Regulation in Eukaryotes Flashcards
6 different levels of gene regulation in eukaryotes
transcription
mRNA processing
transport
mRNA functional regulation
translation rates modulated
protein modification
why are cis and trans factors fundamental components of gene regulation
cis is on the same chromosome as the gene it regulates(promoters are only cis)
trans regulates transcription by binding to a different chromosome
They determine level and timing of transcription
2 major mechanisms of epigenetic genes
methylation: reversible
histone modification/chromatin remodeling: alter accessibility of genes for transcription
what 3 mechanisms covalently modify N-terminal region of histone tails in amino acids
acetylation(activates)
phosphorylation(activates)
methylation(repress or activate)
what does chemical modification of histones make genes accessible or inaccessible for
transcription
function of insulators
compartmentalize gene regulation
function of locus control regions
relocation of chromosome territories
function of enhancers
aggregation of multiple proteins form large complexes.
can be cis or trans
function of silencers
bind regulatory proteins
can be cis or trans
function of enhancesomes
-direct DNA bending into loops
-TFs bound to promoters or enhancers
-allow factors to interact with preinitiation complex
can be cis or trans
what are the two functional regions of transcription factors?
what do they bind to?
DNA-binding domain: binds to DNA sequences in regulatory site
Trans-activating: binds to RNA polymerase at promoter
what is a TAD
topologically associated domain: guides regulatory elements to their cognate promoters
what is F syndrome caused by? what does F syndrome cause?
inversion involving TAD in front of WNT6 gene causing syndactyly of first and second finger
what is the second common regulation
post transcriptional regulation
does alternative splicing occur in prokaryotes
no
what(when highly expressed) enhances genes and promotes alternative splicing?
what exons are excluded and which are retained?
MYC protein
causes exon 9 exclusion and exon 10 retention
(this is opposite from what happens in healthy/normal cells)
roles of DICER and RISC
DICER: cleaves dsRNA into 21 nt fragments-siRNA and miRNA
RISC: combine with siRNA and miRNA to cleave specific mRNA and remove on of dsRNA
what molecular gene regulation mechanism causes white stripes in purple or red petunias
co-suppression
what did Fire and Mello use to discover gene silencing by double stranded RNA
RNA carrying code for a muscle protein was injected into worm C. elegans
name atleast one incRNA other than XIST
HOTAIR: positional identity
TERC: telomere elongation
COOLAIR: control flowering locus in plants
specific features of eukaryotic genomes
-many specialized cells
-many developmental stages
-complex interaction(large genomes)
-many chromosomes
-chromatin
-DNA–>protein
what are the DNA binding domains
helix-turn-helix
zinc-finger
helix-loop-helix
leucine zipper
what helps control mRNA stability
translation products
regulation of a- and B-tubulins
-first 4 AA form recognition element
-if free tubulins are present in cytoplasm they bind to recognition element
-tubulin binding to 4-AA element triggers activity of RNase that degrades tubulin mRNA and stops tubulin translation
