Refer to the given figure and answer the following questions. (a) Identify the labelled part A and mention its function. (b) What does B and C represent? (c) Briefly describe the process shown in the given figure.

Refer to the given figure and answer the following questions.

(a) Identify the labelled part A and mention its function.

(b) What does B and C represent? 

(c) Briefly describe the process shown in the given figure.

Answer.  (a) Labelled part A represents the enzyme reverse transcriptase. Reverse transcriptase is used to synthesise DNA or complementary DNA by using mRNA as template.

(b) The labelled part B represents the separated singlestranded complementary DNA after the RNA-DNA complex is treated with alkaline phosphatase enzyme. The labelled part C is the newly formed double-stranded cDNA. (c) This diagram represents the synthesis of  complementary DNA or cDNA from RNA. With the help of the enzyme reverse transcriptase, an RNA-DNA complex is formed from RNA (usually mRNA) where RNA acts as the template. The mRNA in the RNA-DNA complex is digested in the presence of alkaline phosphatase enzyme. A cDNA is formed on the separated single-stranded DNA template with the help of the enzyme DNA polymerase.