If an E.coli with heavy DNA allow to grow for 80 minutes in a culture medium of 14 NH 4

Cl, then what would be the proportion of heavy,light and hybrid densities DNA molecule

respectively?

1. 1/16 : 1/16 : 14/16

2. 0/16 : 14/16 : 2/16

3. 1/16 : 14/16 : 1/16

4. 1/8 : 2/8 : 6/8

Alec Jeffrey’s name is associated with

a. DNA sequencing

b. DNA fingerprinting

c. RNA sequencing

d. Gene cloning

Which of the following RNA polymerase catalyses the formation of transfer RNA in eukaryotes?

(1) RNA polymerase I                        

(2) RNA polymerase II

(3) RNA polymerase I and II              

(4) RNA polymerase III

Out of 64 codons how many of them code for amino acids?

(1) 64                            

(2) 20                            

(3) 61                            

(4) 32

Circular DNA is found in:
(1) Viruses

(2) Bacteria, chloroplast and mitochondria

(3) Chloroplast and mitochondria alone

(4) All of these

If in a DNA molecule cytosine is 18%, the percentage of adenine would be:

(a) 18%                (b) 32%                (c) 36%                (d) 64%

Isotopes used in proving semiconservative replication of DNA were:

(1) ¹⁴N ¹⁴C            

(2) ¹⁴N ¹⁵N            

(3) ¹⁴N ³¹P             

(4) ¹⁴C ³¹P

Bacterial nucleoid has:

(1) One single-stranded DNA            

(2) One double-stranded DNA

(3) Two single-stranded DNA             

(4) Many double-stranded DNAs

Imagine an error occurring during DNA replication in a cell, so that where there is supposed to be a T in one of the genes there is instead a G. What effect will this probably have on the cell?
(1) The amino acid sequence of one of its kinds of proteins will be completely changed

(2) An amino acid will be missing from each of its kinds of proteins

(3) One of its kinds of proteins might contain an incorrect amino acid

(4) An amino acid will be missing from one of its kinds of proteins.

A sequence of pictures of polypeptide synthesis shows a ribosome holding two transfer RNAs. One tRNA has a polypeptide chain attached to it; the other tRNA has a single amino acid attached to it. What does the next picture show?
(1) The polypeptide chain moves over and bonds to the single amino acid

(2) The tRNA with the amino acid leaves the ribosome

(3) The amino acid moves over and bonds to the polypeptide chain

(4) The tRNA with the polypeptide chain leaves the ribosome