Final answer:
The scientist has constructed a cDNA library by isolating mRNA from kidney cells and synthesizing DNA from it, which is then inserted into vectors. This library represents only the expressed genes of the cells from which the mRNA was isolated.
Step-by-step explanation:
Constructing a cDNA Library
When a scientist isolates mRNA from a cell and uses reverse transcriptase (RT) to synthesize DNA, which is then inserted into vectors, they are creating a cDNA library. This type of library includes only the expressed genes of a specific cell type, excluding the introns and regulatory sequences not usually translated into protein. Each cDNA library represents a unique transcriptome, reflecting the mRNA transcripts present in the cells at the time of isolation and provides insights into which genes are actively being expressed. This is crucial for understanding gene expression patterns and functions in different cell types or under various conditions.
No other options, such as genomic, protein, or antibody libraries, fit this description. A genomic library contains all the sequences from an organism's DNA, including non-coding regions. In contrast, a protein library or an antibody library would contain a collection of proteins or antibodies, not copies of DNA derived from mRNA. Therefore, the library constructed in this scenario is a cDNA library, which is an invaluable tool for molecular biology research.
1) cDNA library. This library type is specifically constructed from the expressed genes of a given cell using mRNA as a template for DNA synthesis.