIB-TFIIF

79
Q

Which transcriptional modification is observed in both prokaryote and eukaryote?
A. Addition of a methylguanosine cap at the 5’ end of pre-mRNA
B. Intervening segments of the pre-mRNA undergoes cleavage.
C. Pre-rRNA transcript folds intramolecularly to form a cloverleaf form.
D. Pre-tRNA contains sequences to form ribosomal complexes.

A

B. Intervening segments of the pre-mRNA

80
Q

Initiation of transcription in the E. Coli is best described as:
A. Binding of AMP or GMP to the β subunit of RNA polymerase
B. Binding of the RNA polymerase core enzyme to +1 base pair
C. Recruitment of transcription factor (TBP) to the promoter site
D. Starting from the promoter region in the coding segment

A

A. Binding of AMP or GMP to the β subunit of RNA polymerase

81
Q 
The pre-mRNA transcript that is produced from a gene with the coding segment 5’AATGGCTCAATA3’ is:
A.	3’TTACCGAGTTAT5’
B.	3’AAUGGCUCAAUA5’
C.	5’TTACCGAGTTAT3’
D.	5’AAUGGCUCAAU3’
A

Bonus

82
Q 
This reaction that allows checkpoints to regulate the cell cycle.
A.	Carboxylation
B.	Methylation
C.	Phosphorylation
D.	Transesterification
A

C. Phosphorylation

83
Q

Errors in DNA replication include:
A. Missense when one base pair is changed resulting in a codon that ends translation.
B. Nonsense when a change in a base pair producing a codon for another amino acid.
C. Replacement of uracil by thymine resulting in transversion.
D. Replacement of guanine by cytosine causing transposition

A

D. Replacement of guanine by cytosine causing transposition

84
Q 
The transcription factor that attaches RNA polymerase II to the template strand is:
A.	TFIID
B.	TFIIE
C.	TFIIF
D.	TFIIH
A

C. TFIIF

85
Q

Which statement describes the posttranscriptional modification of primary mRNA transcript?
A. Attachment of snRPs to the coding units to cleave introns
B. 5’ – 5’ phosphodiester bond by an endonuclease
C. Phosphorylation of carboxy-terminal domain
D. Polymerase attaches multiple ATPs to the 3’terminus

A

D. Polymerase attaches multiple ATPs to the 3’terminus

86
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Calcium as a second messenger readily cause conformational changes in proteins by binding the carboxyl groups of :

  1. Asparagine
  2. Aspartate
  3. Glutamine
  4. Glutamate
A

C

87
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Activated GPCRs have the following features:

  1. Extracellular loops bind to the ligand.
  2. Carboxy terminus is directed associated with G-protein.
  3. Intracellular loops are dephosphorylated.
  4. Amino terminus is translocated intracellularly.
A

A

88
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Select the correct molecule: antagonist pair:
  1. ErbB2: Trastuzumab
  2. IL-1: Anakinra
  3. Her1: Cetuximab
  4. IL-1: Pitrakinra
A

A

89
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

The following chemical reactions are catalyzed by 3-β-hydroxysteroid dehydrogenase and ∆4, 5 isomerase:
  1. Androstenedione → Estrone
  2. Dehydroepiandrosterone → androstenedione
  3. Estrone → Estradiol
  4. Pregnenolone → Progesterone
A

C

90
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

The mutation of the calcium sensor receptor (CaSR) will lead to patients with:

  1. Hypercalcemia
  2. Hypocalcemia
  3. Hypercalciuria
  4. Hypocalciuria
A

B

91
Q

A if 1, 2, 3 are correct
B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Which characteristic/s is/are TRUE of CaSR?
  1. It is located on the surface of the parathyroid cells.
  2. It has a long amino terminus with 3 transmembrane segments.
  3. It is a member of the G protein-coupled receptor family.
  4. Its cystosolic tail has more amino acids than the extracellular chain.
A

B

92
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

The following statement/s is/are TRUE about phosphorus and calcium homeostasis:

  1. PTH stimulates the intestinal absorption of calcium and phosphorus.
  2. Formation of insoluble salts affects the intestinal absorption of Calcium and phosphorus.
  3. Calcium and Phosphates are completely absorbed in the intestine.
  4. Vitamin D is necessary to facilitate absorption in the intestinal tract.
A

C

93
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

The function/s of Vitamin D include/s:

  1. Stimulation of intestinal absorption of Calcium and Phosphate
  2. Promotion of the influx of calcium against a concentration gradient
  3. Ensures proper concentration of Ca and PO4 for deposition as hydroxyapatite
  4. Augments PTH on renal calcium reabsorption
A

E

94
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Which chemical reactions are catalyzed by 17-β-hydroxysteroid dehydrogenase?

  1. Androstenedione → Testosterone
  2. Dehydroepiandrosterone → Androstenedione
  3. Estrone → Estradiol
  4. 17-OH-Pregnenolone → 17-OH-Progesterone
A

B

95
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Glycine contributes to this/these position(s) in the purine ring:
1. 2 2. 4 3. 5 4. 8

A

E

96
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

The rate-limiting enzyme in purine de novo synthesis is inhibited by:
  1. Methotrexate
  2. Azaserine
  3. Aminopterin
  4. 6-mercaptopurine
A

C

97
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

An N-glycosidic bond is present in the following:

  1. Inosine
  2. Cytosine
  3. Adenosine
  4. Hypoxanthine
A

B

98
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

The synthesis of IMP requires these enzymes:

  1. IMP cyclohydrolase
  2. GMP reductase
  3. HGPRT
  4. AMP deaminase
A

E

99
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Uric acid or thiouric acid is the product of these substrates:

  1. Hypoxanthine
  2. 6-mercaptopurine
  3. Xanthine
  4. Inosine
A

B

100
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Aspartate donates nitrogen to these positions in the purine ring:
1. 9 2. 6 3. 3 4. 1

A

C

101
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Select the correct energy source: nucleotide pair both in de novo synthesis and salvage pathway.

  1. GTP: AMP
  2. ATP: AMP
  3. ATP: GMP
  4. None: GMP
A

E

102
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Select the correct substrate: product pair of nuclease.
  1. RNA: thymidylate
  2. RNA: adenylate
  3. DNA: uridylate
  4. DNA: cytidylate
A

C

103
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Prevention of the following are the effects of allopurinol:
  1. Elevation of blood uric acid
  2. Gouty arthritis
  3. Tumor lysis syndrome
  4. Degradation of 6-mercaptopurine
A

E

104
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

In the degradation of pyrimidines, the substrates of uridine phosphorylase include:
  1. Uridine
  2. Deoxythymidine
  3. Deoxycytidine
  4. Dytidine
A

A

105
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Positive allosteric effectors will increase the production of the following:

  1. dCTP
  2. dCMP
  3. dTTP
  4. dUMP
A

C

106
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Substrates of pyrimidine phosphoribosyl transferase in the RBC include:
  1. Uracil
  2. Orotate
  3. Thymine
  4. Cytosine
A

A

107
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Which DNA polymerase III subunit: function pair/s is/are related?

  1. Alpha: phosphodiester bond formation
  2. Tau: clamp on template
  3. Gamma: clamp loader
  4. Theta: exonuclease activity
A

B

108
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

All replication systems require:
  1. Clamp loader
  2. Gyrase
  3. DNA polymerase
  4. FEN-1
A

B

109
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Polymerase switching involves DNA pol:

  1. Beta
  2. Alpha
  3. Epsilon
  4. Delta
A

B

110
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

The nucleosome is organized to contain histone octamer of:
1. H4 2. H3 3. H2B 4. H1

A

B

111
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

De novo synthesis of nucleic acids is catalyzed by:

  1. DNA pol alpha
  2. Primase
  3. DNA pol III
  4. RNA pol I
A

C

112
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Energy driven reactions in replication include:

  1. Introduction of a nick at the ori
  2. Separation of the base pairs
  3. Synthesis of the RNA primer
  4. Phosphodiester bond synthesis
A

E

113
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

A transcription unit encompasses the following regions:
  1. Promoter region
  2. RNA template sequence
  3. Rho factor
  4. Template binding region
A

E

114
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Enzymes that are inhibited by antibacterial drugs:
  1. Topoisomerase II
  2. Topoisomerase I
  3. RNA polymerase
  4. DNA ligase
A

B

115
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Catalytic activity exhibited by both DNA and RNA polymerase:
  1. Correction of mismatches
  2. Hydrogen bond separation
  3. Nicking of the template strand
  4. Phosphodiester bond formation
A

C

116
Q

A if 1, 2, 3 are correct B if 1, 3 are correct
C if 2, 4 are correct D if 4 is correct
E if all are correct

Which enzymes exhibit 5’ to 3’ polarity?

  1. DNA polymerase
  2. Primase
  3. RNA polymerase
  4. Telomerase
A

E

117
Q 
A.	Variable domain
B.	DNA binding domain
C.	Hinge Region
D.	Ligand binding domain
E.	F region

. Contains zinc fingers

A

B. DNA binding domain

118
Q 
A.	Variable domain
B.	DNA binding domain
C.	Hinge Region
D.	Ligand binding domain
E.	F region
Nuclear localization signal
A

C. Hinge Region

119
Q 
A.	Variable domain
B.	DNA binding domain
C.	Hinge Region
D.	Ligand binding domain
E.	F region

Transcription activation

A

A. Variable domain OR

D. Ligand binding domain

120
Q 
A.	Variable domain
B.	DNA binding domain
C.	Hinge Region
D.	Ligand binding domain
E.	F region

Where steroid hormones bind

A

D. Ligand binding domain

121
Q 
A.	Variable domain
B.	DNA binding domain
C.	Hinge Region
D.	Ligand binding domain
E.	F region

Provides flexibility to the structure

A

C. Hinge Region

122
Q

A. JAK/STAT pathway
B. Protein Kinase A
C. Protein Kinase C

GnRH

A

C. Protein Kinase C

123
Q

A. JAK/STAT pathway
B. Protein Kinase A
C. Protein Kinase C

LH

A

B. Protein Kinase A

124
Q

A. JAK/STAT pathway
B. Protein Kinase A
C. Protein Kinase C

Prolactin

A

A. JAK/STAT pathway

Biochemistry 5th LE (4 decks)

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