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Exam 3 - Last Lecture
Adv. Molecular Bio
32
Biology
Graduate
12/04/2019

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Term
how do you discover whether a cis element is necessary or not for transcription?
Definition
make mutations and/or deletions & see which sequence prevents transcription (or prevents repression of transcription if you're messing with a down-regulator)
Term
how do you discover whether something is sufficient for transcription?
Definition
move cis element into a gene that is not normally transcribed & see if you can induce transcription
Term
where do you find the core promoter?
Definition
cis element very close to the start site of the gene
Term
job of the core promoter
Definition
position RNA polymerase at the transcription start site so that it is poised to initiate transcription at the right place with the right "friends" that enable it to do so
Term
enhancers
Definition
amplify the signal of transcription
Term
silencer
Definition
dampens the signal of transcription
Term
what proteins do enhancers & silencers bind to do their jobs?
Definition
transcription factors
Term
how were distal enhancers found?
Definition
they did ChIP (chromatin immunoprecipitate) & found out that transcription factor that binds very far away is necessary for transcription --> then co-IP that transcription factor & figure out which part of the DNA sequence they bind to (discovered that these sequences are found very far away from transcription start site)
Term
basal factors
Definition
trans-acting factors that every gene uses
Term
do genes have specific trans-acting factors?
Definition
yes
Term
RNA polymerase is made up of ______ enzymes
Definition
10 (many subunits)
Term
cleft of RNA polymerase
Definition
active binding site where it does its stuff
Term
GTFII works with ______ to do transcription
Definition
RNA polymerase
Term
GTF II D subunit
Definition
TATA binding protein subunit
Term
GTF II B subunit
Definition
sticks its nose into the active site of the RNA polymerase & helps position the active site near the transcription start site
Term
GTF II A subunit
Definition
binds near B & D & stabilizes them
Term
GTF II E subunit
Definition
recruits H to the complex
Term
GTF II H subunit
Definition
contains a DNA helicase
Term
5 possible roles for transcription factors
Definition
1. bind DNA
2. scaffolding proteins
3. enzymes
4. remodelers
5. co-activators
Term
2 possible results of PTM modifications that can happen on histones
Definition
1. make binding sites for transcription factors
2. weaken nucleosomes
Term
Why are there many more unique scaffolding & DNA binding proteins than there are co-activators?
Definition
they need to be more specific
Term
3 major types of histones
Definition
1. H1
2. H2a/H2b
3. H3/H4
Term
why are tails on the histones what are modified by modifying transcription factors?
Definition
accessible outside of the nucleosome
Term
is DNA available for transcription while in the nucleosome formation?
Definition
no
Term
what is the implication that transcription factors can be "friendly"?
Definition
you can get a bunch binding within a very short stretch of nucleotides (only 50!)
Term
layout of nucleosomes along the DNA
Definition
about 147 base pairs of DNA wrapped around histone (forming the nucleosome) followed by 50-80 base pairs between that nucleosome & the next one
Term
what is the highly structured order of nucleosomes along the DNA?
Definition
package together in solenoids with nucleosome-free regions between them
Term
how do you get transcription cis elements that are so far away to come together?
Definition
you form a loop!
Term
how does the cell know which nucleosome to remove?
Definition
what is unique is the DNA sequence being hidden
Term
pioneer transcription factors
Definition
bind to DNA on surface of nucleosome & recruit remodelers/histone modifiers
Term
what is the protein that forms a ring around the two DNA strands in the loop to help stabilize it to bring the various enhancers together?
Definition
condensin
Term
_______ attaches to double-stranded DNA but reads single-stranded DNA
Definition
RNA polymerase
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