Chapters 16-22 Flashcards
(228 cards)
Where is the regulatory sequence, and what is located here?
generally in 5’ region. promoter is located here
What is the function of transcription factors?
affect RNA polymerase’s ability to bind can bind within regulatory region can help or hurt RNA polymerase
What are the two main motifs that recognize where to attach to DNA?
DNA binding motif leucine zipper motif
What is the DNA binding motif?
repeated structure in the protein EX. helix-turn-helix
What is the leucine zipper motif?
found repeatedly on proteins contains a zipper like protein
What is an operon?
grouping of proteins found only in prokaryotes genes necessary to make the enzymes necessary for a particular product
What is trp operon?
gene necessary to make the enzymes to make the amino acid tryptophan
What is the structure of trp operon?
coding region regulatory region
What is the regulatory region in a trp operon?
Contains a promoter
What sits on the promoter in trp operon?
RNA polymerase
What is an operator?
Binding site for a transcription factor
How does this operon work? When is it on, when is it off?
If tryptophan is absent the cell needs it - promoter is unoccupied and operon is on If tryptophan is present- promoter is occupied and the operon is off
What does the lac operon do?
produces the necessary enzymes to digest loctose
Is the lac operon a weak promoter or a strong promoter?
Weak promoter
What does CAP stand for?
Catabolite activator protein
What happens when glucose is low in a bacteria?
Bacteria must use a different sugar like lactose
What are the three things that happen in bacteria when glucose is low?
Then [cAMP] is increase, cAMP binds to CAP CAP binds to DNA allowing RNA polymerase to bind to lac operon
What is cAMP?
little molecule that is like ATP
What are the three genes within the coding region of a lac operon?
Z, Y, A
What are the three sections of the regulatory region in the lac operon?
Promoter operator CAP binding site
What happens if [glucose] is low and [lactose] is high?
RNA polymerase attaches to promoter and transcription occurs
What happens if [glucose] is low and [lactose] is low?
repressor attaches to operator
What must happen in order to for the lac operon to be on?
[glucose] low, and [lactose] higher
What are specific transcription factors?
they stick out of general transcription factors and attach to other parts of DNA called enhancers




