Nucleic Acids

Q1: Which of the following is not found in membranes?

A Glycoproteins

B Glycolipids

C Nucleic acids

D Phospholipids

ANS:C - Nucleic acids

No answer description is available.

Q2: Because DNA is a highly charged polyanion, its stability to heat denaturation

A does not depend on hydrophobic interactions

B increases with increasing salt

C is independent of G - C content

D decreases with increasing salt

ANS:B - increases with increasing salt

Increase in salt concentration mask the charge on both strands of DNA. Thus making them very stable and the resultant repulsion force will be minimized. As a result the stability of DNA increases with increase in salt concentration and require higher temperature than in absence of salt.

Q3: In gel electrophoresis, what fragments will move most quickly through a gel?

A Large fragments

B Small fragments

C Large genome

D None of these

ANS:A - Large fragments

Smaller fragments will have an easier time passing through gel than larger fragments which will allow it to move through more smoothly than the larger fragments.

Q4: The unfavourable free energy associated with not satisfying a hydrogen bond after formation of the double helix is approximately

A 10 kJ/mol

B 20 kJ/mol

C 25 kJ/mol

D 30 kJ/mol

ANS:B - 20 kJ/mol

No answer description is available.

Q5: The sugar in RNA is __________ , the sugar in DNA is __________

A deoxyribose, ribose

B ribose, deoxyribose

C ribose, phosphate

D ribose, uracil

ANS:B - ribose, deoxyribose

Deoxy means deficiency.

Firstly, both DNA and RNA Are made up of the ribose sugar. But what differentiate DNA from RNA Is nothing but the presence or absence of OH at carbon #2.

*DNA have a deficiency in OH WHILE the RNA have no deficiency of OH.

Q6: A five carbon sugar lacking a hydrogen at the number 2 carbon is found in

A DNA

B RNA

C mRNA

D rDNA

ANS:A - DNA

No answer description is available.

Q7: A purine with an amine (NH2) group on the 6th carbon is

A adenine

B cytosine

C thymine

D guanine

ANS:A - adenine

Guanine will have Oxygen on its 6th carbon atom. Adenine has NH group on its 6th carbon atom so Adenine is correct.

Q8: Nucleic acids can be analyzed experimentally by their

A molecular weight

B absorption of visible light

C absorption of uv light

D none of these

ANS:C - absorption of uv light

No answer description is available.

Q9: The glycosidic bonds in DNA and RNA

A connect the sugar to the base

B can be hydrolyzed by OH- ion

C stabilize Watson-Crick H-bonds

D are free to rotate over about 180°

ANS:A - connect the sugar to the base

A glycosidic bond is any bond linking a suger to any other atom and/or molecule.

Q10: A nucleotide consists of

A a sugar, a base and a phosphate

B a sugar and a phosphate

C paired bases

D a sugar, a base and three phosphates

ANS:A - a sugar, a base and a phosphate

No answer description is available.

Q11: Which of the following is a purine?

A Cytosine

B Adenine

C Thymine

D Uracil

ANS:B - Adenine

No answer description is available.

Q12: Nucleoside is a pyrimidine or purine base

A covalently bonded to a sugar

B ionically bonded to a sugar

C hydrogen bonded to a sugar

D none of the above

ANS:A - covalently bonded to a sugar

Nitrogen base is bound to the sugar by the means of glycosidic bond and the glycosidic bond is a covalent bond so either pyrimidine or purine are bound to the sugar by the means of covalently bound glycosidic bond.

Q13: Thymidine

A can participate in hydrophobic interactions due to its methyl group

B is replaced by uracil in RNA

C normally forms two hydrogen bonds with adenosine

D all of the above

ANS:D - all of the above

No answer description is available.

Q14: Which of the following is found on RNA but not DNA?

A Uracil

B Deoxyribose

C Phosphate

D Adenine

ANS:A - Uracil

No answer description is available.

Q15: The most stabilizing force for nucleic acids is

A hydrogen bonds

B electrostatic bond

C Van der Waals

D conformational entropy

ANS:C - Van der Waals

No answer description is available.

Q16: Which pyrimidine base contains an amino group at carbon 4?

A Cytosine

B Thymine

C Uracil

D Adenine

ANS:A - Cytosine

Guanine is not a Pyrimidine so cytosine has the amino group at 4 carbon atom.

Q17: Nucleotide bases and aromatic amino acids absorb light respectively at

A 280 and 260 nm

B 260 and 280 nm

C 270 and 280 nm

D 260 and 270 nm

ANS:B - 260 and 280 nm

No answer description is available.



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