Aresearcher has identified a mutation in mouse cells that results in these cells having abnormally low levels of pax3 (a gene involved in muscle development) gene transcription. he determines that this is a result of a mutation affecting a promoter-proximal element. this mutation:
a. occurs upstream of the pax3 promoter.
b. may occur in a ccaat box. may occur in a gc-rich box.
c. may affect the ability of regulatory proteins to associate with pax3
d. all of the answers are correct.

the right is separation by density .

take the blood which is a good example of a heterogeneous mixture.

blood is a vital liquid in our body, which transports oxygen from the air to our lungs so we can breathe. it is also used to eject wastes, such as carbon dioxide, to bring cells and molecules of the immune system to the tissues, and to spread hormones throughout the body. it corresponds to plasma, red blood cells, white blood cells, platelets and hemoglobins combined.

in medical tests centrifugal force is used to separate the different components of the blood.

in general, the centrifugation will allow to separate and analyze the different components of the blood, to know if the rate of white blood cells in the blood of a patient, for example, is normal, and therefore to know if his system immune is integrity.

under the action of centrifugal force, the solid components in the blood are drawn to the bottom of the tube in which the blood is contained. the centrifugal force then acts as an accelerated settling. it separates plasma from red blood cells and white blood cells.

your awnser is a.gap junctions