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Chapter 14 Questions
Genetics Chp 14 Questions
| Question | Answer |
|---|---|
| examples of genetic regulatory proteins and small effector molecules | activators and repressor's are regulatory proteins. Inducers, covert pressers, and inhibitors are small effector molecules |
| a repressor is a______ that_____ transcribes | regulatory protein, inhibits |
| what would cause transcription to be activated | a repressor + inducer |
| which genes are under the control of the lac promoter | the lacZ, lacY, and lacA genes are under the control of the lac promoter |
| under what conditions is the lac repressor bound to the lac operator | the lac repressor is bound to the lac operon when it is not exposed to lactose. When allolactose is not bound to the repressor |
| why is it beneficial for the bacterium to regulate the lac operon with both a repressor protein and an activator protein | the repressor protein allows the cell to avoid turning on the operon in the absence of lactose. The activator protein allows the cell to choose between glucose and lactose |
| which data provide the strongest evidence that O1 is not the only operator site | the data in which O2 and O3 are deleted indicate that O1, by itself, is not very strong in repressing the lack operon |
| what is an operon | a group of genes under the control of a single promoter |
| the binding of _____ to the lac repressor causes the lac repressor to _____ to the operator site, thereby _____ transcription | allolactose, not bind, increasing |
| on its chromosome, and E. coli cell is lacI- lacZ+ lacY+ lacA+. it has an F' that is lacI+ lacZ+ lacY+ lacA+. What is the expected level of expression of the lac operon genes (lacZ+ lacY+ lacA+) in the absence of lactose | neither lac operon would be expressed |
| how does exposing E. coli cell to glucose affect the regulation of the lac operon via CAP | cAMP does not bind to CAP and transcription is decreased |
| how does tryptophan affect the function of the trp repressor | tryptophan acts as a co-repressor that causes the trp repressor to bind to the trp operon and repress transcription |
| what type of bonding interaction causes the stem loops to form | hydrogen bonding between complementary sequences causes the stem loops to form |
| explain how the presence of tryptophan favors the formation of the 3-4 stem loop | the presence of tryptophan causes the trpL gene to be translated to it stop codon. This blocks the regions one and two, which allows a 3– 4 stem loop to form. The 3– 4stem loop causes transcriptional termination |
| when tryptophan binds to the trp repressor, this causes the trp repressor to _____ to the trp operator and _____ transcription | bind, inhibit |
| during attenuation, when tryptophan levels are high the _____ stem loop forms and transcription _____ the trpL gene. | 3-4 , ends just past |
| operons involved with the biosynthesis of molecules, such as amino acids, are most likely to be regulated in which manner | the product of the biosynthetic pathway represses transcription |
| which micF anti-sense RNA affect the translation of the ompF mRNA | the micF antisense Rna binds to the ompF mRNA and inhibits its translation |
| why is feedback inhibition and advantage to bacterium | feedback inhibition prevents a bacterium from over producing the product of a metabolic pathway |
| translation can be regulated by | translational repressor's and anti-sense RNA |
| an example of a post-translational Koval and modification that may regulate protein function is | phosphorylation, acetylation and methylation |
| which RNA confirmation favors transcription- the form with the anti-terminator stem-loop or the form with the terminator stem loop | the RNA confirmation with the anti-terminator stem loop favors transcription |
| which RNA confirmation favors translation- the form with the Shine-Dalgarno anti-sequester or the form in which the Shine-Dalgarno sequences within a stem loop | the RNA confirmation with the Shine-dalgarno anti-sequester favors translation |
| for a rival switch that controls transcription, the binding of a small molecule such as TPP controls whether the RNA | has an anti-terminator or terminator stem loop |
| gene regulation | the phenomenon in which the level of gene expression can vary under different conditions |
| constitutive of genes | a gene that is not regulated and has essentially consistent levels of expression over time |
| repressor | a regulatory protein that binds to DNA and inhibits transcription |
| activator | a transcriptional regulatory protein that increases the rate of transcription |
| negative control | transcriptional regulation by repressor proteins |
| positive control | genetic regulation by activator proteins |
| inducer | a small effector molecule that binds to a genetic regulatory protein and thereby increases the rate of transcription |
| inducible genes | a gene that is regulated by an inducer, which is a small effector molecule that causes transcription to increase |
| corepressor | a small effector molecule that binds to a repressor protein thereby causing the repressor protein to bind to DNA and inhibit transcription |
| inhibitor | a small effector molecule that binds to an activator protein, causing the protein to be released from DNA, thereby inhibiting transcription |
| repressible genes | a gene that is regulated by a corepressor or inhibitor, which are small effector molecules that cause transcription to decrease |
| enzyme adaption | the phenomenon in which a particular enzyme appears within a living cell after the cell has been exposed to the substrate for the enzyme |
| operon | an arrangement in DNA in which two or more genes are found within a regulatory unit that is under the transcriptional control of a single promoter |
| polycistronic mRNA | an mRNA transcribed from an operon that encodes two or more proteins |
| promoter | a sequence within a gene that initiates transcription |
| Terminator | a sequence within a gene that signals the end of transcription |
| CAP site | the sequence of DNA that is recognized by CAP |
| operator site | a sequence of nucleotides in bacterial DNA that provides a binding site for genetic regulatory protein |
| lac repressor | a protein that binds to the operator site of the lac operon and inhibits transcription |
| induced | a gene that has been transcriptionally activated by an inducer |
| allosteric regulation | a phenomenon in which an effector molecule binds to a noncatalytic site on a protein and causes a conformational change that regulates its function |
| allosteric site | the site on a protein where a small effector molecule binds to regulate the function of a protein |
| merozygote | a partial diploid strain of bacteria containing F' factor genes |
| trans-effect | an effect on a gene expression that occurs even though to DNA segments are not physically adjacent to each other. Trans-effects are mediated through diffusible genetic regulatory proteins |
| trans-acting factor | a regulatory protein that binds to a regulatory element in the DNA and exerts a trans effect |
| catabolite repression | the phenomenon in which a catabolite represses the expression of certain genes |
| diauxic growth | the sequential use of two sugars by a bacterium |
| cAMP | in bacteria, a small effector molecule that binds to CAP. In eukaryotes, cAMP functions as a second messenger in a variety of intracellular signaling pathways |
| attenuation | a mechanism of genetic regulation, seen in the trp operon, in which a short RNA is made but it's synthesis is terminated before RNA polymerase can transcribe the rest of the operon |
| trp repressor | a protein that binds to the operator side of the trp operon and inhibits transcription |
| attenuator sequence | a sequence found in certain operons in bacteria that stops transcription soon after it has begun |
| post-translational | describes events that occur after translation is completed |
| translational regulatory protein | a protein that regulates translation |
| translational repressors | a protein that binds to mRNA and inhibits its inability to be translated |
| anti-sense RNA | and RNA strand that is complementary to a strand of mRNA |
| feedback inhibition | the phenomenon in which the final product of a metabolic pathway inhibits an enzyme that acts early in the pathway |
| allosteric enzyme | an enzyme that contains to binding sites: a catalytic site and a regulatory site |
| post-translational covalent modification | the covalent attachment of a molecule to a protein after it has been synthesize a via ribosomes |
| riboswitch | a mechanism for regulating transcription, translation, RNA stability, and splicing in which an RNA molecule can switch between two secondary confirmations based on whether or not a small molecule, such as TPP, binds to the RNA |
| anti-terminator | the function of certain proteins, such as N protein in bacteria, that prevents transcriptional termination |
Created by:
banken