NEET Botany Molecular Basis of Inheritance Questions Solved


Describe the process of transcription in a bacterium.                       5 mark

Initiation process of transcription in bacteria. 

1. In bacteria, the transcriptin of all the three types of RNA (mRNA, tRNA, rRNA) is catalysed by single DNA-dependent enzyme called the RNA polymerase.

2. RNA polymerase bends transiently with sigma factor (initiation factor).

3. Promoter region is the start single, short sequence of nitrogenous bases present in DNA. RNA polymerase along with sigma factor binds to it and initiate the process of transcription.

Elongation process of transcription in bacteria.

1. RNA polymerase binds itself to the promoter region.

2. One of the two strands of DNA function as template.

3. RNA polymerase helps in opening of helix and continuous elongation. The two strands of DNA uncoil progressively from the site of polymerase binding.

4.RNA polymerase uses nucleotide triphosphate as substrate and polymerises nucleotides in a template, following the rule of complementarity.

Termination process of transcription in bacteria.

1. When the RNA polymerase reaches to the terminator region, mRNA gets separated from DNA.

2. RNA polymerase is transiently associated with terminator factor (Rho factor -ρ) and removed from the transcription unit.

    5 mark

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