Molecular Basis of Inheritance · Question 121

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

One gene-one enzyme hypothesis was postulated by -

1. A. Garrod
2. Hershey and Chase
3. Beadle and Tatum
4. R. Franklin

Antiparallel strands of a DNA molecule means that-

1. The phosphate groups at the start of two DNA strands are in opposite position (pole)
2. One strand turns anti-clockwise
3. One strand turns clockwise
4. The phosphate groups of two DNA strands, at their ends, share the same position

Which antibiotic inhibits interaction between tRNA and mRNA during bacterial protein synthesis?

1. Neomycin
2. Erythromycin
3. Tetracycline
4. Streptomycin

Amino acid sequence, in protein synthesis is decided by the sequence of -

1. cDNA
2. mRNA
3. tRNA
4. rRNA

E. coli cells with a mutated z gene of the lac operon cannot grow in medium containing only lactose as the source of energy because -

1. They cannot transport lactose from the medium into the cell
2. They cannot synthesize functional -galactosidase
3. In the presence of glucose, E. coli cells do not utilize lactose
4. The lac operon is constitutively active in these cells