unit 6 regulation of gene expression

operon

a group of genes that operate together and have related function

what is regulation of gene expression in prokaryotes?

- clusters of genes (operon) regulated - cytoplasm - no histones - no introns - regulation only at the transcriptional level

what is regulation of gene expression in eukaryotes?

- individual genes regulated - nucleus and cytoplasm - DNA is wrapped around histones - introns are present - regulation at all levels

operator of operon

on/off switch

repressors

prevent RNA polymerase from binding to the DNA< preventing transcription

repressible operon

an operon under negative control. It is usually "on" but can be turned "off". - anabolic reaction

inducible operon

an operon under positive control. It is usually "off" but can be turned "on". - catabolic reaction

alternative splicing

different mRNA molecules are reproduced from the same primary transcript depending on which exons are used

what is post-transcriptional regulation?

??

what is regulating chromatin structure?

??

what is regulating transcription initiation?

??

what is regulation of gene expression?

Includes a wide variety range of mechanisms that are used by cells to increase or decrease the production of a specific gene products (protein or RNA) and is formally termed gene regulation

histone acetylation

acetyl groups are added to histones which presents them from binding to DNA as tightly, making room for proteins to bind for transcription

genes of operon

code for proteins

activators

help RNA polymerase bind to the DNA< increasing transcription

initiation of translation

if the ribosome does not form or mRNA cannot attach, translation does not occur

protein processing and degradation

many proteins need to be modified to become active, may be modified by the addition of ubiquitin, which triggers proteasomes to break down the protein

DNA methylation

methyl groups can attach to DNA bases, preventing transcription

mRNA degradation

nuclease enzymes break down mRNA, lifespan of mRNA varies

what are the parts of the operon?

promoter, operator, genes

promoter of operon

where RNA polymerase attaches