Lecture 16 Flashcards
Regulatory sequences (enhancers):
cis-acting elements
A eukaryotic gene is regulated by many
regulatory elements and proteins
Expression of genes are governed by the gene control region:
promoter and regulatory sequences
binds to a gene’s regulatory sequences to determine where and when transcription will initiate
Specific DNA binding proteins
Specific DNA binding proteins can be either
repressors or activators
Regulatory elements/sequences can be found – either upstream or downstream from the promoter
tens of thousands of base pairs
Genes are – in the area of chromatin condensation…by histone –
Genes are inactivated in the area of chromatin condensation…by histone deacetylation
Genes can be – in areas where the chromatin is decondensed…histone –
Genes can be expressed in areas where the chromatin is decondensed…histone acetylation
can bind to regulatory elements (enhancers) near or far away from the promoter region.
activators
An activator can influence– of chromatin to promote RNA polymerase to bind or stabilize the preinitiation complex.
decondensation
Repressors: binds to control elements (–) to promote condensation; inhibit transcription.
silencer
located within 100 – 200 bp upstream of the
start site; can be cell-type specific
Promoter-proximal element (PE):
Enhancers are – which can stimulate transcription from up to 50 kb from the start site
DNA sequences
enhancers Can be located upstream or downstream from the start site, even within an –
intron
enhancers are often cell-type specific
• Can increase transcription up to
1,000X
n both prokaryotes and eukaryotes, transcriptional activators and repressors are –, composed of distinct functional domains…can function without the other
modular proteins
Activation/repression domain: interacts with other proteins or .
another subunit of the same protein
A specific gene is only expressed when a cell contains – of the above regulatory proteins.
correct combination
Eukaryotic gene regulatory proteins ofter assemble into – on DNA
complexes
– lead to different complexes, which lead to different activities.
Different DNA binding sequences
T/F: A protein can be in either an activator or repressor complex
true
Enhancers are composed of one or more binding sites for –
regulatory proteins
Activators interact with other proteins (i.e. co-activator or mediator complex) to bring in and stabilize transcription machinery, causing the –
intervening DNA to loop out
– is the molecular bridge between activators and RNA Pol II
Mediator
Several DNA-bound activators can interact with a –
single mediator complex
The mediator complex is a type of – which are intermediary proteins that assist the transcription activators to stimulate initiation of transcription
co-activator
Subunits of a mediator can bind to –, activation domain of various activator proteins, and histone acetylation activity
RNA pol II
Transcription is controlled by a variety of – that interact with specific DNA sequences.
regulatory proteins/transcription factors
Whereas Mediator and general transcription factors are the same for all RNA pol II, – relative to the promoter differs for each gene
transcribed genes, transcription regulators, and locations of their binding sites
Patterns of – can be inherited
DNA methylation
methylated DNA is correlated with – regions of the chromosomes
inactive
The most commonly methylated sequence in DNA
CG (cytosine iss methylated)
DNA sequences that prevent regulatory proteins from influencing distant genes
insulators
T/F: Alternative RNA splicing can produce different forms of a protein from the same gene
true
38,016 different proteins could be made from this particular gene-
Dscam
The phosphorylation of – slows down protein synthesis
eIF2
IRES (internal ribosome entry site) provide opportunities for– control
translation
IRES-dependent translation bypasses the need for 5’ cap and its initiation translation factor - .
eIF4E
The IRES-dependent mechanism seen mainly in –.
viruses
mRNA can be
translated, stored in stress granules, degraded in P-bodies
after gradual poly-A shortening –>
- continued 3’ to 5’ degradation
2. recapping followed by rapid 5’ to 3’ degradtion
– of each mRNA is important for its half life
specific 3’ UTR sequence
competition between mRNA translation and decay because
deadenylase that shortens the poly-A tail in the 3’ to 5’ direction also associates with 5’ cap
mRNA degradation through microRNA (miRNA) involves
RISC
transcriptional silencing
during mRNA degradation, – in conjunction with other complements of RISC, initially associates with both strands of miRNA and then cleaves and discards one of them
argonaute
argonaute cleaves the target mRNA, causing its –
rapid degradation
