Regulation of Transcription Flashcards
four types of DNA binding regulatory proteins
helix turn helix
zinc fingers
leucine zippers
helix loop helix
these proteins regulate genes involved in development
helix turn helix
these proteins are steroid hormone receptors
zinc finger motif
these proteins regulate cell division genes
leucine zipper
these proteins regulate immune system genes
helix loop helix
examples of DNA binding domains
homeodomains
how do DNA binding domains interact with the major groove of DNA
H-bonds
salt-bridges
hydrophobic interactions
two characteristics of DNA binding domains
rich in alpha helices
can bind to promoters and enhancer sequences
have an acidic patch that allows interaction with other transcription factors
activation domain
what can activation domains bind to
other transcription factors
RNA polymerase II
activators
genes are not transcribed unless an activator is present
positive control
positive control that turns genes on
activation
positive control that turns genes off
deactivation
genes are always transcribed unless a repressor is present
negative control
negative control that turns genes off
repression
negative control that turns genes on
derepression
a unit of genetic function consisting of groups of genes with related functions where a single promoter and operator serve to control the expression of all genes in that unit together
operons
where to operons primarily occur
in prokaryotes and nematodes
an inducible operon where transcription is stimulated in the presence of lactose
lac operon
a repressible operon where transcription is inhibited in the presence of tryptophan
trp operon
lactose is made up of
galactose and glucose
what form of lactose binds to the lac operon repressor
allolactose
regulatory genes for the lac operon code for
repressor protein
CAP
the lac repressor exhibits what kind of motif
helix turn helix
what three enzymes are coded for in the lac operon
Beta-galactosidase
permease
transacetylase
in conjuction with cAMP, serves as an indicator of glucose availability
CAP
when there is no glucose and there is lactose
increase in cAMP and binding to CAP
50x increase in transcription of lac genes
when there is glucose and lactose present
decreased cAMP and no binding to CAP
weak transcription
when there is glucose and no lactose present
decreased cAMP and no binding to CAP
lac repressor present and no transcription
how is trp operon different from lac operon
the presence of tryptophan causes the inhibition of the operon instead of its activation
affect the configuration of chromatin and gene expression
chemical modification of histone tails
how are histone tails modified
attachement of acetyl group to lysines
protein recruited to keep histones deacetylated
HDAC
activator protein binding recruits this protein which acetylates histones
HAT
histone modification that prevents transcription
methylation at lysines and arginines residues
what is the epigenetic regulation of histones in DNA
addition of methyl groups to cytosines of DNA
limits body weight and cell proliferation
H19
insulin like growth factor
IGF2
on the maternal chromosome and enhancer drives expression of ____ and an insulator protein blocks ____expression
H19 and IGF2
on paternal chromosome, methylation inactivates the ICR and block the ____ expression, enhancer drives ____expression
H19 and IGF2
if H19 is mutated or missing this disease develops
angelman syndrome
if IGF2 is mutated or missing this disease develops
prader-willi syndrome
what binds to the TATA box
transcription factors
what are close to the promoter
proximal control elements
may be far away from a gene or even in an intron
enhancers
what binds to enhancers
activators
bind to silencer region of the DNA to inhibit expression of a particular gene
repressors
describe the process of mRNA degradation
miRNA folds onto itself
dicer protein claves miRNA into smaller fragments
miRNA binds to protein complex
miRNA protein complex binds with mRNA
mRNA is degraded or translation is blocked
