cDNA is formed by

• A. DNA dependent DNA polymerase
• B. RNA dependent DNA polymerase
• C. DNA dependent RNA polymerase
• D. DNA ligase

cDNA, or complementary DNA, is synthesized from RNA templates. The correct answer to your question is:

Correct Answer

B. RNA dependent DNA polymerase

Explanation

RNA dependent DNA polymerase, also known as reverse transcriptase, is the enzyme responsible for creating cDNA from an RNA strand. This process is crucial in molecular biology, especially for cloning and studying gene expression.

Other Options

• A. DNA dependent DNA polymerase: This enzyme synthesizes DNA from a DNA template.
• C. DNA dependent RNA polymerase: This enzyme synthesizes RNA from a DNA template.
• D. DNA ligase: This enzyme joins DNA fragments together but does not synthesize DNA.

Understanding these enzymes helps clarify their specific roles in genetic processes.