gene regulation

gene regulation

controlling which genes are expressed

why not just express all genes all the time? (3)

protein synthesis needs energy, specialized cells need different gene expressions, some proteins can be harmful when not needed

gene regulation in prokaryotes changes most based on if ___ happens or not

transcription

operon

transcriptional unit in prokaryotes

transcriptional unit

stretch of DNA that can all be made into 1 mRNA

3 parts of operon

promoter, operator, structural genes

are regulator genes part of the operon?

no

regulator genes are vital to determining if _____ happens

transcription

operons are present in what biomolecule?

double-stranded DNA

the operator and promoter sequences ____ with each other

overlap

repressor function

turns off transcription when bound to operator by preventing RNA polymerase from binding to promoter

promoter

DNA sequence where RNA polymerase binds, determines if transcription starts

operator

DNA sequence where repressors bind, overlaps with promoter

structural genes

encode non-regulatory proteins

polycistronic

many genes on same mRNA

are prokaryotes polycistronic?

yes

are eukaryotes polycistronic?

no

how many genes are on each mRNA strand in eukaryotes?

1

regulatory proteins determine if…

other genes are expressed

where are regulatory proteins encoded and by what type of genes?

outside operon by regulator genes

are regulatory proteins made all the time?

yes

regulatory proteins only ___ under certain conditions

bind

different operons have different repressor _____

proteins

what does the Trp operon do?

makes tryptophan

when there is NO tryptophan around, is a repressor bound or unbound to the operator?

unbound

when there IS tryptophan around, is a repressor bound or unbound to the operator?

bound

feedback inhibition in gene regulation

end product of metabolic pathway turns off gene expression that makes product

what does the Lac operon do?

regulates proteins that break down lactose

when there is NO lactose around, is a repressor bound or unbound to the operator?

bound

when there IS lactose around, is a repressor bound or unbound to the operator?

unbound

Trp repressor is normally _____, and Trp presence _____ it

inactive, activates

Lac repressor is normally _____, and Lac presence _____ it

active, inactivates

feedback inhibition is present in which operon?

Trp

transcription factors

regulatory proteins that increase or decrease transcription

in eukaryotes, ___ transcription factors regulate each gene

many

5 methods of eukaryotic gene regulation

chromatin modification, transcriptional control, post-transcriptional control, translational control, post-translational control

different _____ can result in different gene _____

conditions, expressions

eukaryotes have ___ levels of gene regulation than prokaryotes

more

chromatin modification

some parts of DNA stay condensed, so those genes are not expressed

transcriptional control

does transcription happen or not

how is post-transcriptional control carried out?

alternative splicing

where does post-transcriptional control/modification take place?

nucleus

translational control depends on if ___ is around and if it will go on to make ___

mRNA, protein

post-translational control depends on…

how long protein lasts