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Lecture #11
Gene Regulation
| Question | Answer |
|---|---|
| What is gene reguation? | abilities of cells to control their level of gene expression |
| What are structural genes? | They are regulated so proteins can only produce with certain amount and at certain time |
| Constitutive Genes | unregulated and have essentially the constant level of expression |
| What are the benefits of gene regulation | conserves energy in which proteins are only produced when needed; ensures gene are express in appropriate call type and correct stage in development |
| Gene Regulation in Prokaryote | a. when lactose are present, proteins are made b. when lactose are absent, no proteins are made |
| Where is the regulating point in gene regulation of prokaryote? | most common happens at the transcription and in which it control the rate of mRNA is translated |
| Where is the regulating points in gene regulation of Eukaryote? | most common in the transcription but also at RNA processing, translation, and post translation |
| Transcriptional regulation in bacteria | a. it involve regulatory transcriptional factors b. these factors are then bind to DNA in vicinity of a promoter and which it affect the transcription of one or more nearby genes |
| What does repressor have affect on transcription? | it inhibits transcription and its the negative control |
| What does the activator do? | it increase the rate of transcription and positive control |
| What are the allosteric effector molecules? | these molecules binds to regulatory transcription factor and cause conformation change |
| What are the 2 domains in regulatory transcriptional factor? | 1. site where proteins binds to DNA 2. site for allosteric effector molecule |
| Where do allosteric effector binds to? | regulatory proteins |
| What is the operon? | a cluster of genes under transcriptional control of one promoter and has regulatory region called operator |
| What is polycistronic mRNA? | encodes for more than one protein |
| What is lac operon? | in E.Coli, it contains genes for lactose metabolism |
| lac P | promoter |
| 3 structural genes in lac operon | 1.lacZ - B-galactosidase 2.lacY - lactose permease 3.lacA - galactosidase transacetylase |
| Near the lac promoter, what are the two regulatory sites? | 1.lacO - Operator-provides binding site for represor protein 2.CAP site - activator protein binding site |
| What is lacI gene? | code for lac repressor and this is consider as a regulatory gene since its sole function is to regulate other gene expression |
| What happen when there isnt any lactose present? | lac repressor protein bind to nucleotides of lac operator site in which prevent RNA polymerase from transcribe the proteins RNA polymerase can bind but cannot move forward |
| When there is lactose present? | allolactose is an allosteric effector molecule and this will binds to lac repressor in which prevents from it binding to DNA; and this process is called Induction and therefore lac operon is inducible |
| What is the induction? | Its the process in which allosteric molecules are there to bind into repressor and prevent it from attaching to DNA |
| What is the IPTG? | Its an artificial inducer of the lac operon; it can enter the cell without lacY and doesnt need to be converted into lacZ like lactose. |
| What is the imprecise excision? | Its an integrated F factor that forms an extrachromosomal plasmid that include the host |
| What is the merodiploid? | its the F prime with lac operon that can be transferred to recipient by conjugation |
| What are the two classes of mutants? | Constitutive and non-inducible |
| What is CAP? | an activator |
| What is cAMP? | a small effector that binds to CAP |
| What does level of Glucose have to do with cAMP? | a. High level of Glucose - no cAMP b. Low level of Glucose - cAMP |
| CAP + cAMP= ? | When there is low level of glucose, these two complex bind to DNA and transcription occurs |
| What happen when there is high level of glucose an lactose? | lac operon is shut off, CAP does not activate transcription because bacteria would use glucose first and produce low level of cAMP |
| What happen when there low level of glucose and high at lactose? | The lac operon is turned on, allolactose level is high and it attaches to lac repressor and CAP is now bind onto CAP site with cAMP |
| What happen when there low level of lactose and glucose? | lac operon is shut off and CAP is inactive with low level of cAMP and also lac repressor binds to lac operator. |
| Trytophan | a. levels low= trp repressor cannot bind to operator sites and operon genes get transcribe b. trypophan level high= turn off trp operon |
Created by:
mung44
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