Active Transport is a transport mechanism that consumes energy for the movement of ions or molecules through plasma membrane. The mechanism occurs from low consentration solution to high concentration solution.
Active transport is influenced by electric charges inside and outside the cell. Electric charge of a cell is especially determined by natrium (Na+), kalium (K+) and chlor (Cl-)ions. The movement of natrium and kalium ions is conducted by sodium and potassium pump (Na+ and K+ pump) by using energy obtained from ATP. The sodium-potassium pump moves Na+ ions from inside of the cell to the outside of the cell and moves ion K= from outside of the cell.
The presence of ion K+ and Na+ in organism’s body gives a great advantages, some of which are as follow:
- The high concentration of K+ ions is very importand in synthesis protein, glycolysis, photosynthesis, and other vital processes.
- Na+ and K+ ions play role in controlling osmosis.
- Na+ and K+ ions are necessary to acceleration active transport for other substances, i.e. glucose and amino acid.
The example of active transport through plasma membrane is glucose transport. The substance is carried actively by cell through protein membrane by using activated energy. The energy is resulted from ATP breaking down producing ADP, phosphate group, and energy. The energy obtained is used to bind phosphate group to glucose to form phosphate glucose compound. The last compound is the one that is able to pass through plasma membrane because it binds the activated energy.
Endocytosis and Ectocytosis
Endocytosis is a process to put in substances through membrane, while ectocytosis is a process to put out substances through membrane. The prosess mostly occurs in unicellular organism, such as amoeba, paramecium, and certain cells of vertebrate (white blood cells).
Endocytosis occurs when animal cells put in food mater, or white blood cells capture germs (phagocytosis).
Ectocytosis in cytoplasm is usually conducted by some organelles, i.e. vacuole or granule. Ectocytosis occurs when cells excrete waste or secrete, the examples are gland cell or secreation cells.