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101 Cards in this Set
- Front
- Back
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Regulation of gene expression is crucial for:
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-Responses to extracellular stimiuli (both multicellular and unicellular organisms)
-Defining cell types (multicellular organisms) |
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What enzyme transcribes DNA into RNA?
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RNA polymerase
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What does the enzyme RNA polymerase do?
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It transcribes DNA into RNA
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In prokaryotic transcription what is the promoter?
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Region of DNA that indicates transcription start site.
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In prokaryotic transcription what is the region of DNA that indicates the transcription start site called?
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promoter
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In prokaryotic transcription what binds to the promoter?
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sigma factor and the RNA polymerase
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In prokaryotic transcription what is the RNA polymerase holoenzyme?
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The complete complex needed for transcription, including DNA, sigma factor and RNA polymerase
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In prokaryotic transcription after the RNA polymerase holoenzyme binds to the DNA what is the first thing it does?
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It unwinds the DNA
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In prokaryotic transcription after the RNA polymerase unwinds the DNA what happens?
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Transcription begins
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In prokaryotic transcription what happens once ~10 nucleotides are synthesized?
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sigma factor is released
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In prokaryotic transcription when is the sigma factor released?
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once ~10 nucleotides are synthesized
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In prokaryotic transcription after the sigma factor is released what happens?
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transcription elongation followed by transcription termination
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What does the TBP subunit due?
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Recognizes TATA box
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What recognizes the TATA box?
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TBP subunit
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What do TAF subunits do?
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recognizes other DNA sequences near the transcription start point; regulates DNA-binding by TBP
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What recognizes other DNA sequences near the transcription start point and regulates DNA-binding by TBP?
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TAF subunits
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What does TFIIB do?
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recognizes BRE element in promoter; accurately positions RNA polymerase at the start site of transcription
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What recognizes BRE element in promoters and accurately positions RNA polymerase at the start site of transcription
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TFIIB
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What does TFIIF do?
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stabilizes RNA polymerase interaction with TBP and TFIIB; helps attract TFIIE and TFIIH
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What stabilizes RNA polymerase interaction with TBP and TFIIB; helps attract TFIIE and TFIIH?
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TFIIF
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What does TFIIE do?
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attracts and regulates TFIIH
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What attracts and regulates TFIIH?
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TFIIE
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What does TFIIH do?
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unwinds DNa at the transcription start point, phosphorylates Ser5 of the RNA polymerase CTD; releases RNA polymerase from the promoter
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What unwinds DNa at the transcription start point, phosphorylates Ser5 of the RNA polymerase CTD; releases RNA polymerase from the promoter?
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TFIIH
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What is the difference between eukaryotes and prokarotes when RNA is transcribed?
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Eukaryotes have different RNAs transcribed by different RNA polymerases while prokaryotes have a single type of RNA polymerase
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In both prokaryotes and eukaryotes what is gene expression regulated by?
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Gene Regulatory Proteins (transcription factors)
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What is another name for Gene Regulatory Proteins?
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transcription factors
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What is another name for transcription factors?
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Gene Regulatory Proteins
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What do Gene Regulatory Proteins bind to?
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Regulatory regions of DNA (cis element)
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What is another name for Regulatory regions of DNA?
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cis element
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What is another name for cis element of DNA?
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Regulatory regions of DNA
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Gene regulatory proteins can turn genes:
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on and off
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Positive regulators for gene regulatory proteins are called:
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activators
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Negative regulators for gene regulatory proteins are called:
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repressors
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What are activators?
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Positive regulators for gene regulatory proteins
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What are repressors?
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Negative regulators for gene regulatory proteins
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Is E. coli a prokaryote or a eukaryote?
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unicellular prokaryote
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what is the structure of e. coli's DNA?
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one chromosome of circular DNA
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how many proteins do E. coli encode?
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about 4300
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how are many of e. coli's transcriptionally regulated?
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by food availability
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what is an operon?
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a prokaryotic feature:
multiple genes can be transcribed into a single RNA molecule |
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operon is specific to prokaryotes or eukaryotes?
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prokaryotes
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what is it when multiple genes can be transcribed into a single RNA molecule?
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it is a prokaryotic feature called an operon
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how many genes are in a tryptophan operon?
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five genes
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what does the tryptophoan operon encode?
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it encodes enzymes for trptophan biosyntesis
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in the tryptophan operon what is transcription regulated by?
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it is regulated by a single promoter
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what does (Trp) stand for?
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Tryptophan as in the Tryptophan operon
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how many protein bound states does the Trp operon promoter have?
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2
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What are the Trp operon promoter 2 protein bound states?
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1. Bound by RNA polymerase
- Trp gene expression ON 2. Bound by a trptophan repressor protein - Trp gene expression OFF |
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When Trp operon is bound by RNA polymerase, is gene expression ON or OFF?
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ON
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When Trp operon is bound by a tryptophan repressor protein, is gene expression ON or OFF?
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OFF
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In Trp operon what does the tryptophan repressor bind to?
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it binds to a specific DNA sequence of the promoter called an operator
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In Trp operon what is the operator?
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It is where the tryptophan repressor binds a specific DNA sequence of the promoter
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What happens when tryptophan repressor binds?
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it blocks promoter access
-RNA polymerase cannot bind -negatively regulates Trp expression |
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How is trptophan repressor DNA-binding activity regulated?
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it must bind two molecules of trptophan to bind to DNA
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How is the trp repressor and operator regulated in terms of switching control of tryptophan biosynthese?
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by the availability of free tryptophan
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Gene expression for tryptophan is on for ..
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low tryptophan levels
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gene expression for tryptophan is off for...
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high tryptophan levels
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when tryptophan levels are low gene expression is on or off
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on
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when tryptophan levels are high, gene expression is on or off?
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off
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What kind of DNA binding motif does a tryptophan repressor contain?
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helix-turn-helix
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What is the most common DNA-binding motif?
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helix-turn-helix
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where does helix-turn-helix bind in DNA?
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in the major groove of DNA double helix
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What does tryptophan binding induce?
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conformational change so that it fits into major groove
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how many genes in the lac operon are required for the transport of lactose into the cell for its catabolism
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three
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what does the e. coli lac operon allow e. coli to do?
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it enables use of lactose in the absence of glucose
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What type of regulation does the lac operon employ?
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dual regulation, both positive and negative control
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what is the activator for the lac operon called?
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Catabolite Activator Protein (CAP)
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What is the Catabolite Activator Protein (CAP)?
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it is the activator for the e. coli lac operon
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In the lac operon what does the CAP do?
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promotes Lac expression
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in the lac operon when is CAP active?
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when there is low glucose and high lactose
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Whatis activated in the lac operon when there is low glucose and high lactose?
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The CAP activator which promotes Lac expression
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What is the repressor in the Lac operon?
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The Lac repressor protein
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In the lac operon what does the Lac repressor protein do?
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inhibits lac expression
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When is the Lac Repressor Protein activated?
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when there is low lactose
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what is activated in the lac operon when there is low lactose
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the Lac Repressor Protein
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Where does CAP bind in the lac operon?
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to the CAP binding site
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In the Lac operon what binds to the CAP binding site?
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CAP
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In the Lac operon what binds to the promoter?
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The RNA polymerase
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In the Lac operon, what does the RNA polymerase bind to?
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The RNA polymerase binding site or promoter
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In the Lac operon what binds to the operator?
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The Lac repressor
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In the Lac operon what does the Lac repressor bind to?
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the operator
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what does the first gene of the lac operon do?
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encodes B-galactosidase; breaks down lactose to glucose and glactose
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What encodes B-galactosidase and what does it do?
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It is the 1st gene of Lac operon and breaks down lactose to glucose and galactose.
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What breaks down lactose to glucose and galactose?
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B-galactosidase which is encoded by the 1st gene of Lac operon
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When is the Lac repressor bound to the operator?
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When lactose levels are low.
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When lactose levels are low, what binds to the operator
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the Lac repressor
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When the lac repressor is bound to teh operator, is Lac operon gene expression on or off
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off
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Increases in lactose increases levels of what?
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Allolactose
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What is allolactose?
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related to lactose and requires B-galactosidase
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What does allolactose do?
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it binds to the lac repressor
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what happens to the lac repressor when allolactose binds it?
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the lac repressor undergoes a comformation change
it decreases its DNA binding activity it realases from the operator |
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If the lac repressor is bound and the cap is not bound is gene expression on or off?
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off
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If both the lac operon and CAP are not bound is gene expression on or off?
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off
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what structure does CAP contain?
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a helix-turn-helix DNA binding domain
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what is requried for efficient RNA polymerase binding to Lac promoter?
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it is required that CAP is bound
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why need an activator/CAP?
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RNA polymerase binding is inefficient to Lac promoter
efficient RNA polymerase binding to Lac promoter requires CAP to be bound CAP contains a helix-turn-helix DNA binding domain |
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CAP DNA-binding activity is activated by what?
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low gluclose
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What do decreased glucolse levels do?
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it increases the levels of a signaling moleclue called cyclic AMP (cAMP)
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What happens to CAP protein when cAMP binds to it?
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it undergoes a conformational change
it increases DNA-binding activity it binds to CAP-binding site |
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What does CAP recruit
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it recruits RAN polymerase to the Lac promoter
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