What are those structures that appear as ‘beads-on-string’ in the chromosomes when viewed under electron microscope?

(1) Nucleotides

(2) Nucleosomes

(3) Base pairs

(4) Genes

Select the two statements out of the four (A - D) given below about lac operon.

(A) Glucose or galactose may bind with the repressor and inactivate it

(B) In the absence of lactose, the repressor binds with the operator region

(C) The z-gene codes for permease

(D) This was elucidated by Francois Jacob and Jacques Monod

The correct statements are

1. (B) and (C)

2. (A) and (C)

3. (B) and (D)

4. (A) and (B)

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

(1) degenerate

(2) ambiguous

(3) universal

(4) specific

Semi-conservative replication of DNA was first demonstrated in

(1) Drosophila melanogaster

(2) Escherichia coli

(3) Streptococcus pneumoniae

(4) Salmonella typhimurium

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

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’

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

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

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

(1) RNA polymerase

(2) ribosome

(3) transcription factor

(4) anticodon

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