Term
| What three things do control circuits provide? |
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Definition
Conserve energy + resources.
Feedback inhibition + homeostasis
Environmental Sensing |
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Term
| Name the four types of circuit control. |
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Definition
1-Negatively-controlled inducible
2-Negatively-controlled repressible
3-Positively-controlled inducible
4-Positively-controlled repressible |
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Term
| What are anti-sigma factor control systems? |
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Definition
| Anti-sigma factors bind to sigma subunit, and inhibit transcriptional activation. |
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Term
| Where would anti-sigma factors be used/found? |
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Definition
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Term
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Definition
| A genetic unit of co-ordinated expression, which is under the control of one operator gene. |
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Term
| What three genes are found on the lac operon? |
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Definition
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Term
| What three proteins do lacZ, lacY and lacA encode? |
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Definition
lacZ = beta-galactosidase
lacY = Permease
lacA = transacetylase |
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Term
| What is the function of beta-galactosidase? |
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Definition
| Converts lactose --> galactose + glucose |
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Term
| What are the functions of lactose permease and transacetlyase? |
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Definition
| Help to transport the lactose into the cell, complete function of transacetylase is unknown. |
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Term
| Which two scientists were responsible for discovering the induction of the lac operon? |
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Definition
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Term
| What did Jacob + Monod discover? |
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Definition
| beta-galactosidase was induced 1000 fold in presence of inducers. |
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Term
| DRAW THE LAC OPERON,IN HIGH GLUCOSE + LACTOSE CONDITIONS, AND LOW GLUCOSE AND HIGH LACTOSE CONDITIONS. |
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Definition
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Term
| If levels of glucose are high, how will the conc. of cAMP respond? |
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Definition
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|
Term
| What provides another level of control on the lac operon? |
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Definition
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Term
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Definition
| Catabolite Activator Protein - an inducer for the lac operon, which triggers RNA binding. |
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Term
| What system does catabolite repression adhere to? |
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Definition
| +ively-controlled inducible system. |
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Term
| What happens if there is no cAMP-CAP complex present in high glucose conditions? |
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Definition
| There will be no transcription. |
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Term
| On what the 3 levels is trp biosynthesis controlled? |
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Definition
1- A repressor binds to the operator seq.
2-Anthranilate synthase is subject to feedback inhibition.
3-Transcription attenuation. |
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Term
| Who was responsible for carrying out experiments on the trp operon. |
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Definition
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Term
| What is found between the operator and trpE gene? |
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Definition
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Term
| What does the leader sequence consist of? |
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Definition
| 5 regions, which contain two coding regions for trp. |
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Term
| What does trpE and trpD encode? |
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Definition
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Term
| What do trpC, trpB, and trpA encode? |
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Definition
trpC = Anthranilate isomerase
trpB = Tryptophan synthase-beta
trpA = Tryptophan synthase-alpha |
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Term
| What do the proteins encoded by the trp operon contribute toward? |
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Definition
| The synthesis of Tryptophan |
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Term
| How does the leader sequence regulate transcription of the trp operon? |
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Definition
| Through Attenuation. A process where region of the leader sequence can form a stem-loop structure, which either inhibit or allows for transcription to continue. |
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Term
| If regions 2 + 3 of the leader sequence interact, what structure is formed? |
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Definition
| An anti-terminator stem loop, translation can continue. |
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Term
| If regions 3 + 4 of the leader sequence interact, what structure is formed? |
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Definition
| A terminator stem-loop, translation is inhibited. |
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Term
| Why can the regions of the leader sequence interact? |
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Definition
| As the sequences for the regions is palindromic, so they nucleotides compliment each other. |
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Term
| In what conditions will the anti-terminator stem loop structure form? |
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Definition
|
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Term
| In what conditions will the terminator stem-loop form? |
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Definition
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Term
| How many genes in Bacillus subtilis encode for proteins which synthesise tryptophan? |
|
Definition
| 7 (v. similar to E. coli) |
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Term
| Where and why is trpG located? |
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Definition
| In two operons, as it functions in both tryptophan and folate synthesis. |
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Term
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Definition
| trp RNA-Binding Attenuation Protein. |
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Term
| How does TRAP effect transcription? |
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Definition
| Funstions like a stalled ribosome, but promotes a termination stem-loop not an anti-termination stem-loop. |
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Term
| Describe the structure of TRAP. |
|
Definition
11 identical subunits, arranged in a doughnut shape.
RNA-binding regions found on the outer surface, and a trp-binding region formed b each pair of adjacent subunits. |
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Term
| What system is transcription attenuation is B. subtilis? |
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Definition
| A -ively-controlled repressible system. |
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