LacZ codes for
beta-galactosidase enzyme which converts CPRG (yellow-orange) to
chlorophenol red in bete galactosidase assay. The red colour
intensity is measured using colorimetre. The wild type E.coli
contains LacZ gene and produce the enzyme which gives positive
result in the assay. LacI is the inhibitory gene that codes for
repressor. If the enzyme is not produced in the presence of glucose
means the repressor is activated proves LacI is present. If both
genes are present the strain is wild type. By this assay one can
easily identify difference between wild type and mutated type.
how do we determine which of the unknown strains of E.coli is LacZ-, LacI-, and which...
A. Which strain is the wild-type E.coli? Explain how you know
this.
B. Which strain contains the nonsense mutation in the CRP
protein gene? Explain how you know this.
C. Which strain contains the deletion mutation in the lac operon
operator sequence? Explain how you know this.
knowledge about the lac operon system AND knowledge Problem set about the Lac operon (these problems require knowledge about the lac operon system AND about consequences of mutations) You are working with three...
Shown below are relevant genes and sites from various E. coli strains. Note: + designates the wild-type gene or site that is fully functional, and – designates a deletion of that gene or site; lacO+ means all operators (O1, O2 and O3) are functional; assume all other genes and sites not listed are wild-type and functional (including lacA). In some cases, a plasmid containing a wild-type functional gene or site was transformed into the E. coli strain. The strains were...
Shown below are relevant genes and sites from various E. coli strains. Note: + designates the wild-type gene or site that is fully functional, and - designates a deletion of that gene or site; lacot means all operators (01, O2 and 03) are functional; assume all other genes and sites not listed are wild-type and functional (including lacA). In some cases, a plasmid containing a wild-type functional gene or site was transformed into the E. coli strain. The strains were...
As a student project, you have isolated six new mutant strains
of E. coli with altered behavior of the lactose operon. The strains
are listed in the table below, together with their phenotypes (with
regard to significant ?-galactosidase synthesis) in three specific
situations.
Columns 1 and 2 present the phenotypes of each mutant haploid
strain. In column 1, the mutant is in an otherwise wild-type
genome. In column 2, the genome also carries a nonsense-suppressor
mutation (that is not present...
2. Suppose you have six strains of E. coli. One is wild type, and each of the other five has a single one of the following mutations: lacZ, lacY, laď·0; and lach. For each of these six strains, describe the phenotype you would observe using the following assays. Explain your answers. [Notes: (1) IPTG is a colorless synthetic molecule that acts as an inducer of lac operon expression but cannot serve as a carbon source for bacterial growth because it...
In this problem you will explore how to solve problems involving partial diploid lac operon bacterial strains. Bacterial strains that are "partially diploid" have two copies of the lac operon because they aquired a plasmid carrying just the lac operon region. One copy of the lac operon region is on the recipient's bacterial chromosome, and the other copy is on the F' plasmid that was introduced into the cell by conjugation. Partial diploid genotypes are written with the F' segment...
Shown below are relevant genes and sites from various E. coll strains. Note: + designates the wild-type gene or site that is fully functional, and - designates a deletion of that gene or site; laco means all operators (Oj, 0, and Oy) are functional; assure all other genes and sites not listed are wild-type and functional (including locA). In some cases, a plasmid caintaining a wild-type functional gene or site was transformed into the E. coli strain. The strains were...
Questions for lab report: 1. Do the results show that expression of B-galactosidase is inducible? If so what is the inducer? 2. Is catabolite repression demonstrated by any of the cultures? 3. One of the strains used was wild type, and the other two were mutants. Based on your observation of the phenotypes of each strain, and your knowledge of the lac operon, which two are likely to be the mutants? What gene or region is likely to be mutated...
5. Jacob, Monod, and Pardee used various E.coli mutants to help determine how the lac operon is regulated. The descriptions of some of the mutants are listed. For each E. coli mutant determine if the lac operon would be on or off in a lactose-only environment. laci mutant: This mutant produces a super repressor that is not inactivated by allolactose. It will still stick. Operater will be off, lacO mutant: This mutant has an altered operator sequence so that the...
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....