Prokaryotic and Eukaryotic gene regulation Flashcards
cis-regulating factors
are DNA sequences on the same DNA strand as the gene they regulate
trans-regulating factors
are proteins that bind to cis-element DNA sequences
what are the different proteins involved in prokaryotic gene regulation and what do they do?
there are activators and repressors that control the rate of RNA synthesis (transcription)
what do activators do and what type of control do they have?
they recruit RNA polymerase and increase transcription with a positive control
what are repressors and what type of control do they have?
they block RNA polymerase and inhibit transcription with a negative control
what is the role of small effector molecules in transcriptional regulation, and the 3 different types
they exert the effects by binding to activator or repressor.
inducers, corepressors, inhibitors
what do inducers do
they either:
- bind to activators and cause them to bind to DNA
- bind to repressors and prevent them from binding to DNA
what do corepressors do
they bind to activators and cause them to bind to DNA
what do inhibitors do
bind to activators and prevent them from binding to DNA
what is an operon
a regulatory unit containing multiple genes under the control of a single promoter
the parts of lac operon
promoter, CAP site, operator, protein-encoding genes ( lacZ, lacY, lacA), terminator
encodes for a repressor protein
Lacl
why cant RNA polymerase reach the promoter when the repressor is bound
repressor prevents the RNA polymerase to continue transcription because of its lack of small effector molecules binding to repressor
what are eukaryotic transcription factors
they are proteins that aid in regulating RNA polymerase’s ability to transcribe a gene
general transcription factors are required for?
binding of RNA polymerase to the core promoter
what regulates the rate of transcription in eukaryotic gene regulation
regulatory transcription factors
Difference between TFIID and Activator proteins
TFIID are general transcription factors that bind to TATA box and recruits RNA polymerase
Activator proteins aid TFIID in recruiting TATA box, RNA polymerase, and interacts with coactivators
what do mediator proteins do and what are the two types
they mediate the interaction between transcription factors and RNA polymerase.
Theres:
Transcriptional activators
transcriptional repressors
what are regulatory/control elements for
they recognize sequence patterns located near core promoter and these proteins bind to these elements, impacting transcription.
difference between up and down regulation
up-regulation are usually with activators that increase the rate of transcription and bind to enhancer elements .
down-regulation involves repressors that decrease rate of transcription and binds to silencer elements
3 major epigenetic mechanisms
- reversible mod. of DNA by add/removal of methyl groups
- alt. of chromatin by add/removal of chemical groups to histone proteins
- regulation of gene expression by small, noncoding RNA molecules
plays a role in gene regulation and is associated with decreased gene expression
DNA methylation-addition or removal of methyl groups to or from bases in DNA
how can methylation repress transcription
by preventing transcription factors from binding with the DNA
major epigenetic mechanisms in eukaryotes
DNA methylation and histone modification
Histone modifications alter
chromatin conformation and protein interactions with the DNA strand
3 ways to modify histones
acetylation, methylation, and phosphorylation
which histone modification makes genes on nucleosomes available for transcription and is reversible
histone acetylation
chromatin domains
heterochromatin-highly condensed (not acetylated)
euchromatin-less condensed (acetylated)
remodeling complexes may alter nucleosome structure by:
- altering the contacts between DNA around the nucleosome
- altering the path of the DNA around the nucleosome
- altering the structure of the nucleosome core itself
transcriptional activation involves changes in
nucleosome locations, nucleosome composition, and histone modifications
why do we need to regulate gene expression?
response to environment, metabolism, cell division, development in eukaryotes
