chapter 25: control of gene expression - eukaryotes Flashcards
gene expression control in eukaryotes
- chromatin remodeling
- transcription factors
- splicing
- mRNA stability
- translation
- post-translational mods
nucleosome
8 histones + DNA
- organization determined by histone types and modifications to tail regions
3D chromatin architecture
determined by histone tail modifications (like acetylation)
chromatin arrangement
determines which regions of DNA can be accessed by transcription factors and enzymes
directly methylated DNA is a ___ modification
repressive
epigenetic markers can be
put directly on DNA
DNA regions of transcription factors
enhancers, promoter, insulator, promoter-proximal, silencer
core promoter
binding site for GTFs where RNA pol 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 up or downstream of coding region
activators
- bind to enhancer regions and recruit HATs to decondense chromatin
- this exposes core promoter + promoter - proximal elements as well as other distal regulatory elements
mediator protein
- binds activating TFs to loop DNA and maintain open chromatin
- binds GTFs which call over and bind RNA pol II to start transcription
insulators
stop the spread of heterochromatin
preaxial polydactyly
point mutation in enhancer binding site leads to ectopic or abnormal expresssion of a gene; causes extra fingers to develop
enhancer
inceases transcription
silencer
decreases transcription
insulator
stops heterochromatin from spreading and silencing gene; maintains transcription
mRNA stability + translation control
- mRNAs degrade mRNA transcripts making gene expression changes more dynamic
- miRNAs can also block translation by binding to mRNAs
micro RNAs can control translation in 2 ways
- translational repression
- mRNA cleavage
microRNAs
- transcribed from genome
- coup up with a protein
- can be markers of disease
