Control of Gene Expression Flashcards

Biological Sciences Bisc 011 with Brown at George Washington University - Foggy Bottom Campus

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By: Praveen Mahendran
Created: 2010-12-14
Size: 24 flashcards
Views: 18

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Histone modification

alteration of histones through various processes controls gene expressoni

histones

proteins around which the DNA is wrapped in nucleosomes

histone acetylation

acetyl groups (-COCH3) attached to lysines in histone tails

when aceyltated, positive charges are neutralized and histone tails no longer bind to neighboring nucleosomes

makes it easier for genes hidden by histones to be expressed?

methylation

addition of mehtyl groups (-CH3) promotes condensation of chromatin

hides genes

phosphorylation

addition ofphosphate group can unwind chromatin

reveals genes

histon code hypothesis

proposes that specific combinations of modifications, rather than the overall level of histone acetylation, determines chromatin configuration

heterochromatin and euchromatin

heterochromatin bound and condensed while euchromatin unwound due to acetylation and is able to be transcribed and produce RNA

heterochromatin must undergo demethylation to become euchromatin

transcriptional control

initiation of transcription is next major step of regulation after chromatin modification

in promoter itself, can be regions necessary for transcription factors to bind which determines whether or not RNA polymerase binds (TATA box has specific transcription factor

enhancer

segment of eukaryotic DNA containing multiple control elements

usually located far from gene whose transcription it regulates

requires activator proteins before binding to mediator proteins and general transcription factors

forms active transcription initiation complex on promoter

also DNA bending protein aids

heat shocked genes

DNA sequence called "heat shock element"

part of promoter of all genes

element involved in regulating multiple genes at once

coordinate control

single on-off switch that can control whole cluster of functionally related genes

post transcriptional control methods

RNA processing

alteration to CAP

3' polyA then transported to cytoplasm through nuclear pores and produces mRNA

alternative RNA splicing

introns spliced out of premRNA, possible to put exons together and create different mRNA which produces separate proteins

mRNA degradation

short life span allows pattern of protein synthesis to change

life span coded in untranslated region at 3' end

enzymatic shortening of poly-A tail can also trigger removal of 5' cap that leads to degradation

tachykinins

sensory neuropeptides. Ptachyk in neural, K tachyk in intestines, and thmal

only 1 premRNA made, when 2 proteins are produced one is p and one is K by only one is active and other degrades

translational control

untranslated regions regulate whether or not mRNA will be translated

regulatory proteins binds to untranslated region and block translation and prevent ribosomes from moving down

post translational control methods

protein folding

subunit interactions

covalent modification

deanimation

turnover

location

covalent modification

proteins need carbohydrate or phosphate (kinase) groups to activate them

deactivate by removing phosphate

deanimation

removal of amino acids, such as activation of insulin

ex.: preproinsulin-> proinsulin->insulin

turnover

time protein is around for

if cyclin were always/continously around, cell would never exit metaphase

important to destroy proteins

ubiquitin and proteasome, know these

ubiquitin

protein that is linked to proteins marking them for destruction

proteosome

finds proteins with ubiquitin attached and destroys them

signal recognition particle (SRP)

consists of proteins and a signal recognition RNA (srRNA)

protein can be funneled through lumen into ER

micro RNAs (miRNA)

mRNA that creates loops because it base pairs with itself, but then loops get cut off by enzyme and create double stranded RNA

dicer comes and snips off folded end

miRNA made by separating strands and forming miRNA protein complex that can block translation

binds with exact pairing

About this deck

By: Praveen Mahendran
Created: 2010-12-14
Size: 24 flashcards
Views: 18

About StudyBlue

“I have been getting MUCH better grades on all my tests for school. Flash cards, notes, and quizzes are great on here. Thanks!”
Kathy