Essay on Important Cell Components
Essay on Important Cell Components
Being one of the most important components of a cell, the plasma membrane, or cell membrane plays a huge role in regulating how things get in and out of cells. The plasma membrane’s unique structure enables it to let only certain molecules pass through the cell. This ability is called selective permeability. Most of the plasma membrane in most cells is made up of a phospholipid bilayer with proteins either embedded into it or sticking out from either side of the membrane. The heads of the phospholipids absorb water from the extracellular environment while the tails of the phospholipids repels it. This system helps the membrane regulate the flow of water in and out of the cell, and is also responsible for letting in hydrophobic or water repelling molecules into and out of the cell as well.
Molecules may enter the cell via two main kinds of transport: active and passive. Passive transport is the movement of molecules through the cell membrane that requires no energy. The molecules passing through the membrane move from the area of the higher concentration to the area with a lower concentration. In other words, the molecules move along the gradient and therefore do not need energy to help them move through the membrane. Diffusion is another word for passive transport and is categorized by two ways: facilitated and simple. In simple diffusion, the molecules are either hydrophilic or small enough to pass through the phospholipid bilayer without any assistance. In facilitated diffusion, proteins embedded in the cell membrane, provide a doorway for particular solutes to go through. Even though the proteins move in order to make openings for solutes, this process does not use any energy.
Water is crucial for the survival of cells. Water is able to diffuse through the membrane by a method of passive transport called osmosis. Osmoregulation is the control of the water balance in cells. The amount of water in and out of cells has a great effect on the concentration gradient inside and outside cells. When there is more water inside the cell and more solutes outside the cell, the cell is hypotonic to the extracellular fluid. In other words, the cell is in a hypertonic solution. As a result of this, more water molecules leave the cell...