Term
Where are DNA regulatory sequences of genes found?
What do these DNA regulatory sequences bind?
The combination of regulatory protein and DNA results in what? |
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Definition
found in promoter or w/in the gene=cis acting elements
Gene regulatory proteins=trans-acting element
(high specificity)
GENETIC SWITCH-gene transcription initiation on or off |
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Term
DNA recognition sequences are usually what?
DNA recognition sequences are often distortable or bendable which means what? |
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Definition
pallindromic-create 1/2 sites for transcription factor to bind as DIMER
AT-rich or have irregularities that can be specifically recognized by transcription factors |
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Term
DNA binding domains includes?
What is found in DNA binding proteins? |
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Definition
helix-turn-helix, alpha helix inserts into the major groove
Zn-finger to interact w/sequential repeats of DNA recognition sequence so increased strength of DNA-protein interaction |
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Term
NEGATIVE REGULATION
What are the roles of repressors? |
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Definition
bind DNA and blocks transcription
(ligand can activate or inactivate) |
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Term
POSITIVE REG. of Transcription
What is the role of activator? |
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Definition
it binds DNA and stimulates transcription
(ligand can bind and activate/inactivate) |
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Term
What does trp operon contain?
How does concentration of typtophan affect gene expression?
How does the it act as inhibitory ligand?
By binding ligand to operator sequence is gene off and how? |
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Definition
genes for tryptophan
at high level of trp turns gene off
acts as inhibitory ligand by binding repressor and causing conformational change so recognition helix is in proper orientation to interact w/operator sequence--turning off gene
turns gene off and prevents RNA polymerase binding |
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Term
How is trp operon expression regulated?
At high levels of trp how is transcription terminated?
Does rate of translation affect mRNA structure? |
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Definition
attenuation-concurrent transcri/translation
mRNA folds into terminator sequence and no trp syn occurs
yes by change in transcription rate |
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Term
When does lac repressor repress lac operon expression?
What does CAP activate? |
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Definition
when lactose is absent
genes that allow for use of alternate sugars like lactos when gluc levels are low |
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Term
What is the role of enhancers?
How is this achieved?
What is the role of gene activator?
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Definition
facilitate the interaction of activator proteins at enhancer w/initiation proteins and RNA poly at the promoter
DNA looping with DNA acting as "tether"
to interact w/ general transcription factors to fac assembly(stabilize initiation complex) |
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Term
What is role of histone acetylases?
What is role of histone deacetylases?
Repressive chromatin remodeling? |
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Definition
loosen contact btwn DNA and histones to allow transcription to occur
to remove activating acetyl groups from histones making transcriptionally inactive
convert euchromatin to heterochromatin |
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Term
| Where does changes in gene expression typically occur? |
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Definition
| DOWNSTREAM of signal transduction pthwy by CRE bound to CREB or steriod hormone bound to Zn-finger which activates transcription |
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Term
What is RNA editing?
If the transcript is unaltered what protein does it produce?
If a C deaminated to U, a Gln is converted to a stop codon so what protein is formed?
Does expression of ApoB100 and ApoB48 use the same gene? Where does RNA editing take place? |
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Definition
a form of gene regulation where nucleotides are enzymatically changed AFTER transcription is complete
ApoB100
ApoB48
yes same gene, produced in tissues where needed |
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Term
RNA editing takes place in?
Splicing takes place in?
Is RNA editing differential splicing?
Which one uses chemical modification to bases in RNA?
Which one involves breaking and resealing phosphodiester backbone?
Which is more common in Prokaryotes?
What are two mechanisms for RNA editing? |
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Definition
cytosol
nucleus
NOT differential splicing
RNA editing
splicing
RNA editing
1)enzymatic deamination
2) insertion |
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Term
What does RISC do?
How is siRNA formed?
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Definition
cleaves dsRNA to act as a protective mech. by destroying the invading mRNA
dsRNA activates enzyme DICER which cleaves dsRNA to form siRNA which can now hybridize w/target mRNA |
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