Biochem Test 3
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Biochem Test 3
Biochem study cards
The process by which DNA is used as a template to make RNA, which can then be used to make proteins
What is the enzyme that catalyzes transcription?
What are the subunits for RNA polymerase?
Alpha, omega, beta, beta', and sigma
What do the subunits do?
They are receiving proteins
What is the actual composition of the enzyme?
What is the core enzyme?
What is the holoenzyme?
What is the purpose of the sigma subunit?
Provides specificity to the enzyme; the core enzyme will make RNA, but only randomly
What is the DNA strand called that is used to make RNA?
The template strand
What is the direction called that the enzyme travels?
What is the promoter?
The region where transcription starts. The first base to be transcribed is the TSS.
What is the pribnow box?
10 base pairs upstream of the TSS; part of the promoter.
What is the -35 element?
Found -35 BPs upstream of the TSS; together with the pribnow box and TSS is called the promoter.
What is the UP element?
Found between -40 and -60, it is included with the core promoter to make the extended promoter.
When does the sigma subunit detach?
After the enzyme binds to the core promoter and transcribes about 10 BPs.
What is the transcription bubble?
About 17 BPs long, it unwinds the the DNA and splits it apart to be read; produces - supercoiling downstream and + upstream.
What is the rate of transcription?
What are termination sites?
They tell the enzyme to stop; consist of 2 inverted repeats. Also called intrinsic terminination.
How does termination proceed?
Creates a hairpin coil which stops transcription by causing 2 weak H-bonds with U and T.
What is rho-dependent termination?
The rho protein chases down the enzyme and forms the hairpin, which slows transcription and causes it to dissociate.
What are the 4 ways transcription is regulated?
Alternative sigma factos, enhancers, operons, and transcription attenuation
How do alternative sigma factors regulate transcription?
Different sigma factors place the RNA polymerase differently on the DNA, causing another set of proteins to be produced.
What are enhancers?
DNA sequences that are upstream from the extended promoter that can be bound to proteins called transcription factors.
How do enhancers regulate transcription?
Transcription factors bind to the enhancers which cause a change in transcription.
What do promoters bind to?
What do enhancers bind to?
What is a response element?
Causes a change in metabolic condition, such as causing the production of a heat-shock protein.
What is a silencer?
Turns genes off.
What is an operon?
An organized region where all the genes for a metabolic pathway are turned on; ex: lac operon in E. coli
What three genes comprise the lac operon?
Beta-galactosidase, lactose permease, transacetylase
What is a repressor protein?
Binds to the operon so that the enzyme cannot bind.
What is an inducer?
Turns an operon on.
In E. coli, what acts as an inducer?
Allolactose causes a conformational change by binding to the repressor, which makes it fall off and allows RNA polymerase to attach and transcribe.