Foundations of Biology Exam 4: Gene Expression Control II- Eukaryotes

nucleosome

8 histones + DNA

heterochromatin

closed, tight-packed, DNA hard to access by regulatory proteins; genes cannot be expressed

euchromatin

open, loosely packed, DNA easy to access by regulatory proteins; genes get expressed

acetyl group

partially negatively charged group added to a histone tail to create a open chromatin structure

methyl group

partially positively charged group added to a histone tail to create a closed chromatin structure

epigenetics

chromosome duplication involves duplicating the entire chromatin structure, so the DNA and chromatin-associated proteins (histones, etc) are all duplicated

proteins that regulate gene expression

- activators

- repressors

- transcription factors

DNA regions that regulate gene expression

- enhancers

- promoter

- insulator

- promoter-proximal

- silencer

core promoter

binding site for GTFs and where RNA polymerase II binds

promoter proximal elements

binding site for activator/repressor proteins (TFs)

distal regulatory regions

DNA sequences farther away from protein coding DNA sequence, can be upstream or downstream of coding region; where TFs bind

enhancer

a distal regulatory region that increases transcription

silencer

distal regulatory region that decreases transcription

insulator

distal regulatory region that stops heterochromatin from spreading and silencing gene, maintains translation; makes sure euchromatin stay open by binding together to form loops

distal regulatory elements

________ _________ _________ facilitate chromatin remodeling

distal regulatory regions

- enhancer

- silencer

- insulator

mediator protein complex

binds multiple activator TFs to loop open DNA and bind GTFs to call over RNA pol II to start transcription

heterochromatin

insulators stop the spread of _______ ______

TAD

formed by loops of chromatin fibers, anchored at their base by the protein cohesin and other DNA-binding proteins; form larger chromatin compartments, which can either promote or repress gene transcription

microRNA

degrade mRNA transcripts making gene expression changes more dynamic; can block translation by binding to mRNAs; in cytosol; can also be a marker of disease