Busy. Please wait.
or

show password
Forgot Password?

Don't have an account?  Sign up 
or

Username is available taken
show password

why


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.


Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
Don't know
Know
remaining cards
Save
0:01
To flip the current card, click it or press the Spacebar key.  To move the current card to one of the three colored boxes, click on the box.  You may also press the UP ARROW key to move the card to the "Know" box, the DOWN ARROW key to move the card to the "Don't know" box, or the RIGHT ARROW key to move the card to the Remaining box.  You may also click on the card displayed in any of the three boxes to bring that card back to the center.

Pass complete!

"Know" box contains:
Time elapsed:
Retries:
restart all cards
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

Bio Exam II

Gene Regulation

TermDefinition
lac operon model- the basics - e. coli: normal stomach bacteria, adjusts based on host - humans drink milk= e. coli digests lactose
Induction Turning on gene expression
inducer compound that stimulates gene expression
inducible enzyme -coded for by inducer gene - produced in response to inducer - contrast w/ constitutive enzymes
Operon - complex in DNA: group of genes with related functions - regulatory DNA sequences - promoter: RNA poly. binding site not transcribed - operator: "switch" sequence for gene expression - 3 genes: lac z, lac y, lac a
Negative regulation of lac operon - no lactose= operon off, no expressed - with lactose= operon expressed
Involves Repressor repressor gene: codes for repressor protein, regulates gene expression - always on constitutive expression - not always part of operon
Lac Repressor Activity - no lactose: repressor binds to operator - RNA poly. can bind promoter, can't transcribe genes
Lactose affects lac expression - lactose enters cell, converted to allolactose - binds 2nd site on repressor protein - inactive by changing structure= cannot bind operator - allolactose is a non-competitive inhibitor of repressor protein
Allolactose in the inducer - induces lac operon genes by inactivating the repressor protein - allows transcription to occur - results in low levels of lac expression
What is transcribed? - 1 long mRNA w/ all 3 genes - each gene w/ own start & stop codon
NO NUCLEUS transcription and translation happens simultaneously
Positive Control of Lac Operon - positive control: regulation by an activator that binds DNA to stimulate transcription (high expression when active) - lactose can be used for E - glucose present= use first - lac operon expression responds to lactose & glucose levels
Lac Promoter Inefficient - low affinity for RNA pol. - Solution: CAP- catabolic activator protein - increases affinity of promoter for RNA pol - CAP inactive alone - CAP active when bound to cAMPT: cyclic AMP (adenosine monophosphate)
Effects of CAP-cAMP - low glucose= cAMP increases - CAP-cAMP binds; CAP binding site next to RNA pol. binding site - increases RNA pol. binding - bonds double helix - = positive control ( increases expression)
Lac Operon Activity:4 Structures - high glucose/ no lactose= no CAP, repressed, no expression - no glucose/ high glucose= CAP, induced, high expression - no glucose/ no lactose= CAP, released, no expression - high glucose/ high lactose= no CAP, induced, low expression
Eukaryotic gene regulation - eukaryotic cells respond to envi. - multicellular: allows for specialization & organization - achieved through differential gene expression
Regulation of Transcription Initiation - more complex than prokaryotes - involves DNA sequences & transcription factors ( proteins that bind DNA) (promote or inhibit transcription initiation)
Post- transcriptional regulation - length of poly-a-tail affects level of expression
Alternative Splicing - different polypeptides from same gene
Post-Transcriptional Regulation - polypeptides often processed= final protein - must be folded correctly - often chemical modifications
Created by: tennadeleta.