Biology 1202B Study Guide - Midterm Guide: Plasmid, Oncogene, Rna Interference

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erinfox426

22 Apr 2017

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Essential outcomes regulation of gene expression: describe the phenomenon and function of differential gene expression in general terms. Differences in gene expression are a result of regulation of gene expression that occur in the same set of genes. The presence or absence of products that are produced from the expression of genes explain the functional and structural differences in various types of cells. Genes that are more likely to be actively transcribed are often considered to be turned on : compare and contrast the regulation of gene expression in e. coli for the lac operon versus the trp operon. Controlled by a lac repressor which encodes for laci. When allolactose is present, it binds to the repressor and inactivates it which allows the operon to be transcribed. When tryptophan is present, it binds to the repressor and activates it, which prevents the operon from being transcribed. Both are examples of negative gene regulation.

Related Questions

1. When glucose and lactose are both present? select all thatapply.

the operon is NOT expressed

only the activator binds the DNA

the activator and the repressor bind the DNA

the activator and repressor do not bind the DNA

The operon is expressed

Only the repressor binds the DNA

2. What is the function of the following, using the optionsbelow?

cAMP

lactose

operator

Options: DNA sequence where regulatory proteins bind, binds andinactivates the repressor, binds and inactivates the activator,binds and activates the activator, binds and activates therepressor

harlequinbat245

1.) What type of control best describes the lac operon when it is regulated by allolactose? Explain the features of this type of regulation using the lac operon as an example.

2.) What is positive gene regulation?

a) when an activator protein binds to the operator of a gene to turn expression off

b) when a repressor protein binds to the operator of a gene to turn expression off

c) when an activator protein binds to the operator of a gene to turn expression on

d) when a repressor protein binds to the operator of a gene to turn expression on

e) when a protein binds to DNA to change gene expression

3.) In the lactose operon of E. coli, what is the function of each of the following genes or sites: a) regulator, b) operator, c) promoter, d) structural gene Z and e) structural gene Y?

a) regulator gene

b) operator

c) promoter

d) structural gene Z

e) structural gene Y

4.) In a negative, repressible regulatory mechanism, transcription of the structural gene(s) occurs in

a) the presence of the co-repressor, but not in its absence.

b) the absence of the co-repressor, but not in its presence.

c) the presence of the inducer, but not in its absence.

d) the absence of the inducer but not in its presence.

e) the absence or presence of the co-repressor.

What are answers and can you explain them to me?

Regulation of Gene Expression Question. Help with regulatory proteins (operators) and protein binding sites!!

1. In studying the bacterial the srp operon, you have isolated two different mutants (con1 and con2) that cause constitutive expression of the srp operon (constitutive expression of srp1 and srp2). One of the mutants has a mutation in a DNA binding site (e.g. operator), and the other has a loss-of-function mutation in the gene that encodes a protein that binds to the DNA binding site (e.g. repressor protein).

You perform an analysis using partial diploids to determine which of the two mutants has a defect in the binding site and which of the two mutants has a mutation in the gene encoding the binding protein.

a. Assuming you can assay levels of the two Srp proteins, what results do you predict for the two strains (i and ii below) if con2 encodes the regulatory protein and con1 is the regulatory binding site? In predicting results, indicate whether expression of the Srp1 and Srp 2 proteins will be constitutive or inducible (you will circle an answer in the bolded region below). 2 pts

i. (a) con1^-con2⁺srp1^-srp2⁺/ (b) con1⁺con2⁺srp1⁺srp2^-

ii. (a) con1⁺con2^-srp1^-srp2⁺/ (b) con1⁺con2⁺srp1⁺srp2^-

b. What results do you predict for the two strains (i and ii) if con1 encodes the regulatory protein and con2 is the regulatory binding site? 2 pts

Answer for a(i) (circle either constitutive or inducible for each gene):

srp1 constitutive / inducible

srp2 constitutive / inducible

Answer for a(ii) (circle either constitutive or inducible for each gene):

srp1 constitutive / inducible

srp2 constitutive / inducible

Answer for b(i) (circle either constitutive or inducible for each gene):

srp1 constitutive / inducible

srp2 constitutive / inducible

Answer for b(ii) (circle either constitutive or inducible for each gene):

srp1 constitutive / inducible

srp2 constitutive / inducible

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Biology 1202B Study Guide - Midterm Guide: Plasmid, Oncogene, Rna Interference

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