Question

Carrier proteins are involved in the
(a) Active transport of ions
(b) Passive transport of ions
(c) Water transport
(d) Both (a) and (b)

Answer 1

Hint: This involves transport of ions across the biological membranes. This transport occurs in both the directions that means against and towards the direction of concentration gradients.

Correct answer:
Carrier proteins are involved in both the active and passive transport of ions. The proteins that carry substances across the biological membrane are known as carrier proteins. At one time the carrier proteins are open only to one side of the cell membrane. In active transport a substance needs to be carried against its concentration gradient in a direction it would not normally flow. Also in the process of facilitated diffusion which is a type of passive transport carrier proteins is used. A typical binding site is present on carrier proteins which bind only to the substance that is supposed to be carried by them.

Additional Information:
-The carrier protein binds to the ions on one side of the membrane, after that it changes shape to carry them through the membrane to the other side without opening a channel. For example sodium potassium pump.
-The ability of carrier proteins to change its shape after binding with ions makes it useful for active transport.
-During active transport the carrier protein binds with ATP, and uses its energy to pump the ions across the cell membrane in opposite directions.
-In passive transport a carrier protein valinomycin binds with potassium and carries it across the cell membrane towards its concentration gradient, in the direction where the potassium tends to move.
-The passive transport does not require energy to occur because here movement of ions takes place towards or in the direction of concentration gradients.
-Water transport is that process in which goods, people, etc move barges, boats, ships or sailboats over a sea, ocean, lake, canal, river, etc.

So, the correct answer is,' Both (a) and (b)' .

Note:
-The carrier protein helps in creating ion gradients which allow nerve cells, mitochondria, and chloroplast to function.
-Valinomycin is a carrier protein involved in passive transport of ions towards the concentration gradient.
- In active transport energy is needed whereas in passive transport there is no need for energy for the process to occur.