Question

How do carrier proteins work?

Answer 1

Carrier proteins help to transport substances from one side of the membrane to the other. Carrier proteins are very specific for the ions, molecules or group of substances they carry.

Complete answer:
Carrier proteins can be defined as the transport proteins that are specific for an ion, molecule or group of substances. Carrier proteins help in both passive and active transport. Carrier proteins work by changing their shape during the transport of ions or molecules across the membrane. Carrier proteins are found in the cell's membrane and also in the membranes of internal organelles like mitochondria, chloroplast, nucleolus and others. Carrier proteins possess a “binding site” which binds only to the substance they are supposed to carry. Once the carrier proteins have bound to an adequate quantity of its target substance, the carrier protein will change the shape to transport the substance from one side of the membrane to the other.

For example, the carrier protein known as sodium-potassium pump binds to ions on one side of the membrane, then changes shape to carry them through to the other side without opening the channel.

Some carrier proteins utilize diffusion gradients for their substrates to pass down, making them a form of passive transport. Some carrier proteins also require energy in the form of

ATP during the transport of the substance against the diffusion gradient, making them the form of active transport.
Some of the common purposes served by carrier proteins include:
1)Creating ion gradients which allow nerve cells, mitochondria and chloroplast to function.
2)Transporting large molecules such as sugars and fats in and out of cells.

Note: Carrier proteins allow the movement of molecules to only one side of the membrane at a time. Carrier proteins help both in active and passive transport and help in the transport of large molecules in and out of cells