The bacterium, e. coli prefer to consume glucose. if, however, there is no glucose present, they will utilize lactose as an energy source. which of the following is the regulatory mechanism occurring when there is no glucose, but there is lactose?
a. activators initiate gene expression
b. rna cannot bind to the promoter
c. no lactose metabolism genes are transcribed
d. rna polymerase is blocked
e. the repressor protein binds to the operator region

Option A

Explanation:

Usually, the cells first is able itself to regulate the usage of sugar type that yields highest growth rate and then consume sugar with lower growth rate and so on.  

Considering this scenario E.Coli first consumes glucose and then lactose however both the sugar will result into diauxic growth

cAMP is responsible for activating the enzyme involved in metabolism of non-glucose sugars. The CRP protein of cAMP receptor is mainly responsible for activating the non-sugar metabolism enzyme . Along with this,  cognate sugars also expresses gene

Hence, option A is correct

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.

bacteria could be both, harmful and to us. harmful bacteria could make us sick and probably even by getting the chances of getting a disease, but good bacteria fight it off with your immune system. there is always bacteria everywhere we go. we need to make sure to wash our hands after using the restroom, before eating, after eating, after petting an animal too. so you see, bacteria is everywhere and is harmful or . i hope this . : ) : ) : )