Can anybody help me with this please? These are multiplechoices. I have answered

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Can anybody help me with this please? These are multiplechoices. I have answered them already, but just wanted to check if theyare correct. Please answer only if you know for sure. I willdefinately rate high for those who answer(good ones). Thanks!
1. Which of the following is true regarding regulation of thelactose operon in E. coli?

Glucose is an inducer.
Inducers function mainly by activatingrepressors.
When CRP binds cAMP, the CRP-cAMP complex cannot bind theDNA promoter.
When the repressor is bound to the operator, transcriptionis inhibited. 2. A mutant strain of E. colishows minimal beta-galactosidase activity when cultured inLB-glucose broth + IPTG, but high beta-galactosidase activityfollowing the addition of cAMP. The most likely genotype of thisE. coli strain is:

lacI¯ cya+ crp+
lacI+ cya+ crp+
lacI+ cya¯ crp+
lacI+ cya+crp¯ 3. For each of the following (A-C), indicate whether itdirectly interacts with the promoter, operator, or neither regionof DNA in the lactose operon.

A. lacI repressor protein
B. IPTG
C. Chloramphenicol Can anybody help me with this please? These are multiplechoices. I have answered them already, but just wanted to check if theyare correct. Please answer only if you know for sure. I willdefinately rate high for those who answer(good ones). Thanks!
1. Which of the following is true regarding regulation of thelactose operon in E. coli?

Glucose is an inducer.
Inducers function mainly by activatingrepressors.
When CRP binds cAMP, the CRP-cAMP complex cannot bind theDNA promoter.
When the repressor is bound to the operator, transcriptionis inhibited. 2. A mutant strain of E. colishows minimal beta-galactosidase activity when cultured inLB-glucose broth + IPTG, but high beta-galactosidase activityfollowing the addition of cAMP. The most likely genotype of thisE. coli strain is:

lacI¯ cya+ crp+
lacI+ cya+ crp+
lacI+ cya¯ crp+
lacI+ cya+crp¯ 3. For each of the following (A-C), indicate whether itdirectly interacts with the promoter, operator, or neither regionof DNA in the lactose operon.

A. lacI repressor protein
B. IPTG
C. Chloramphenicol 2. A mutant strain of E. colishows minimal beta-galactosidase activity when cultured inLB-glucose broth + IPTG, but high beta-galactosidase activityfollowing the addition of cAMP. The most likely genotype of thisE. coli strain is:

lacI¯ cya+ crp+
lacI+ cya+ crp+
lacI+ cya¯ crp+
lacI+ cya+crp¯ 3. For each of the following (A-C), indicate whether itdirectly interacts with the promoter, operator, or neither regionof DNA in the lactose operon.

A. lacI repressor protein
B. IPTG
C. Chloramphenicol

Explanation / Answer

(1) The   last option is true , i.e. when repressor is   bound to the operator , transcription is inhibited , because the    RNA Polymerase is not able to   recognise   the promoter . (2) Answer   should be third   as   lacI+cya¯ crp+ , as  lacI codes   for   the  repressor   protein   which  inhibits   the    expression  of   the   structural   genes .But   cya gene encodes for  cAMP   which   upon binding with CAP   enhances  expression    of    the    structural    genes . The   cya-  mutants    are   unable to   code for   CAMP  &   upon   addition   of   cAMP    show   normal    functioning . ( 3) (a)   lacI  repressor   protein   binds  to   the   operator.         (b) IPTG (Isopropyl- -D -thiogalactosidase )  binds   to the   repressor .        (c)Chloramphenicol    has an action only in the   cytoplasm   as it   prevents   the   translation,therefore   it   does  not   bind   to   the   any DNA region .

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