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

(1) 20 nm

(2) 0.34 nm

(3) 3.4 nm

(4) 2 nm

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

(1) t-RNA

(2) m-RNA

(3) c-DNA

(4) r-RNA

Differentiation of organs and tissues in a developing organism, is associated with:

(1) developmental mutations

(2) differential expression of genes

(3) lethal mutations

(4) deletion of gens

During transcription RNA polymerase holoenzyme binds to a gene promoter and assumes a saddle-like structure. What is it’s DNA-binding sequence?

(1) TTAA

(2) AATT

(3) CACC

(4) TATA

Molecular basis of organ differentiation depends on the modulation in transcription by:

(1) RNA polymerase

(2) ribosome

(3) transcription factor

(4) anticodon

Haploids are more suitable for mutation studies than the diploids. This is because

(1) haploids are reproductively more stable than diploids

(2) mutagenes penetrate in haploids more effectively than is diploids

(3) haploids are more abundant in nature than diploids

(4) all mutations, whether dominant or recessive are expressed in haploids

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

1. GUU, GCU – Alanine

2. UAG, UGA – Stop

3. AUG, ACG – Start/methionine

4. UUA, UCA – Leucine

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 parallel in the 5’ → 3’direction

(3) the proportion of adenine in relation to thymine varies with the organism

(4) there are two strands, which run antiparallel-one in 5’ → 3’ direction and other in 3’ → 5’

What is not true for genetic code?

1. A codon in mRNA is read in a non-contiguous fashion

2. It is nearly universal

3. It is degenerate

4. It is unambiguous

Semi-conservative replication of DNA was first demonstrated in

(1) Drosophila melanogaster

(2) Escherichia coli

(3) Streptococcus pneumoniae

(4) Salmonella typhimurium