Question

A piece of nucleic acid used to find out a gene, by forming hybrid with it, is called as

• A. cDNA
• B. DNA probe
• C. Sticky end
• D. Blunt end

Answer 1

Answer: (B)

DNA probe

cDNA (complementary DNA) is double-stranded DNA synthesised from an mRNA template. This conversion is carried out by the enzyme reverse transcriptase. This technique is often used to clone eukaryotic genes in the prokaryotes. The cloned eukaryotic cDNAs lack introns and other non-coding sequences present in the corresponding genome.

A DNA probe is a radioactively labelled DNA segment of variable length used to detect the presence of target nucleotide sequences in the DNA sample. The DNA probe is complementary to the target nucleotide sequences and thus, forms a hybrid with the sequence.

Sticky ends refers to any two complementary ends of a molecule that can anneal. In case of DNA, the ssDNA ends with complementary base sequence to facilitate their base pairing to form a circular DNA.

Most of the restriction enzymes that introduce staggered cut in DNA at their restriction site create sticky ends. The blunt ends are the base paired ends of DNA.

Thus, the correct answer is option B.