Differentiate between carriers and channels.

CARRIERS:

1. Carriers are proteins that transport molecules down their electrochemical gradient. Hence, they do not require energy.
2. Carriers protein transport molecules.
3. Carriers proteins flip between two conformations.
4. Carrier proteins can mediate both active and passive transport.
5. Solute molecules are bound to one side and released from the other side.
6. Have low transport rates of 10^4 ions per second.
7. Consists of alternative solute-bound conformations.
8. Carrier proteins are glycoproteins.
9. Carrier proteins are synthesized in the free cytoplasmic ribosomes.
10. Carrier transport water soluble molecules across the membrane as well as the insoluble molecules.
11. Specificity of carrier proteins is due to an ion selectivity filter.
12. E.g., of Carrier protein mediated active transport : Na+/ K+ ATPase and SR Ca2+ ATPase

CHANNELS:

1. Channels involve proteins that transport molecules against their electrochemical gradient, hence requires energy provided by ATP hydrolysis.
2. Channel protein transport ions.
3. The position of channel proteins is fixed.
4. Channel proteins can mediate only passive transport.
5. Solute molecules diffuse through the pores.
6. Have high transport rates of 10^8 ions per second.
7. Channel proteins do not bind with solute molecules it transport.
8. Channel proteins are lipoproteins.
9. Channel proteins are synthesized in the ribosome bound to rough endoplasmic reticulum.
10. Channel transports only water soluble molecules across the membrane.
11. Specificity of channel proteins is due to specific binding sites to which the solute molecules bind.
12. E.g., of channel protein mediated passive transport: Voltage gated channel and Ion gated channels.