BIO exam 3 module 9

Module 9 - gene regulation and development

gene regulation

encompasses the ways in which cells control gene expression

• Occurs via modifications of:

  • DNA/ chromatin

  • RNA transcription

  • RNA processing

epigenetic effects

produce phenotypes variation w/out changing the DNA sequences of a gene

• changes in the manner in which DNA is packaged

chromatin modification

chromatin remodeling is accomplished through modifications if the histone tails

Enhancer

short region of DNA (50-1500 bp) that can be bound by activator proteins to increase the likelihood that transcription of a particular gene will occur

Activator

protein that binds to an enhancer and promotes the transcription of a particular gene

Promoter

DNA sequence that provides a secure initial binding site for RNA polymerase and the general transcription factors that recruit RNA polymerase

• located just upstream of a particular gene (ex. TATA box)

• location on the lac operon where RNA polymerase binds

General (basal) transcription factor

protein that binds to a promoter and facilitates the recruitment of RNA polymerase

• (ex: TATA box binding protein)

Mediator

multi-protein complex that facilitates transcription by interacting with transcription factors and RNA polymerase. Mammals may have up to 26 subunits in one complex

Positive regulation

CRP-cAMP and RNA polymerase complexes are bound to the Lac Operon allowing transcription to proceed

• if the activator does not bind - transcription does not occur

Negative regulation

repressor protein is bound to repressor binding site and thus transcription does not occur

• transcription can occur if the native site allows the RNA polymerase complex to be recruited

Operator (lacO)

site on the Lac Operon where a repressor protein binds

CRP-cAMP complex

component of the Lac Operon that is active when glucose is low