Assign. 25 Practice Problem 81 - Copy2 Imagine you are carrying out research on the lac...
Imagine you are carrying out research on the lac
operon. You isolate six mutations in the lac operon by
measuring the amount of beta-galactosidase made in mutant cell line
under three different conditions: no lactose/no glucose; lactose
only; and lactose/glucose. Your results are shown in the table.
Strain
No Lactose, No Glucose
Lactose
Lactose, Glucose
Wild-type
None
High
Low
Mutant 1
None
None
None
Mutant 2
None
None
None
Mutant 3
None
Low
Low
Mutant 4
None
Low
Low
Mutant...
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...
In the lac operon, what are the likely effects on operon transcription of the mutations listed below? PLEASE EXPLAIN your answers. I think I answered the first part of the question but need help explaining why. Mutation of the consensus sequence in the lac promoter. i. Transcription is blocked. Mutation of the repressor binding sites in the operator sequences. i. Transcription is constitutive. Mutation of the lacI gene affecting the allosteric site of the protein. i. Transcription is blocked. Mutation...
In the lac operon, 1 codes for the repressor protein, P is the promoter which is necessary for binding RNA polymerase, O is the operator, and Z codes for the B-galactosidase. Assuming (+) denotes the wild type for a particular locus, (-) denotes a lack of a particular gene product or function, O^c is a constitutive operator, and I^s is a super repressor. Use a "+++" sign to indicate that significant quantities of functional B-galactosidase are present, a '+' sign...
4. Nutritional status, mutation, and expression of the lac operon. For each of the following conditions, indicate how much (a lot, a little, or none) of the lacZ gene (z-gene) product, beta- galactosidase, is being synthesized. NUTRITIONAL STATUS OF THE BACTERIA +lactose/-glucose +lactose/+glucose -lactose/+glucose genetic status normal (no mutation) mutation a mutation b mutationc important: these are nor the same mutations as the ones in your class handout mutation a: a mutation in the start codon for the lacA (A-gene)...
B2. Consider E. coli cells, each having one of the following mutations: a) a mutant lac operator (Oc locus) that cannot bind repressor. b) a mutant lac repressor (I- gene product) that cannot bind to the lac operator. c) a mutant lac repressor (the Is gene product) that cannot bind to lactose. d) a mutant lac promoter that cannot bind CAP + cAMP. What effect would each mutation have on the function of lac operon (assuming no glucose is present)...
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...
You are asked to develop a demonstration to show how the
lac operon works. You decide to use X-gal and IPTG to
determine if the enzyme ?-galactosidase is active. X-gal is a
lactose analog that turns blue when metabolized by ?-galactosidase,
but it does not induce the lac operon. IPTG is an inducer
of the lac operon, but is not metabolized by ?-galactosidase.
a. (2pts) Which of the following would you expect to bind to
?-galactosidase. Circle all that apply....
for
1-5 define those
The Lac operon is an inducible set of genes found in bacteria cells that helps the bacteria to metabolize the disaccharide lactose. When it is turned on it produces proteins that pump lactose into the bacteria cell and break it down into glucose and galactose, which can then be used by the bacteria as a source of energy The two figures below show the Lac Operon along with the lacl gene (which regulates the Lac operon...
You have systematically mutagenized the lac operon in E. coli to produce a mutation that disrupts the function of each of the following elements: a. the promoter for LacI (P(I)) b. the LacI gene c. CRP binding site d. the promoter for the lac operon (P(lac)) e. the operator sequence f. a mutation in lacZ that disrupts the coding region but does not disrupt transcription g. a mutation in lacZ that blocks transcription For each of the above mutations, what...