Molecular Basis of Inheritance

The one aspect which is not a salient feature of genetic code, is its being –

1. Specific
2. Degenerate
3. Ambiguous
4. Universal

Select the two correct statements out of the four (A–D) statements given below about lac operon. The correct statements are :

1. B and D
2. A and B
3. B and C
4. A and C

Whose experiments cracked the DNA and discovered unequivocally that a genetic code is a "triplet"?

1. Nirenberg and Matthaei
2. Morgan and Sturtevant
3. Hershey and Chase
4. Beadle and Tatum

Semi-conservative replication of DNA was first demonstrated in:

1. Drosophila melanogaster
2. Streptococcus pneumoniae
3. Salmonella typhimurium
4. Escherichia coli

Removal of introns and joining the exons in a defined order in a transcription unit is called:

1. Transformation
2. Capping
3. Splicing
4. Tailing

What is not true for genetic code?

1. It is nearly universal
2. A codon in mRNA is read in a noncontiguous fashion
3. It is degenerate
4. It is unambiguous

In the DNA molecule:

1. the total amount of purine nucleotides and pyrimidine nucleotides is not always equal
2. there are two strands which run antiparallel one in 5' 3' direction and other in 3' 5'
3. there are two strands which run parallel in the 5' 3' direction
4. the proportion of adenine in relation to thymine varies with the organism

Which one of the following pairs of nitrogenous bases of nucleic acids is wrongly matched with the category mentioned against it?

1. Thymine, Uracil — Pyrimidines
2. Guanine, Adenine — Purines
3. Uracil, Cytosine — Pyrimidines
4. Adenine, Thymine — Purines

Which one of the following pairs of codons is correctly matched with their function or the signal for the particular amino acid?

1. UUA, UCA — Leucine
2. AUG, ACG — Start/Methionine
3. UAG, UGA — Stop
4. GUU, GCU — Alanine

One turn of the helix in a B-form DNA is approximately -

1. 20 nm
2. 3.4 nm
3. 2 nm
4. 0.34 nm