Widened margins does not occur at the continental margin
Microtubules originate on the centre of the cell taking the positive end to the periphery of the cell, while the negative end remains turned to the centre of the cell. The melanosomes move along these microtubules using motor proteins desiganted kinesins and dyneins. The kinesins are responsible for moving the melanosomes to the positive end of the microtubule (periphery of the cell) generating dark-colored cells, whereas dyneins move the melanosomes to the negative end of the microtubule (centre of the cell) generating light-colored cells.
Animals and plants need to get rid of carbon dioxide gas through a process called respiration. Carbon moves from fossil fuels to the atmosphere when fuels are burned. When humans burn fossil fuels to power factories, power plants, cars and trucks, most of the carbon quickly enters the atmosphere as carbon dioxide gas.