bsc2010 ch 18 & 19 eukaryotic gene regulation

chromatin

inside of the nucleus, this structure is how DNA is stored

• beads on a string

• the string is DNA, the beads are histone proteins (the string coils around the histone proteins for structure)

histones

proteins found in chromatin that the DNA wraps around

nucleosomes

negatively charged DNA wrapped around positively charged histone proteins and can either be loose (euchromatin) or tight (heterochromatin)

• can be rearranged by sliding/removing histone groups

heterochromatin

tightly-packed histones in chromatin, usually aren’t expressed

• RNA polymerase cannot access when tightly-packed together

• closed chromatin, conformation, repression

DNA methylation

on the chromatin level, the addition of methyl groups to some cytosine bases in DNA → reduced transcription

genomic imprinting

methylation regulates expression of either maternal/paternal alleles at the start of development

euchromatin

in the chromatin, these genes are usually more expressed

• open chromatin, conformation, activation

histone acetylation

on the chromatin level, this is where the chromatin is loosened and transcription occurs more

transcription factors

on the transcription level, these are used to start transcription by activators binding to the enhancer to stimulate transcription

• some function as repressors, making a gene unable to be expressed

alternative RNA splicing

on the RNA processing level, depending on which RNA segments are treated as introns or exons, certain genes may/may not be present

mRNA regradation

on the translation level, mRNA has a lifespan and is often in the 3’ UTR

regulatory proteins

on the translation level, mRNA translation can be blocked by ______________, often binding to the 5’ UTR

proteasomes

on the post-translational level, a giant protein complex binds to tagged protein molecules to degrade them (protein degradation)

regulatory vs general transcription factors

general

• essential to any transcription for all genes

• mostly covers the basic groundwork genes

regulatory

• regulate transcription to specific genes

• mostly covers the specific genes