Eukaryotic Gene Expression (Regulation of Chromatin Structure (Changes in…
Eukaryotic Gene Expression
Mechanisms of Post-Transcriptional Regulation
A process where different mRNA molecules are produced by the same primary RNA transcript. Some of the exons are spliced out like they are introns
Regulation of Chromatin Structure
Histone acetylation or the attachment of acetyl groups to certain amino acids promotes transcription by opening up the chromatin structure.
Methylation is the presence of methyl groups on DNA bases that inhibits transcription by condensing chromatin structure
Changes in chromatin structure can be passed down through generations from epigenetic inheritance
DNA modification = irreversible, chromatin modification = reversible
traits that are not necessarily involved in the nucleotide sequence itself
Structure of chromatin allows DNA to be packed tightly into nucleus and allows for regulation of gene expression.
Regulation of Transcription Initiation
General transcription factors are essential for transcription of all protein coding genes
can bind to TATA box or other proteins (transcription factors and RNA Polymerase II.
Enhancers and specific transcription factors
distal control elements meaning they are far from the promoter are called enhancers. Rate of gene expression can be greatly increased or decreased by enhancers.
Silencing: repressors recruit proteins that remove acetyl groups from histones, leading to reduced transcription
Coordinately controlled genes: genes that are clustered into an operon that is regulated by a promoter and transcribed into an mRNA molecule.
Can occur with genes from different chromosomes. These genes are expressed together, and the proteins are produced at the same time.
Initiation of Translation and mRNA Degradation
Initiation of translation can be blocked by proteins that bind to certain sequences. This occurs in the UTR at the 5′ or 3′ end. It prevents the attachment of ribosomes.
Protein Processing and Degradation
Proteins can be activated or deactivated by adding phosphate groups, and proteins destined for the surface of animal cells will get sugars attached.