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.
One of the most frequently used techniques in DNA fingerprinting is
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → VNTR
Option (1) VNTR — Correct. VNTR stands for Variable Number of Tandem Repeats. The number of repeats differs from person to person, so a labelled VNTR probe gives a band pattern of its own for every individual. Only identical twins share the same pattern.
Option (2) SCAR — Incorrect. SCAR (Sequence Characterised Amplified Region) is a marker made by copying one known region of DNA with PCR. It is used mainly to tell plant varieties apart, not in DNA fingerprinting of people.
Option (3) SSCP — Incorrect. SSCP (Single Strand Conformation Polymorphism) finds small changes in one stretch of DNA from the way its single strand folds and moves in a gel. It is used to look for mutations, not to identify a person.
Option (4) AFLP — Incorrect. AFLP (Amplified Fragment Length Polymorphism) cuts DNA with restriction enzymes and copies some of the pieces with PCR. It is a marker used mostly in plant and microbe studies. It is not the technique NCERT describes for DNA fingerprinting.
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 – …
