DNA Structure and Replication

Q1: The 5' and 3' numbers are related to the

A length of the DNA strand

B carbon number in sugar

C the number of phosphates

D the base pair rule

Q2: DNA can be sequenced by the

A chemical method

B chain termination procedure

C both (a) and (b)

D physical method

Q3: A cesium chloride will separate DNA molecules by

A absorption

B resorption

C density

D adhesion

Q4: Okazaki fragments occur during

A transformation

B replication

C polymerase reaction

D synthesis

Q5: Telomeres are usually rich in which nucleotide?

A Adenine

B Guanine

C Thymine

D Cytosine

Q6: DNA replication takes place in which direction?

A 3' to 5'

B 5 'to 3'

C Randomly

D Vary from organism to organism

Q7: When DNA polymerase is in contact with guanine in the parental strand, what does it add to the growing daughter strand?

A Phosphate

B Cytosine

C Uracil

D Guanine

Q8: Taylor, Woods and Hughes labeled Vicia DNA by allowing new DNA synthesis in the presence of radioactive thymine. After DNA replication (S phase of the cell cycle), it was observed that

A only one chromatid of a chromosome was labeled

B both chromatids of a chromosome were labeled

C both (a) and (b)

D neither chromatid was labeled

Q9: Which of the following enzyme adds complementary bases during replication?

A Helicase

B Synthesase

C Replicase

D Polymerase

Q10: The overall conclusion of the Hershey-Chase experiment was that

A DNA was responsible for heredity

B proteins and DNA were responsible for heredity

C the ratio of Adenine to thymine was always the same

D phage DNA was similar to bacterial DNA

Q11: DNA gyrase in E. coli

A adds positive supercoils to chromosomal DNA

B can be inhibited with antibiotics

C is required only at the oriC site

D performs the same function as helicase in eukaryotes

Q12: Which is the largest among the followings?

A Nucleotide

B Nitrogenous base

C Phosphate

D Carbon

Q13: The accepted hypothesis for DNA replication is

A conservative theory

B dispersive theory

C semi-conservative theory

D evolutionary theory

Q14: The chromosomal DNA complexes with

A three types of histone as H1, H2A and H4

B five types of histone as H1, H2A, H2B, H3 and H4

C four types of histone as H1, H2A, H3 and H4

D two types of histone as H1 and H4

Q15: In DNA, guanine pairs with

A Adenine

B Cytosine

C Thymine

D Uracil

Q16: The most common liquid volumes in molecular biology are measured in

A ml

B μl

C nl

D 1

Q17: If one cell has AT contents 40%, what will be the percentage of Guanine residue?

A 60%

B 15%

C 30%

D Guanine residue can not be calculated

Q18: In DNA, there are

A five bases known as adenine, guanine, thymine, tryptophan and cytosine

B four bases known as adenine, guanine, thymine and cytosine

C three bases known as adenine, guanine and cytosine

D only two bases known as adenine and cytosine

Q19: Enzyme, responsible for proofreading base pairing is

A DNA polymerase

B Telomerase

C Primase

D DNA ligase

Q20: Which histone(s) are associated with the linker DNA of a nucleosome?

A Histone H1

B Histones H2A and H2B

C Histone H3

D Histone H4

Q21: Klenow fragment without free nucleotides exhibits

A exonuclease activity

B endonuclease activity

C nickase activity

D no activity

Q22: What is the approximate size (in kb) of the E. coli genome?

A 3000 kilobase

B 4500 kilobase

C 5500 kilobase

D 6500 kilobase

Q23: DNAs when charged, migrate in a gel towards the

A positive pole

B negative pole

C will not migrate

D none of these

Q24: Enzymes, responsible for unraveling short segments of DNA is

A DNA polymerase

B helicase

C DNA ligase

D primase

Q25: E.coli DNA polymerases II and III lack

A 5' → 3' exonuclease activity

B 5' → 3' endonuclease activity

C partially 5' → 3' exonuclease activity

D partially 5' → 3' endonuclease activity

Q26: The higher order structure of DNA shows symmetry, whereas the higher order structures of most proteins do not. Why isn't protein shape more regular like DNA?

A DNA has one main function in cells whereas proteins have many.

B The many different amino acid R groups on proteins confer many different shapes.

C Some S amino acids cause proteins to bend; others cause protein to flatten.

D All of the above

Q27: DNA helicase is used to

A unwind the double helix

B interact the double helix closely

C break a phosphodiester bond in DNA strand

D none of the above

Q28: Which of the following is incorrect?

A In DNA double helix, two strands of the DNA are bound with each other with the bases

B Adenine always pairs with thymine

C Guanine always pairs with the cytosine

D None of the above

Q29: Which DNA polymerase removes RNA primers in DNA synthesis?

A Polymerase I

B Polymerase II

C Polymerase III

D none of these

Q30: Messelsen and Stahl model of replication was called

A conservative replication

B semi-conservative replication

C dispersive replication

D Cri du Chat

Q31: In DNA double helix, the two DNA chains are held together by

A covalent bonds between the pair of bases

B hydrogen bonds between the pair of bases

C ionic bonds between the pair of bases

D none of the above

Q32: In the study of one experiment it was found that the value of Tm for DNA is = 40° C. If the cell has 20% GC at the above Tm, then what will be value of 'Tm' if the GC% increases to 60%?

A Remains same

B Increases

C Decreases

D Can not be compared

Q33: Which of the following would not contain DNA?

A Yeast

B Bacteria

C Glass crystals

D Mold

Q34: What is the range of melting point temperatures (Tm) for most DNA molecules?

A 50 to 60°C

B 60 to 80°C

C 70 to 90°C

D 80 to l00°C

Q35: What is the main damaging effect of UV radiation on DNA?

A Depurination

B Formation of thymine dimers

C Single strand break

D Dehydration

Q36: What is the only common methylation in the DNA of eukaryotes?

A Adenosine in GpA dinucleotides

B Guanosine in ApGpA trinucleotides

C Cytosine in CpG dinucleotides

D None of the above

Q37: Proteins involved in opening a replication bubble are

A DNA helicases

B single stranded binding proteins

C ligase

D DNA topoisomerase

Q38: The nucleosome consists of histone

A octamer and 146 bp of DNA

B tetramer and 146 bp of DNA

C hexamer and 146 bp of DNA

D none of the above

Q39: In sperm heads, DNA is particularly highly condensed and the histones are replaced with small basic protein called

A protamines

B purines

C pyrimidines

D all of the above

Q40: What bands will be observed in a cesium chloride gradient after two rounds of replication?

A One light, one medium and one heavy band

B One light and one medium band

C One medium band

D One medium and one heavy band


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