Question

if anyone could explain how to do this? Genuinely have no idea where to start

RG .....LOGSG-1 SG2 SG3 1_Repressor_ E- E 2 - E -3 Precursor - > Cmpd. - > Cmpd.- > Cmpd. from Medium In the above diagram I, 2, E-3 represent different enzymes controlling three different steps in the biosynthetic sequence for the production of compound C. and RG-regulator gene, OG operator gene, and SG = structural gene. a. Referring to the diagram above identify the components of the system which would interact to increase the concentration of compound C, if the sequence were controlled by induction (eg, the repressor and E-1). b. If the diagram above represented a system involving coordinated enzyme repression describe the effect on the concentration of compound Cir the repressor was defective and unable to combine with the effector molecule. C. If the diagram above represented a system controlloed by a positive activator protein what components of the system would interact to increase the concentration of compound C? 6. A hypothetical model of interrelated gene circuits is given below. R.G. - regulator gene: O.G. - operator gene; and S.G. = structural gene. If the repressor A is active at the time of its production and repressor B is inactive at the time of its production, describe the result that the addition of effector A would have upon structural gene-4. OG-2 SG- 2 1 RGLI Repressor A Effector A L OG-3 ISG-3 RG-3 _Repressor B LOG- 41 SG-4

Answer 1

5.a. If the system was controlled by induction, then the inducer (or the effector) will interact with the Repressor. Due to this the repressor cannot bind and repress the OG anymore, which will lead to transcription and increase in concentration of compound C.

5.b. If the repressor is defective and is unable to bind to the effector molecule, then it will never leave the OG and will be continuously attached with the OG. This will lead to no production of compound C even in presence of induction. Concentration of compound C will be minimal or zero.

5c. If the system was controlled by a positive activator protein then that activator protein will interact with the OG to increase transcription and thereby increase concentration of compound C.

5d. Effector A binds and inactivates Repressor A, which was active till then. In absence of active repressor A, OG3 is derepressed, and gets activated. This leads to the transcription of RG3 and eventual production of repressor B, which can repress OG4. But according to the question, repressor B is inactive at the time of its production. Thus OG4 and SG4 will be successfully transcribed.