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 genomic library made from brain?

Key Concepts

Genomic Libraries

Genomic libraries are collections of DNA fragments that represent the entire genome of an organism. These libraries are created by cloning DNA into vectors, allowing researchers to isolate and study specific genes. The composition of a genomic library can vary based on the tissue source, as different tissues express different sets of genes.

Gene Expression and Tissue Specificity

Gene expression refers to the process by which information from a gene is used to synthesize functional gene products, typically proteins. Tissue specificity indicates that certain genes, like myostatin, are expressed predominantly in specific tissues, such as muscle cells. This means that a genomic library derived from a non-expressing tissue, like the brain, is less likely to contain clones of genes that are not expressed in that tissue.

Cloning and Screening

Cloning involves inserting a DNA fragment into a vector to replicate it within a host organism, often bacteria. Screening is the process of identifying clones that contain the desired DNA sequence. In the context of a genomic library from the brain, the likelihood of finding a clone for myostatin is low, as the gene is not expressed in brain tissue, leading to fewer or no clones representing it.