Biology : Cell Membrane Transport

2664 Words Oct 9th, 2014 11 Pages
Cell Membrane Transport
Ard Orpilla
Zoology 2011 Section 16
Manisha Rao
October 6, 2014 Introduction
Cells are the basic units of life. Everything alive consists of cells. In order for cells to perform their basic functions, it has to continuously seek homeostasis. This is done by structures within the cell. A structure within the cell is the plasma membrane, which regulates what enters and exits the cell. The cell membrane contains a phospholipid bilayer which causes the cell to have selective permeability; “allowing transport of some chemicals but not others” ( ). Specifically, the phospholipid bilayer allows for the movement of water, oxygen, and carbon dioxide. Conversely, it is not permeable to ions or polar chemicals. The phospholipid bilayer is in possession of hydrophilic and hydrophobic regions, which are the polar heads and tails, respectively. This is important because the head attracts water while the tail repels water, thus regulating the substances entering and exiting the cell. When substances pass through the plasma membrane, they use passive or active transport. Whether either transport type is used is determined by the concentration gradient, which is the difference of concentration between areas. In an active transport, the cell must use adenosine triphosphate, or ATP, which is produced by the mitochondria of the cell and is energy used by the body, because the substance is moving from a lower concentration gradient to a higher…
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