How various mechanisms by which substances cross the cell membrane

Homeostasis is essential to the cell’s survival. The cell membrane is responsible for homeostasis. The membrane has a selective permeability which means what moves in and out of the cell is regulated. Amino acids, sugars, oxygen, sodium, and potassium are examples of substances that enter the cell. Waste products and carbon dioxide are removed from the cell. All of these substances cross the membrane in a variety of ways. From diffusion and osmosis, to …

…is hydrolyzed and the phosphate group is transferred we call it phosphorylation. In review, substances cross the cell membrane in two different ways: passive and active transport. Passive transport includes osmosis, diffusion, and facilitated diffusion. None of these techniques use energy. Active transport includes endo and exocytosis, sodium-potassium pumps. and phosphorylation, all of which expend energy to transport substances across the cell membrane. The cell has the ability to regulate what crosses its cellular boundaries.