In positive control, the function of the activator molecule is
to
| increase the affinity of RNA polymerase to the promoter. |
| bind with repressor molecules to prevent them from blocking the operator. |
| increase the affinity of the inducer molecule to the promoter. |
| bind with inducer molecules to increase their affinity to the promoter. |
The activator increases the rate of transcription by increasing the affinity of RNA polymerase for promoters.
In positive control, the function of the activator molecule is to increase the affinity of RNA...
Which of the following statements is correct concerning operon gene control? Positive control requires an activator protein to stimulate transcription of the structural genes within an operon. In negative control, a repressor protein inhibits or turns off transcription of the structural genes within the operon. An inducible operon normally is not transcribed. It requires an inducer molecule to stimulate transcription either by inactivating a repressor protein in a negative inducible operon or by stimulating the activator protein in a positive...
1) The lac operon is… a) Positive repressible b) Both negative inducible and positive repressible c) Positive inducible d) Negative inducible 2) An activator regulatory protein… a) Is involved in negative regulatory control b) Is a cis acting regulatory element c) Recruits RNA polymerase to the promoter d) Prevents RNA polymerase from binding the promoter 3) For the lac operon, the presence of the substrate (lactose) activates the repressor. True or False? a) true b) false 4) cAMP… a) Activates...
9. Using the diagram of the lac operon (regulates transcription of genes for lactose metabolizing enzymes) below, draw the appropriate positions for RNA polymerase and the CAP activator molecule when CAMP is present. Then draw the appropriate position for the repressor molecule when lactose is present as an inducer. Finally, indicate whether or not transcription occurs. (8 pts) Promoter Operator Gene 1 Gene 2 Gene 3
An activator regulatory protein… a. Is a cis-acting regulatory element b. Recruits RNA polymerase to the promoter c. Prevents RNA polymerase from binding the promoter d. Is involved in negative regulatory control
The lac operon contains a DNA sequence known as the lac promoter (P or P+ for wild type; P– for mutant (RNA polymerase does not bind)) that serves as the RNA polymerase binding site. The lac operon also contains a DNA sequence known as the Lac operator (O or O+ for wild type; O– or Oc for mutant (lac repressor cannot bind)) which is the binding site for lac repressor. The lac repressor, a protein, is encoded by the lac...
Match each term associated with genes and control of gene expression with the appropriate description. A transcriptional unit" that consists of promoter multiple genes under the control of a single regulatory element. A transcriptional regulatory protein (prokaryotic or eukaryotic) which works by turning on or increasing gene transcription. activator The region of a gene to which RNA polymerase binds. Enhancer A transcriptional regulatory protein prokaryotic or eukaryotic) which works by turning off or decreasing gene transcription. repressor A molecule that...
The diagram below illustrates the LAC operon in its OFF state when the inducer molecule —lactose—is absent. Predict the ways in which the following conditions will affect the transcription of the lactose-utilization genes. OPERON Regulatory Promoter Operator_ gene Lactose-utilization genes DNA mRNA RNA polymerase cannot attach to promoter Active repressor Protein If a mutation in the regulatory gene results in a misfolding of the repressor protein so that it can no longer bind DNA, the lactose-utilization genes O Will be...
2.) Activator and helper. Figure 19.29B gives the fold change
for a genetic network with an activator and helper. However, it
contains several mistakes that we will fix here.
a.) Derive the formula for the fold change under the assumptions
of a weak promoter and �!"# $% ≫ �. Show that the fold change is
given by the formula below rather than that in the book. Hint: The
schematic in Figure 19.29B should be helpful in determining the
states and...
The gene machine program shows you what happens when lactose is present in E. coli, and how the lac operon is under negative control. However, the lac operon is also under positive control from a protein called CRP, eAMP Receptor Protein. The absence of the lac repressor is essential but not sufficient for effective transcription of the lac operon. RNA polymerase also depends on the presence of CRP. Like the lac repressor, which can bind to the DNA and lactose....
3. The CAP activator protein and the Lac repressor both control the Lac operon (see Figure 28-14). Fill out the table below with No expression, Low/Medium expression, or High expression to summarize when the Lac operon will be expressed in each of the three E. coli strains in the table. An example has been done for you. RNA polymerase- binding site (promoter) CAP binding site start site for RNA synthesis operator Lacz gene -80 -40 14080 nucleotide pairs Figure 08-14...