Molecular basis of inheritance
Read the following passage carefully and answer the given questions.
In bacteria, since the mRNA does not require any processing to become active, and also since transcription and translation take place in the same compartment, many times the translation can begin much before the mRNA is fully transcribed. Translation refers to the process of polymerisation of amino acids to form a polypeptide. The order and sequence of amino acids are defined by the sequence of bases in the mRNA. In lac operon, a polycistronic structural gene is regulated by a common promoter and regulatory genes. Such arrangement is very common in bacteria and is referred to as operon. In prokaryotes, control of the rate of transcriptional initiation is the predominant site for control of gene expression. In a transcription unit, the activity of RNA polymerase at a given promoter is in turn regulated by interaction with accessory proteins, which affect its ability to recognise start sites. These regulatory proteins can act both positively and negatively. DNA from every tissue of an individual show the same degree of polymorphism, they become very useful identification tool in forensic applications like DNA fingerprinting.
DNA fingerprinting involves identifying differences in specific regions in DNA sequence is -
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Repetitive DNA
(1) Coding DNA — Incorrect. The regions used in DNA fingerprinting normally do not code for any protein.
(2) Repetitive DNA — Correct. DNA fingerprinting finds the differences in some specific regions of the DNA sequence called repetitive DNA. In these regions, a small stretch of DNA is repeated many times. They are highly polymorphic, so they differ from person to person.
(3) Untranslated RNA — Incorrect. DNA fingerprinting compares DNA sequences. RNA is not used.
(4) Non-coding mRNA — Incorrect. The question is about DNA, and mRNA is the coding message copied from a gene.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
DNA Fingerprinting – …
