<span>The ramp has to be 120 meters long.</span>
Whats the question? I think that you are missing a part of your question.
Answer:
The correct answer is b. glucose is low and lactose is present
Explanation:
Lac operons are found in bacteria and it contains one regulator gene, one promotor sequence, one operator and three structural genes. When lactose is not present in the environment regulatory gene synthesizes repressor proteins that bind to the operator and stops the expression of the lac operon.
When lactose or allolactose is present then it binds to repressor proteins and prevents the protein to bind to the operator region which results in the expression of the lac operon. So to express lac operon lactose should be present.
In presence high amount of glucose lac operon is not expressed because glucose is the easy source of getting energy than lactose so for expression of lac operon glucose should be low and lactose should be present.
<span>Surface proteins are specialized integral membrane proteins that allow communication between the cell and the extracellular space.
Membrane spanning proteins are integral proteins that span the entire phospholipid bilayer.These trans membrane proteins contains one or more membrane spanning domains as well as domains from four to several hundred residues long,extending in to aqueous medium on each side of the bilayer.</span>