BIO SCI 93 Chapter Notes - Chapter 18: Start Codon, Intron, Polyadenylation

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 93
• Professor: Justin Shaffer

Document Summary

Differential gene expression is the expression of different genes by cells with the same genome. Function of any cell depends on the appropriate set of genes being expressed. Cell must locate right genes at the right time. When gene expression proceeds abnormally, serious imbalances and diseases can arise. Histone acetylation promotes transcription by opening up the chromatin structure. N-terminus or histone tails protrude outwards from the nucleosome, accessible to various modifying enzymes that catalyze the addition or removal of specific chemical groups. Dna methylation is the process in which enzymes methylate certain bases in the dna, usually cytosine. Individual genes usually more heavily methylated in cells are not expressed. Removal of extra methyl groups can turn on some of these genes. Once methylated, genes usually stay that way through successive cell divisions in a given individual. Inheritance of traits transmitted by mechanisms not involving the nucleotide sequence itself is called epigenetic inheritance.