Molecular Biology and Genetics MCQs

Question 1

During transcription,

Accepted Answer

Both DNA gyrase and DNA topoisomearse I introduce negative supercoils

Answer

DNA gyrase introduces negative supercoils and DNA topoisomerase I removes negative supercoils

Answer

DNA topoisomerase I introduces negative supercoils and DNA gyrase removes negative supercoils

Answer

Both DNA gyrase and DNA topoisomearse I remove negative supercoils

Question 2

What will be the binding status of regulatory proteins in lac operon when concentrations of both lactose and glucose are very low in the culture medium?

Accepted Answer

Both the repressor and cAMP-CAP complex remain bound to their respective binding sites

Answer

Only the repressor remains bound to the operator

Answer

Only the cyclic AMP-Catabolic Activator Protein (cAMP-CAP) complex remains bound to the CAP binding site

Answer

Neither the repressor nor cAMP-CAP complex remain bound to their respective binding sites

Question 3

The 5' ends of the mature forms of the prokaryotic mRNAs and tRNAs are

Accepted Answer

A triphosphate group in mRNAs and a monophosphate group in tRNAs

Answer

Triphosphate groups in both mRNAs and tRNAs

Answer

Monophosphate groups in both mRNAs and tRNAs

Answer

A monophosphate group in mRNAs and a triphosphate group in tRNAs

Question 4

Nuclease-hypersensitive sites in the chromosomes are sites that appear to be

Accepted Answer

Nucleosome free

Answer

H2 and H4 histone free

Answer

H1 and H2 histone free

Answer

H3 and H4 histone free

Question 5

How many different protein sequences of 100 residues can be generated using 20 standard amino acids?

Accepted Answer

20100

Answer

10020

Answer

100 × 20

Answer

100! × 20!

Question 6

The G + C content of bacteriophage M13 double stranded DNA is 68%. What would you expect the G + C content of its mRNA?

Accepted Answer

About 68%

Answer

About 34%

Answer

About 32%

Answer

About 86%

Question 7

Efficient expression of a heterologous protein product is influenced by

Accepted Answer

All of the above

Answer

Transcriptional efficiency

Answer

Copy number of the plasmid

Answer

Codon bias

Question 8

The 4-amino or 4-keto group of pyrimidine bases is located in the

Accepted Answer

Major groove of the double stranded DNA

Answer

Minor groove of the double stranded DNA

Answer

Minor groove of the B form DNA but not the A form DNA

Answer

Major groove of the B form DNA but not the A form DNA

Question 9

Which one of the following modifications is common to both protein and DNA?

Accepted Answer

Methylation

Answer

SUMOylation

Answer

Nitrosylation

Answer

Ubiquitination