Question

cDNA stands for

• A. Circular DNA
• B. Complementary DNA
• C. Cytoplasmic DNA
• D. None of these

Answer 1

The correct option is B

Complementary DNA

The correct answer is option B.

Explanation of correct answer :-

1. cDNA is an abbreviation for complementary DNA.
2. cDNA is a DNA copy synthesized from mRNA by the action of reverse transcriptase.
3. cDNA only has coding sequences.
4. During transcription, both introns and exons are coded into messenger RNA (mRNA).
5. But, the introns are removed from mRNA to produce a mature mRNA by splicing the exons together which produces cDNA, containing only the protein-coding regions of the genome.
6. It is useful in bioinformatics and is also often used in gene cloning.

Explanation of incorrect answers :-

Option A

1. Circular DNA is a form of closed-loop DNA that has no ends like a circle.
2. This type of DNA is found in most prokaryotic cells.
3. Also, it is seen in organelles like chloroplasts and mitochondria.
4. The plasmid DNA is a classic example of extra-chromosomal circular DNA.

Option C

1. Cytoplasmic DNA is a small circular chromosome present outside the nucleus.
2. It is present within the cell organelles in the cytoplasm.

Final answer :cDNA stands for complementary DNA.