Answer:
a. + glucose, + lactose = On
b. - glucose, - lactose = Off
c. + glucose, - lactose = Off
d. - glucose, + lactose = On
Explanation:
Lac operon has both types of control, repressible and inducible.
Whenever glucose level is low in the cell, an enzyme known as adenylyl cyclase raises the level of cAMP which forms a dimer with CRP protein and they both act as activator of lac operon and cause expression.
Apart from this, when lactose is present in the cell, β-galactosidase enzyme metabolizes lactose to form allolactose which causes allosteric repulsion in the lac repressor and causes its removal from the operator. As soon as repressor is removed lac operon gets activated.
In wild type lac operons, the expression of lac operon occurs when glucose level is low in the cell and lactose is present but in this mutant presence or absence of glucose will not make a difference because CRP will bind Plac promoter independent of cAMP level i.e. activator CRP will work even in high glucose concentration. If lactose is present then lac operon will always express so in option 'a & d' lac operon will express but in option 'b & c' it will not express.
<span>Reticulocytes are immature red blood cells.
Red blood cells that haven't fully developed, yet.
When our bodies lose a large amount of blood,
we rapidly produce reticulocytes,
so that our bodies can quickly replenish their red blood supplies.
And obviously, when we donate blood, we lose blood.</span>
<span>c. euglena have chloroplasts
</span><span>
Chloroplasts are organelles that are responsible for the photosynthetic functioning of an organism.Photosynthesis is the process by which an organism uses the photons to produce energy. These organisms uses the sun, together with the acquired resource of water and carbon dioxide to create sugar and process into energy. </span>
D -<span>the start of glaciation and climatic changes</span>
The medical term for this is the endicrine.
