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Control gene express
Bio 2 Lecture 15
| Question | Answer |
|---|---|
| What's the purpose of gene regulation? | Turn on genes that need to be expressed and turn off genes that are not needed |
| When do cells need to regulate gene expression? | For rapid adjustement to environmental changes: like for food availability and amino acids required for growth |
| Prokaryotic Expression Uses Feedback Mechanisms at Several Levels… What are they? | Regulate metabolism and regulate gene expression |
| What are the 3 levels of control in bacteria? | Change rate of transcription, chnage life span of mRNA and change rate of translation |
| What are operons? | A cluster of genes under the control of a single promoter (make enzymes for a single pathway.) |
| What will the regulator protein do? | The regulator protein will block or unblock the promoter site thus controlling transcription. |
| What does an operon contain? | A promoter site (RNA polymerase binding site, synthesizes mRNA), operator within promoter site (on/off switch), structural genes (code proteins aka enzymes) and a regulator gene (codes fr a regulator protein, turns the operon on/off located upstream) |
| What will the regulatory protein bind to? | The regulatory protein from the regulatory gene will bind to the OPERATOR SITE when the regulatory protein is in its active form, potentially blocking gene expression |
| What do structural genes do? | STRUCTURAL GENES each coding for a protein for enzymes used in the same pathway. |
| Identify all the parts of an operon | promoter region, operator site, structural genes and regulatory site |
| Again, what does the regulatory gene do? | Upstream of the operon, it codes for the regulator protein. |
| If the regulatory gene makes an active regulator protein... | the regulator protein can bind to the operator thus blocking RNA polymerase |
| Why is negative gene regulation considered negative? | Bc the active form of the regulatory protein turns off transcription |
| What is a inducer and repressor regulatory protein? | Inducer means it's active when its made and repressor means its inactive when its made (but can become active due to the environment). |
| Lac operon makes an ... regulatory protein | inducer (active when madde) |
| Trp operons make a ... regulatory protein | repressor (inactive when made) |
| What does the active and inactive form does to transcription? | Active blocks transcription and inactive doesn't |
| A regulator made in its active form binds to what? example | To the operator, turning off the operon. Lac operon doesn't make enxymes to breakdown lactose |
| A regulator made in its inactive form binds to what? example | Nothing, unable to bind to operator so the operon is transcribed. Trp operon: the enzymes to make tryptophan are made |
| Is the inducible operon normally on or off? Why? | Normally off since the metanolite is not being used bu the bacteria (only be use when its preferred metabolite runs out). |
| Is the repressible operon normally on or off? Why? | Normally on bc the cell needs the produt of the pathway to live |
| What are the 3 structural genes for lactose transportation and metabolism in E. coli bacteria? | lac Z, lac Y and lac A |
| What's the effect of lac I structural gene? | makes the repressor protein (RP) upstream of the operon. This is the regulator protein that will bind to the operator if it is in its active form. |
| Using ur logic, is lac operon normally on or off? Why? | Lac operon is normally off because E coli prefer other sugars which are frequently available in their environment. The lac operon will be activated if lactose is the only available sugar. |
| Using ur logic, is trp operon normally on or off? Why? | On bc E coli need the tryptophan AA for protein synthesis. If tryptophan is available in the envi., E coli will regulate the operon by using the envi. trp as a switch to activate the repressor protein & turn off synthesis of genes to make trp synthetase |
| What are the structural genes of trp operon? | trp E, trp D, trp C, trp B, trp A and trp R |
| What does trp R produce? | Produces a repressor protein upstream of the operon |
| When do cells need to regulate gene expression? | Eukaryotic cells turn on and off gene to ensure homeostasis |
| When can regulation happen for both eukaryotic and prokaryotic? | Regulation can occur at any stage of information flow (DNA to RNA to Protein) for eukaryotic but only at 3 levels for prokaryotic. |
Created by:
Malayka
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