Question

The distribution of melanosomes in cells is tightly regulated in animals that rapidly change color. Dark-colored cells have melanosomes scattered throughout the cytoplasm while light-colored cells have them aggregated near the nucleus. How could cells use microtubules and motor proteins to change the distribution of melanosomes?

Select all that apply.

Kinesin would be used for moving melanosomes back to the nucleus in light-colored cells.

Microtubules originate near the nucleus of animal cells, and the positive ends project outward.

Dynein would be responsible for moving melanosomes outward to generate dark-colored cells.

Dynein would be used for moving melanosomes back to the nucleus in light-colored cells.

The melanosomes move along microtubule tracks using motor proteins.

Kinesin would be responsible for moving melanosomes outward to generate dark-colored cells.

Microtubules originate near the cell wall of animal cells, and the positive ends project outward.

Answer 1

Microtubules are synthesized from the nucleus to the cell membrane with the minus end at the beginning of it (center of the cell) and the plus end at the end (near cell membrane).

Light-colored cells are the result of the movement of melanosomes due to dynein action, which transports molecules (melanosomes in this case) towards the minus end of microtubules at the center of the cell. Kinesin transports molecules it in the opposite direction, i.e, moving melanosomes from the nucleus towards the cell edge generating dark-colored cells.

Both of these, Kinesin and Dynein molecules are motor proteins.