Using the genomic libraries in Problem 4, you wish to clone the human gene encoding myostatin, which is expressed only in muscle cells. How frequently will a clone representing myostatin be found in the cDNA library made from brain?

Key Concepts

cDNA Library

A cDNA library is a collection of complementary DNA (cDNA) sequences synthesized from messenger RNA (mRNA) transcripts. It represents the expressed genes in a specific tissue at a given time. Since myostatin is expressed only in muscle cells, a cDNA library derived from brain tissue would contain little to no myostatin cDNA, making it unlikely to find a clone representing this gene.

Gene Expression

Gene expression refers to the process by which information from a gene is used to synthesize functional gene products, typically proteins. Different genes are expressed in different tissues, depending on the cell type and its function. Myostatin is specifically expressed in muscle cells, which means it is not expressed in brain cells, further reducing the chances of finding its clone in a brain-derived cDNA library.

Cloning

Cloning in genetics involves creating copies of a specific DNA sequence or gene. This process often utilizes vectors to insert the target DNA into host cells for replication. In the context of the question, cloning the myostatin gene from a cDNA library made from brain tissue would be ineffective, as the absence of myostatin expression in that tissue means the gene is unlikely to be present in the library.