Read the passage carefully and answer the given questions.
DNA fingerprinting
Polymorphism in DNA sequence is the basis of genetic mapping of the human genome as well as of DNA fingerprinting. DNA fingerprinting involves identification of differences in some specific regions in the DNA sequence called repetitive DNA. It works on the principle of polymorphisms in DNA sequences. The repetitive DNA are separated from bulk genomic DNA. The bulk DNA forms a major peak and the other small peaks are referred to as satellite DNA. These repetitive/satellite DNA sequences show a high degree of polymorphisms and form the basis of DNA fingerprinting.
Variable Number of Tandem Repeats are -
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Satellite DNA
The name Variable Number of Tandem Repeats (VNTR) tells what the DNA is like. “Tandem repeats” means a short DNA sequence repeated many times, one copy right after the other. “Variable number” means that the number of these copies differs from person to person.
Option (1) Satellite DNA — Correct. Repetitive DNA separates from the bulk DNA as small peaks, and these peaks are called satellite DNA. VNTRs are one class of satellite DNA, the mini-satellites. Their copy number varies so much that each person gets his own band pattern.
Option (2) Silent DNA — Incorrect. “Silent DNA” is a loose name sometimes used for DNA that does not code for any protein. It is not the class into which VNTRs are placed; NCERT calls them satellite DNA.
Option (3) SNPs — Incorrect. SNPs are single nucleotide polymorphisms, places where people differ in just one base. The Human Genome Project found about 1.4 million of them. A change in a single base is not a repeat of a sequence.
Option (4) ESTs — Incorrect. ESTs are Expressed Sequence Tags. In the Human Genome Project they were used to identify all the genes that are expressed as RNA. They mark genes, not repeated sequences.
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 – …
