Question

1. Describe the transport of glucose across the membrane. What is the name of this type of transport? It is concentration-dependent? Is energy required to drive this type of transport?

Answer 1

Glucose is a large molecule ie ; a six carbon molecule. So it is difficult to be transported across the membrane through simple diffusion.

A special type of diffusion known as facilitated diffusion,is used here.

Facilitated diffusion is a type of diffusion that requires a special type of protein known as the carrier protein to transport the molecule across the membrane. They are highly selective and the transport rate reaches a maximum when all the protein transporters are being used or in other words the transport is said to be saturated. It allows cell to select substances for uptake and selective to inhibitors that react with protein.

A concentration gradient must be already be present for molecule to diffuse even if facilitated by the protein. Hence they do not set up a concentration gradient.

This transport occur without the expenditure of ATP energy.