Molecular Basis of Inheritance

(b) Translation is the synthesis of protein synthesis occurs over ribosomes which are also referred to as protein factories.

(b) The tautomer forms of nitrogen bases are imino-tautomer instead of amino group (e.g. cytosine, adenine) or enol instead of the keto group (e.g. thymine, guanine).

Tautomers are organic compounds that are interconvertible by a chemical reaction called tautomerisation.

The concept of tautomers that are interconvertible by tautomerisations is called tautomerism.

(d) Codons are 64 in number.

Out of this, 61 codes for amino acids.

Each codon possesses 3 bases, each of which can undergo transition and transversion.

$(61 \times 3^{2}=549)$

(d) The phenomenon of making DNA over RNA genome through enzyme reverse transcriptase is called reverse transcription or teminism.

(a) Protein synthesis involves initiation, elongation and termination.

Transcription is the process of synthesis of RNA from DNA.

(a) DNA gyrase participates in the supercoiling of DNA helix during replication.

(c) The parts of a gene, which become part of mRNA and code for different regions of the proteins are called exons.

(b) Termination codons (triplet) are the stop signals which when encountered cause termination of polypeptide synthesis.

The termination codons are UAA, UAG and UGA.

(c) Replication of DNA is discontinuous over the lagging strand i.e., over this strand only small stretches of DNA are built due to opposite running of DNA template.

The small stretches of DNA are called Okazaki fragments.

(d) X-ray crystallography is a technique to study the binding of specific proteins to regulatory DNA.

X-ray crystallography or single-crystal X-ray diffraction is an analytical technique which uses the diffraction pattern produced by bombarding a single crystal with X-rays to solve the crystal structure.