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University of Science and Technology of Hanoi

Final Examination

Subject: Molecular Biology

Sheet: No of pages: 6

Intake: Academic year:

Date: Time: 90 mins

Important instructions

(according to lecturer’s decision)

1. Any document and communication devices

are not allowed in the examination venue.

2. …

Signatures

Pathway coordinator:

Lecturer (or Head of Subject) :

Dr. Kim Thị Phương Oanh

Question 1: In the Hershey-Chase experiment

a) DNA from parent bacteriophages appeared in progeny bacteriophages

b) Most of the phage DNA never entered the bacteria

c) More than three-fourths of the phage protein appeared in the progeny phagaes

d) DNA was labeled with sulfur

e) DNA formed the coat of the bacteriophages

Question 2: Linked genes:

a) must be immediately adjacent to one another on a chromosome

b) have alleles that assort independently of one another

c) never show crossing over

d) are on the same chromosome

e) always have multiple alleles

Question 3: Which of the following statements are true about double-stranded DNA?

a. A + C = T + G

b. A + G = C + T

c. A + T = G + C

d. A/G = C/T

e. A/G = T/C

Question 4: In the DNA of certain bacterial cells, 27% of the nucleotides are adenine. Which of the

following is true

a. The genome is 13.5% of guanosine

b. The genome is 27% of guanosine

c. The genome is 23% of guanosine

d. The genome is 46% of guanosine

Question 5: RNA molecules that exhibit catalytis activity are called

a. mRNAs

b. ribonucleases

c. ribosomes

d. ribozymes

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Question 6: Which of the following statements are NOT correct? Explain your answer

a. RNA contains deoxyribose

b. RNA contains uracil in place of adenine

c. RNA is typically single-stranded molecule

d. RNA chains fold back on themselves to form local regions of double helix similar to B-form

DNA

e. RNAs can form various stem-loop structures

f. Some RNAs are enzymes

Answers: True or False (correct the false statements)

Question 7: Which of the following statements are correct? Explain your answer

a. A DNA strand has a polarity because the bases contain hydrophilic amino groups

b. G-C base pairs are more stable than A-T base pairs

Answers: True or False (explain why?)

Question 8: The two strands of DNA double helix can be separated by heating. If you raised the

temperature of a solution containing the following three DNA molecules, in what order do you

suppose they would “melt”? Explain your answer.

a. 5’-GCGGGCCAGCCCGAGTGGGTAGCCCAGG-3’

3’-CGCCCGGTCGGGCTCACCCATCGGGTCC-5’

b. 5’-ATTATAAAATATTTAGATACTATATTTACAA-3’

3’-TAATATTTTATAAATCTATGATATAAATGTT-5’

c. 5’-AGAGCTAGATCGAT-3’

3’-TCTCGATCTAGCTA-5’

Answers:

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Question 9: For each of the terms in the left column, choose the best matching phase in the right

column

a) Replicator 1) The strand that is synthesized discontinuously during replication

b) Homologous

recombination

2) the protein that specifically recognizes a DNA element in the

replicator and activates the initiation of replication.

c) Operon 3) regulatory DNA sequence to which regulatory proteins bind,

influencing the rate of transcription of a structural gene that can be many

thousands of base pairs away

d) Promoter 4) Short length of DNA produced on the lagging strand during DNA

replication

e) Operator 5) Nucleotide sequence in DNA to which RNA polymerase binds to begin

transcription

f) Semiconservative

replication

6) the entire set of cis-acting DNA sequences that is sufficient to direct

the initiation of DNA replication.

g) Okazaki fragments 7) Short region of DNA in a bacterial chromosome that controls the

transcription of an adjacent gene

h) Initiator 8) The strand of the double helix separate and act as template for new

strands

i) lagging strand 9) Genetic exchange between a pair of homologous DNA sequences,

typically those located on two copies of the same chromosome

j) Enhancer 10) In a bacterial chromosome, a group of contiguous genes that are

transcribed into a single mRNA molecule

1 2 3 4 5 6 7 8 9 10

Question 10: Which statements about nucleosome are NOT true? Explain your answer

a. Nucleosomes consist of DNA wound around a histone core

b. The nucleosomes have a core of 8 histone proteins (two molecules each of histone H2A, H2B,

H3, H4)

c. The core DNA is approximately 60 base pair length

d. Core histones are positively-charged proteins

e. H2A and H2B histones can form a tetramer.

f. Histones have an abundance of two amino acids: glycine and alanine

Answers: True or False (correct the false statements)

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Question 11: DNA ligase does which of the following

a. catalyzes DNA replication

b. joins Okazaki fragments to the high molecular weight DNA on the lagging strand

c. requires dNTPs

d. removes RNA primer

e. unwinds double helical DNA

Question 12: A gene encoding one of the proteins involved in DNA replication has been inactivated

by a mutation in a cell. In the absence of this protein the cell attempts to replicate its DNA for the very

last time. What DNA products would be generated in each case if the following protein were missing?

a. Primase

b. DNA polymerase

c. Sliding clamp for DNA polymerase

d. DNA ligase

Answers:

Question 13: MutS, MutL and MutH are proteins that involve in

a. DNA mismatch repair system

b. Photoreactivation

c. Base excision repair pathway

d. Nucleotide excision repair pathway

e. Double-strand break (DSB) repair pathway

Question 14: Which of the following statement is NOT correct? Explain your answer.

a. Glycosylase is an enzyme that repair replication errors in E. coli.

b. Methyltransferase is an enzyme that removes the methyl group from the methylated base O6-

methylguanine by transferring it to one of its own cysteine residues.

Answers: True or False (explain why?)

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Question 15: The sequence of bases located prior to the gene (along the DNA strand), to which a

complex of RNA polymerase and sigma factors attaches itself to initiate transcription is called:

a. initiator

b. promoter

c. replicator

d. enhancer

e. exon

f. intron

Question 16: Complete the following sentences with the name of proteins which involve in

transcription in eukaryotes

a. …………………………………………transcribes the mRNA.

b. …………………………………………transcribes the large ribosomal RNA precursor gene.

c. …………………………………………transcribes tRNA genes, some small nuclear genes, and

the 5S rRNA gene.

d. …………………………………………cleave the RNA at the intron-exon borders and

covalently link the exons together.

e. …………………………………………use ATP as a precursor and adds about 200 adenines to

the RNA’s 3’-end

Question 17: Which of the following is NOT involved in the processing of mRNA precursor in

eukaryotic cells

a. Capping of the 5’ end

b. Addition of poly A

c. Excision of introns

d. Splicing of exons

e. Transport of the pre-mRNA to the cytoplasm

Question 18: Which of the following statements are correct? Explain your answers (If it is false,

explain why?)

a. Because the two strands of DNA are complementary, the mRNA of a given gene can be

synthesized using either strand as a template

b. An mRNA may contain the sequence ATTGACCCCGGTCAA

Answers: True or False (explain why?)

Question 19: Which of the following do NOT need a primer in order to function?

a. DNA pol I

b. DNA pol II

c. DNA pol III

d. RNA polymerase

e. Reverse transcriptase

f. Telomerase

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Question 20: In the transcriptional control, a repressor protein binds to

a. an enhancer

b. a promoter

c. an operator

d. a ribosome-binding site

e. TATA box

f. initiator

Question 21: Eukaryotes use 80S ribosomes which consist of:

a. a (small) 30S and a (large) 50S subunit

b. a (small) 40S and a (large) 60S subunit

c. a (small) 30S and a (large) 40S subunit

d. a (small) 40S and a (large) 50S subunit

e. a (small) 30S and a (large) 60S subunit

Question 22: tRNA molecules are linked to their respective amino acids by enzymes called:

a. glycosylase

b. aminoacyl-tRNA synthetase

c. guanylyl transferase

d. methyl transferase

Question 23: The bonds that form between the anticodon of a tRNA molecule and the three

nucleotides of a codon in mRNA are …………….”. Complete this sentence with each of the following

options and explain why the resulting statements are correct or incorrect.

a. Covalent bonds formed by GTP hydrolysis

b. Hydrogen bonds that form when the tRNA is at the A-site

c. Broken by the translocation of the ribosome along the mRNA

Answers: Correct or Incorrect (explain why?)

Question 24: Every polypeptide chain formed in translation starts with the amino acid:

a. Alanine

b. Methionine

c. Lysine

d. Serine

e. Arginine

f. Glycine

Question 25: Which of the following is NOT a stop codon ?

a. UAA

b. GUA

c. UAG

d. UGA