Examples of active transport
- Sodium-potassium pump. It is a mechanism of the cell membrane that allows, through a transporter protein, to expel sodium from inside the cell and replace it with potassium, maintaining ion gradients (low sodium and abundant potassium) and convenient electrical polarity.
- Calcium pump. Another transport protein present in the cell membrane, allows calcium to be carried against its electrochemical gradient, from the cytoplasm to the exterior.
- Phagocytosis. The white blood cells that allow us to defend the organism incorporates, through sacks of its plasma membrane, the foreign particles that we will later expel.
- Pinocytosis. Another phagocytic process proceeds through invaginations in the membrane that allow the entry of environmental liquid. It is something that the egg does during its maturation.
- Exocytosis. Contrary to phagocytization, it expels elements of the cellular content through membranous sacs that move outward, until they fuse with the membrane and open to the outside. This is how neurons communicate: transmitting ionic contents.
- HIV infection. The AIDS virus enters cells by taking advantage of their membrane, binding to glycoproteins in their outer layer (CD4 receptors), and actively penetrating inside them.
- Transcytosis. A mixture of endocytosis and exocytosis, allows the transport of substances from one medium to another, for example, from the blood capillaries to the surrounding tissues.
- Sugar phosphotransferase. A typical process for certain bacteria such as coli , which consists of chemically modifying the substrates inside them to attract others by covalent bonding and thus save a great deal of energy.
- Iron catchment. Many bacteria capture iron by secreting siderophores such as enterobactin, which binds to iron to form chelates and is then affinity-absorbed into the bacteria, where the metal is released.
- LDL uptake. This lipoprotein with cholesterol esters is captured cellularly thanks to the action of an apoprotein (B-100) that allows its entry into the membrane and subsequent decomposition into amino acids.
Read Also: Active Vs Passive Transport
