Question

Note whether in the following strains of E. coli, B-galactosidase will be:

(A) Abundant in both the presence and absence of lactose

(B) Abundant only in the absence of lactose

(C) Abundant only in the presence of lactose

(D) Abundant only in the presence of sucrose

(D) Absent in both the presence and absence of lactose

Can you answer and explain these please?

What is the correct gene order and which 2 genes are most closely linked? (4 Points) o+at at 6. Note whether in the following strains of E. coli, B-galactosidase will be: (7 Points) (A) Abundant in both the presence and absence of lactose; (B) Abundant only in the absence of lactose; (C) Abundant only in the presence of lactose; (D) Abundant only in the presence of sucrose; or E) Absent in both the presence and absence of lactose. Strain 1: Wild-type Strain 2: o(c) Strain 3: i(s) p(-) Strain 4: p) o(e) Strain 5: i(s) o(c) /i(+) 0(+) J Strain 63(-) p(+) / i(+) p(-) Strain 7: i(-) p(+) o(c) / İ(+) p(-) o(+) EXTRA CREDIT. (3 Points) A generalized transducing phage is used to transfer genes from a his(+)met(+)phe(+) donor strain of E. coli to a his(-)met()phe() recipient strain. When transductants on a medium containing histidine and methionine are tested for growth on other media, many more co found on media supplemented only with histidine than on media supplemented only with methionine order and which 2 genes are most

Answer 1

B-galactosidase will be abundant only in presence of lactose because lactose induces its formation while glucose inhibits it.

Strain 1 : wild type, shows B-galactosidase

Strain 2 : o(c) - constitutive operon - shows B-galactosidase

Strain 3 : no B-galactosidase, p(-) - no promoter

Strain 4 : no B-galactosidase

Structural Genes: Z+ ability to produce ß-galactosidase. Z- = lacks ability to produce β-galactosidase. Y+- ability to produce permease (uptake of inducer). Ylacks ability to produce permease (uptake of inducer). A ability to produce acetylase. A lacks ability to produce acetylase. Regulator gene: 1+inducible--produces normal repressor protein that has affinity for the 1-(also「) = constitutive-repressor has altered affinity for the operator-can not bind to ISsuperrepressed--altered affinity for inducer-The repressor cannot operator and the inducer. the operator. dissociate from operator region. Q refers to quantity. It is a mutation in the lacl gene promoter that results in an increased number of repressor molecules in the cell. Operator: O+wild type, binds repressor. Occonstitutive--altered nucleotide sequence--repressor CANNOT bind to the 0constitutive--deletion in repressor BINDING SITE, repressor cannot bind. O°deletion in the proximal area of the operator that includes part of the operator site. promoter. Polymerase cannot bind at all CRP- or pAltered or no CAP binding site. The rate of polymerase binding is lowered and transcription is reduced or goes to zero wild type catabolic activating protein mutant catabolic activating protein will not complex with cAMP, thus rate of polymerase binding is lowered. CAP+ CAP- - =

Strain 5 : shows B-galactosidase

Strain 6 : shows B- galctosidase

Strain 7 : shows B- galactosidase