Question

A scientist isolates mRNA from a specific type of cell found in the kidney. The mRNA is then converted to DNA using RT and the DNA fragments are inserted into appropriate vectors. What kind of library has the scientist constructed?

1) Genomic library
2) cDNA library
3) Protein library
4) Antibody library

Answer 1

The scientist has constructed a cDNA library, which involves isolating mRNA from cells, converting it into cDNA, and inserting the fragments into vectors, allowing the study of expressed genes.

Step-by-step explanation:

The scientist has constructed a cDNA library. This type of library is created by isolating mRNA from cells, which represents all the transcripts or the cell's transcriptome at the time of isolation. The mRNA is then converted to DNA through the action of the enzyme reverse transcriptase, creating complementary DNA or cDNA. Finally, these cDNA fragments are inserted into suitable vectors, which can then be used to analyze and sequence the DNA encoding for proteins expressed by the cells in question.

A cDNA library is crucial for studying just the genes that are active (expressed) in a particular cell type or under certain conditions, without including introns and regulatory sequences found in genomic DNA. The cDNA library thus reflects the transcriptome of the cell, giving insight into which genes are operational at the time of mRNA extraction.