Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
33 Cards in this Set
- Front
- Back
|
What are the basic steps leading from the information coded in DNA to a functional Protein in Bacteria?
|
Transcription, Translation, Posttranslation.
|
|
|
What are the two approaches to regulation?
|
Regulation of gene expression and to alter the activity of enzymes and proteins
|
|
|
How do cells regulate transcription?
|
Replacement of degraded enzymes via constitutive genes, inducible genes, repressible genes.
|
|
|
When are enzymes that function in the biosynthetic pathway not present? Why?
|
When the end product in the biosynthetic pathway is available. Because there isn’t a need to make an enzyme to make the product if the damn thing is already there. Why would you make a cake making machine, if you had a surplus of unlimited cakes in your house?! Don’t waste time, eat those cakes in your house before they spoil :D
|
|
|
What do regulatory proteins control?
|
Transcription initiation
|
|
|
Why does induction and repression occur in cells?
|
Regulatory proteins containing DNA binding domains which either inhibit transcription or promote transcription
|
|
|
How does negative transcriptional control work?
|
Bind a repressor to an operator to stop the initiation of transcription. You are REDUCING mRNA expression
|
|
|
What is an inducer?
|
Substrate
|
|
|
What is a corepressor?
|
Enzymatic products
|
|
|
How does positive transcriptional control work?
|
You bind an activator to an activator binding site to promote transcription initiation. You are INCREACING mRNA synthesis
|
|
|
Why is synthesis of enzymes for metabolic processes turned on and off?
|
Because you don’t need to have an enzyme for a substrate that isn’t there. Cells are efficient as all hell. (which I guess must be pretty efficient?)
|
|
|
Does Lac operon use + or – control?
|
Negative Control via the LacI repressor (tetramers)
|
|
|
What does positive control of the Lac operon?
|
CAP
|
|
|
When does trp operon function?
|
Only in the absence of tryptophan
|
|
|
How is transcription elongation regulated?
|
Controlling transcription termination (attenuation) and riboswitches
|
|
|
How does attenuation work?
|
It is the termination of transcription within a leader region, so transcription is terminated before the gene is transcribed. It works by stem loop structures in the mRNA. Two hairpin loops form in the mRNA due to the RNA poly pausing twice. The 2nd pause destabilizes the mRNA is the terminator
|
|
|
How do riboswitches work?
|
There are two folds in the mRNA. A fold that will turn expression on, and a fold that will turn gene expression off.
|
|
|
If an effector molecule binds to the mRNA, will the riboswitch turn gene expression on or off?
|
Off
|
|
|
How do riboswitches affect translation of mRNA?
|
It can block the shine dalgarno sequence. The effector binds in the 5’ region of the mRNA and messes with the folding pattern.
|
|
|
Are riboswitches cis acting or trans acting regulators? Why?
|
Cis acting. They are a part of the same RNA transcript that they regulate. They are a molecule which binds to the mRNA they’re messing with.
|
|
|
Do sRNA regulate translation or transcription?
|
Translation
|
|
|
How do sRNA molecules regulate translation?
|
They’ll base pair to the mRNA and inhibit or inhance translation.
|
|
|
Are sRNA trans or cis acting regulators?
|
Trans. The mRNA they act on isn’t a part of the same transcript
|
|
|
How can genes/pathways be simultaneously affected by regulators and the regulatory systems?
|
Global regulators
|
|
|
Why are global regulators important for bacteria?
|
They must reposnd rapidly to a wide variety of changing conditions
|
|
|
What are regulons?
|
A set of genes or operons that are controlled by a common regulatory protein
|
|
|
What are the mechanisms used for global regulations?
|
Two component signal transduction systems, phosphorelay systems, regulatory proteins, alternative sigma factors.
|
|
|
What do TSCTS do?
|
Link external events to regulation of gene expression. It’s bacteria’s common gene expression regulation technique
|
|
|
What regulatory system is used by all 3 domains of life?
|
Two component regulatory systems.
|
|
|
What are the two proteins found in the two component regulatory syste,?
|
Sensor kinase and response-regulator protein
|
|
|
What is the OMPR/ENVZ two component signal transduction work?
|
It regulates expression of outer membrane proteins depending on osmolarity
|
|
|
What does OMPC do?
|
Makes a smaller pore in the membrane. It’s dominant in high osmolarity, and cells which need lower diffusion into a cell (like in the intestinal tract)
|
|
|
What does ompF do?
|
Makes a larger pore in the membrane. Dominant in dilute environments and allows for more diffusion of solutes.
|
