What is the template strand used to create cDNA in reverse transcription?

The correct answer is messenger RNA, which serves as the template strand in the process of reverse transcription to create complementary DNA (cDNA). During reverse transcription, the enzyme reverse transcriptase synthesizes cDNA from the mRNA template. This process is crucial because cDNA is often used in molecular biology for various applications, such as cloning, gene expression analysis, and constructing cDNA libraries.

In this scenario, mRNA contains the coding information that is transcribed from DNA, and it represents the expressed genes in a cell. The reverse transcription process allows researchers to convert this mRNA back into DNA, facilitating further studies and manipulations of the genetic material.

The other options, such as transfer RNA and ribosomal RNA, do not function as templates for the synthesis of cDNA. Transfer RNA plays a critical role in translating mRNA into proteins by transporting amino acids to the ribosome, while ribosomal RNA is a key component of ribosomes, essential for protein synthesis but not directly involved in the reverse transcription process. Proteins themselves are the end products of gene expression and do not serve as templates for cDNA synthesis.