Test 2
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what is the centra dogma again? and where does it happen
DNA-> RNA-> Proteins, the cytoplasm of prokaryotes
Operons
A collection of genes arranged in tandem that are transcribed into a single RNA under the control of a single promoter
promoter
region of DNA needed for transcription initiation anf the binding of RNA polymerase
Regulator Protein
can help sense internal changes and alter the gene expression to match those changes types are activators and repressors
operator
region of DNA where repressor proteins can bind
activator
region where activator proteins can bind
What do regulator proteins look like?
symmetry that involves inverted repeat. (look up image)
DNA sequence control vs protein seqence control
DNA sequence control is the most drastic and least reversible, while portion is the most rapid and most reversible
What are the two forms regulatory proteins come in?
Repressors or activators, bind to regulatory sequences and influence transcription
Most____must first bind to a small ligand
activators
French scientists Jacques Monod and François Jacob are known for what?
They proposed the idea that genes could be regulated and noticed that genes involving lactose were inducible and genes involving glucose were constitutive
What does LacZYA do in the absecne of lactose?
The repressor LacI binds to Lac O which overlaps with the promotor lac P creates these loops and prevents from DNA transcription
What does LacZYA do in the presence of lactose
b-galactosidase (LacZ). Breaks and rearranges lactose to make allolactose. Alloacotse then binds to the LacI allowing induction of the operon
How does cyclic AMP accumulate in the E.coli cell
When the cell is “starved” for carbon
The maximum expression of lac operon required what
the expression of cAMP and the cAMP receptor protein, that complex (cAMP-CRP) bonds to the promoter and increases the rate of initiation
Catabolite repression
the catabolism of one nutrient is repressed by the presence of a more favorable nutrient (often glucose)
diauxic growth
biphasic curve of a culture growing on two carbon sources is often called
Inducer exclusion
Glucose transport inhibits the lacY permease activity, causing lactose not to be able to enter the cell, lacZYA cannot be induced
Genes encoding biosynthetic enzymes are regulated by repressors called?
aporepressors
What do aporepressors bind to?
corerepressors
What happens to the Trp operon when levels of Trp exceed what is needed in the cell?
The excess trp(the corerepressor) will bind to the inactive aporerepressor. This creates a holorepressor which binds to the operator.
Draw out the scenerios of the repressor and the repressor corepressor complex
I went to the ipad and know how to do this.
sensor kinase
in the cell membrane -binds to the environmental signal and activates via phosphorylation That phosphate is the one that binds to active or inhibit the signal it later gets removed by phosphatase
response regulator
in the cyctoplasm, takes the phosphate from the sensor and binds to chromosome and then alterns that transcription rate step 2 of the two-componets signal transduciton