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Biochemisty Main > 7th-Biochemistry-Exam-DNA-and-RNA-Metabolism-Batch-2026 COPY > Flashcards

7th-Biochemistry-Exam-DNA-and-RNA-Metabolism-Batch-2026 COPY Flashcards

1
Q

Which ganglioside serves as the receptor for cholera toxin in the intestinal cells?
A. GM2
B. GM1
C. GM3
D. GM4

A

B. GM1

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2
Q

The enzyme that is deficient in Niemann Pick’s disease?
A.glucocerebrosidase
B.hexosaminidase A
C. sphingomyelinase
D. §-gaIactocerebrosidase

A

C. sphingomyelinase

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3
Q

Among the following special lipids, which utilizes sphingosine for it synthesis?
A.cardiolipin
B.plasmalogen
C.lecithin
D.sphingomyelin

A

D.sphingomyelin

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4
Q

Which of the following phospholipids acts as a lipotropic agent?
A. phosphatidyl choline
B.phosphatidyl inositol
C.phosphatidyl serine
D.cardiolipin

A

A. phosphatidyl choline

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5
Q

Degradation of a galactocerebroside generates which components?
A.sphingosine + fatty acid + galactose
B.glycerol + fatt:y acids + phosphoric acid + galactose
C.glycerol + fatt:y acids + phosphoric acid + nitrogenous base + galactose
D.sphingosine + fatty acid + phosphoric acid + galactose

A

A.sphingosine + fatty acid + galactose

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6
Q

What is the major component of the lung surfactant?
A.dipalmitoyl lecithin
B.dipalmitoylphosphatidyl serine
C.dipalmtoylcephalin
D.dipalmitoylphosphatidyl inositol

A

A.dipalmitoyl lecithin

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7
Q

Ethanolamine is the nitrogenous base of which phospholipid?
A. cardiolipin
B.phosphatidyl inositol
C.lecithin
D.cephalin

A

D.cephalin

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8
Q

What does semiconservative replication mean?
A.replication of DNA takes place at S phase of the cell cycle
B.a DNA molecule is a hybrid of an old strand and one new strand
C.number of DNA molecules is doubled with every other replication
D.replication of DNA never takes place with 100% accuracy

A

B.a DNA molecule is a hybrid of an old strand and one new strand

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9
Q

What are the components of the final product of DNA replication?
A.mRNA, tRNA, and rRNA molecules
B.a wide variety of proteins
C. DNA molecule
D. 2 DNA molecules, each of which contains one new & one old DNA strand

A

D. 2 DNA molecules, each of which contains one new & one old DNA strand

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10
Q

Meselson and StahI used which technique to prove the semi-conservative manner of replication?
A. equilibrium density gradient centrifugation
B. isopycnic centrifugation
C. differential centrifugation
D. diPerential radioisotope labeling

A

A. equilibrium density gradient centrifugation

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11
Q

Which protein unwinds the DNA double helix in E. coli?
A. Dna A
B. Dna B
C. Dna C
D. DnaG

A

B. Dna B

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12
Q

What is the replication fork?
A. only seen in bacterial cells
B. a Y-shaped structure representing the separated strands of DNA to be replicated simultaneously
C. a site where one DNA strand serves as a template, but the other strand is not replicated
D. is created by the action of the enzyme RNA polymerase

A

B. a Y-shaped structure representing the separated strands of DNA to be replicated simultaneously

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13
Q

Which protein prevents the renaturation of the DNA strands once separated to be used as templates in replication?
A.DNA helicase enzyme
B.SSB proteins
C.DNA polymerases
D . ATP

A

B.SSB proteins

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14
Q

Which enzymes used in replication releases the positive supercoil to form negative supercoils?
A. topoisomerases
B.DNA polymerases
C.RNA polymerases
D.DNA ligases

A

A. topoisomerases

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15
Q

Which is the major polymerizing enzyme of replication in E. coli?
A. DNA polymerase III
B. B. DNA polymerase I
C. DNA polymerase II
D. DNA polymerase IV

A

A. DNA polymerase III

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16
Q

Why does DNA synthesis only proceed in the 5 to 3 direction?
A.DNA polymerases reads the template strand from a 3’ to 5’ direction
B.the 3 “ end of the polynucleotide molecule is more electronegative than the 5 “ end ’G
C. that is the direction in which the two strands of DNA unzip
D. that is the only direction that the polymerase can be oriented

A

A.DNA polymerases reads the template strand from a 3’ to 5’ direction

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17
Q

Which starts the polymerization of each Okazaki fragment?
A.the same RNA primer that began synthesis on the leading strand
B.a DNA primer binding to the template DNA
C. DNA polymerase binding to the template DNA
D. a separate RNA primer

A

D. a separate RNA primer

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18
Q

What is the action of primase in replication?
A. introducing nicks into the DNA double strand in order to prevent the formation of knots
B. hydrolyzing ATP to facilitate DNA unwinding
C. synthesizes short strands of RNA at the site of replication initiation
D. forming a replication fork in the DNA double helix.

A

C. synthesizes short strands of RNA at the site of replication initiation

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19
Q

Which enzyme creates the phosphodiester bonds between Okazaki fragment?
A.RNA polymerase
B.DNA ligase
C. DNA polymerase
D. RNA ligase

A

B.DNA ligase

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20
Q

How is the E. coli chromosome replicated?
A. linear DNA molecule is replicated from multiple origins of replication bidirectionally.
B. linear DNA molecule is replicated from one origin of replication bidirectionally.
C. circular DNA molecule is replicated from one origin of replication bidirectionally
D. circular DNA molecule is replicated from one origin of replication unidirectionally

A

C. circular DNA molecule is replicated from one origin of replication bidirectionally

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21
Q

In which way are the chromosomes of eukaryotic cells replicated?
A. the linear DNA, from multiple origins of replication bidirectionally
B. the linear DNA, from one origin of replication bidirectionally
C. the circular DNA from multiple origins of replication bidirectionally
D. the circular DNA from one origin of replication bidirectionally

A

A. the linear DNA, from multiple origins of replication bidirectionally

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22
Q

Use the figure to answer the corresponding questions.
Which is the correct designation for the DNA strand labeled A is:


A. the leading strand
B. a parental strand
C. Okazaki fragments
D. DNA polymerase

A

C. a parental strand

23
Q

What molecule are the segments labeled F in the figure above and what are their function?

A.DNA pol 1, synthesizing the leading strand
B.DNA B,forming the replication fork
C.RNA, initiating DNA synthesis
D.helicase, unwinding the DNA double helix

A

C.RNA, initiating DNA synthesis

24
Q

Capable of folding back on itself like a hairpin and thus acquiring double-stranded characteristics
A. DNA
B. RNA
C. Both DNA and RNA
D. Neither

A

B.RNA

25
Q

The renal stones in the Pediatric patient with classic xanthinuria were analyzed using?
a.KUB ultrasound
b.X-ray diffractometer
c.ESWL
d.Urine microscopy

A

b.X-ray diffractometer

26
Q

What detail, that is included in the history of the child with urinary stones found in his diaper, would point to a gene defect?
a. Nausea, vomiting, discomfort
b. Hematuria and passage of stones
c. Parents are relatives
d. Seven months of UTI

A

c. Parents are relatives

27
Q

Which intermediate is shared both for the synthesis of phospholipids and triacylglycerols?
A. 1,2 diacyglycerol
B.cholesterol
C.HMGCoA
D.glycerol 3 PO4

A

A. 1,2 diacyglycerol

28
Q

A 3 year old child was brought to the medical center and found to have hepatosplenomegaly, with ataxia, dysarthria, dysphagia, dystonia sometime going into gelastic cataplexy with laughing, supranuclear gaze, dementia and sometimes seizures. What is the nature of the dis- ease?
A. Guacher‘s
B. Niemann Pick’s
C. Krabbe’s
D. Tay Sach‘s

A

B. Niemann Pick’s

29
Q

Among the following special lipids, which is a glycerophospholipid?
A.cardiolipin
B.galactosyl ceramide
C. GN2
D. sphingomyelin

A

A.cardiolipin

30
Q

Which protein forms the segment labelled letter D in the figure above and what is its function?
A.DNA ligase, linking short DNA segments
B.DNA pol III, synthesizing the leading strand
C.Helicase, forming the replication fork G D. Histones, forming nucleosomes

A

A.DNA ligase, linking short DNA segments

31
Q

What are the segments signified by the letter E in the figure above are, and give how many nucleotides make them?
A.leading fragments, many
B.Okazaki fragments, 1000
C.replication forks, two
D.nucleosomes, eight forming an octamer

A

B.Okazaki fragments, 1000

32
Q

Which is an important feature of the E. coli DNA polymerase III?
A.can initiate replication without a primer
B.is efficient at nick translation
C.is the major polymerizing enzyme in DNA replication
D.represents over 90% of the DNA polymerase activity in E. coli cells

A

C.is the major polymerizing enzyme in DNA replication

33
Q

Which is the activity carried by 5’ to 3’ exonuclease actvity of E. coli DNA polymerase I?
A. synthesis of the primers at the DNA replication origin
B. synthesizing the lagging strand
C. proofreading of the replication process
D. polymerizing the gaps in between Okazaki fragments

A

D. polymerizing the gaps in between Okazaki fragments

34
Q

Which enzyme removes the RNA primer during replication?
A.DNA polymerase IV
B.RNaseH of the DNA polymerase I
C. DNA ligase
D. DNA polymerase II

A

B.RNaseH of the DNA polymerase I

35
Q

The lagging daughter strand of DNA is synthesized in what appears to be the “wrong” direction. How is this synthesis accomplished?
A.synthesizing short Okazaki fragments in a 5’ — to 3’ direction & forming a loop toward the replication forks
B.synthesizing one short RNA primer to initiate DNA replication
C. using DNA polymerase II to remove RNA primers from Okasaki fragments
D. All of the choices

A

A.synthesizing short Okazaki fragments in a 5’ — to 3’ direction & forming a loop toward the replication forks

36
Q

Which differentiate Pol I from Pol III?
A. Pol I is an RNA polymerase, while Pol III is a DNA polymerase
B. Pol I has a 3’-5’ exonuclease activity, the other does not
C. Pol I has a lower turnover number, the other has 9000 as its turn over #
D. Pol I utilizes RNA primers, the other does not

A

C. Pol I has a lower turnover number, the other has 9000 as its turn over #

37
Q

During replication in E. coli, unwinding of DNA is caused by forming positive supercoils which are removed by:
A. DNA ligase, DNA Gyrase
B.DnaB, DNA polymerase
C.DnaB, DNA Gyrase
D.DnaA, DNA Gyrase

A

C.DnaB, DNA Gyrase

38
Q

Which are the more common secondary structures that might form in the separated DNA strands of replication?
A.basic helix-loop-helix
B.Greek key
C.beta meander
D.stem-loops

A

D.stem-loops

39
Q

The reaction in DNA replication catalyzed by DNA ligase is:
A.Addition of new nucleotides to the leading strand
B.Addition of new nucleotide to the lagging strand
C.Formation of a phosphodiester bond between the 3’-OH of one Okazaki fragment and the 5’-phosphate of the next on the lagging strand
D.Base pairing of the template and the newly formed DNA strand

A

C.Formation of a phosphodiester bond between the 3’-OH of one Okazaki fragment and the 5’-phosphate of the next on the lagging strand

40
Q

Which of the following enzymes remove supercoiling in replicating DNA ahead of the replication fork?
A.DNA polymerases
B.Helicases
C.Primases
D.Topoisomerases

A

D.Topoisomerases

41
Q

A major difference between DNA replication in prokaryotes and eukaryotes is:
A.replication is conservative in prokaryotes
B.there is only one replication origin in prokaryotes
C.prokaryotes do not use Topoisomerase in the replication process
D.DNA amylase performs the function of DNA helicase in prokaryotes

A

B.there is only one replication origin in prokaryotes

42
Q

What happens after the DNA polymerase laying down a new DNA strand meed up with the RNA primer of a preceding Okazaki fragment?
A. the other strand is then replicated in the 3 to 5’ direction
B.DNA polymerase reverses direction and performs error checking
C.DNA ligase couples the two fragments together
D.the RNA primer is removed and is replaced by DNA

A

D.the RNA primer is removed and is replaced by DNA

43
Q

Why is an RNA primer necessary for DNA replication?
A. RNA primer is necessary for the activity of DNA ligase
B. RNA primer creates the 5’ and 3’ ends of the strand
C. DNA polymerase can only add nucleotides to RNA molecules
D. DNA polymerase can only add nucleotides to an existing strand with a free 3’ OH group

A

D. DNA polymerase can only add nucleotides to an existing strand with a free 3’ OH group

44
Q

Patients with no effective medications will develop which long term complication of Von Gierke’s disease:
A.Hyperuricemia
B.Hypercholesterolemia
C.Hepatic adenomas
D.Lactic acidosis

A

C.Hepatic adenomas

45
Q

Ribonucleotides consist of the following except:
A.Nitrogenous base
B.Ribose sugar
C.Deoxyribose sugar
D.Phosphate group

A

C.Deoxyribose sugar

46
Q

The product of DNA transcription is called:
A.Mature mRNA
B.Introns
C.Exons
D.Primary transcript

A

D.Primary transcript

47
Q

What forces hold the double-stranded DNA together?
A.Hydrophobic interactions
B.Covalent linkages
C.Dipole-dipole interactions
D. Hydrogen bonds

A

D. Hydrogen bonds (will be reviewed)

48
Q

Nucleic acids are polymers of nucleoside monophosphates. They consist of the following, except:
A.A pentose sugar in the furanose form
B.A phosphate group esterified to the sugar
C.A sulfide group ahached to the sugar
D.A nitrogenous base

A

C.A sulfide group ahached to the sugar

49
Q

All the following composes nucleosides, except:
A.Phosphate groups
B.Deoxyribose sugar
C.Ribose sugar
D.Purine bases

A

A.Phosphate group

50
Q

Which of the following has catalytic activity?
A. Nucleotides
B. Phospholipids
C. RNA
D. Phosphate group

A

C. RNA

51
Q

Which of the following statement regarding a double helical molecule of DNA is true?
A.All hydroxyl groups of pentoses are involved in linkages
B.Bases are perpendicular to the axis
C.Each strand is identical
D.Each strand is parallel

A

B.Bases are perpendicular to the axis

52
Q

Transient breaks made by _________ enable the strands of DNA to separate in the absence of he- lix rotation.
A. DNA topoisomerases
B.D-loops
C.5’–>3’ exonucleases
D.DNA gyrases

A

A. DNA topoisomerases

53
Q

Which of the following adds new nucleotides to a growing DNA chain?
A.DNA polymerase
B.DNA helicase
C.primase
D.RNA polymerase

A

A. DNA Polymerase

Biochemisty Main (29 decks)

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