The Student Room Group

Why does the aqa alevel specification say that glucose transports through a channel

Isn’t it carrier
So why does it say that for homeostasis that insulin increases the number of channel proteins present on the membrane.
Hello young lady/man,

Sorry you have had no help for so long!

It is inevitable inherently for some confusion to be introduced when massively simplifying matters for your level. So if you are visiting :colondollar:, don't panic you are not the only one!

There are a number of different proteins involved in transport of glucose across membranes; some do it by active transport, others by facilitated diffusion together with Na+ e.g. GLUT1 in the intestine, GLUT5 for fructose [sorry diverting slightly], etc depending which organ/tissue we are talking about e.g. the transporters are different in the kidney where reabsorption of glucose occurs in the proximal convoluted tubule.

My advice would be not to get bogged down with trivial detailed items such as these BUT RATHER to understand that insulin acts in several ways to reduce blood glucose:-

a] it promotes glycogenesis [increases conversion of glucose to glycogen]
b] It inhibits glycogenolysis [breakdown of glycogen into glucose]
c] It inhibits gluconeogenesis [breakdown of a.a.-s into glucose by deamination [neo = new so "new" glucose [from protein effectively]]]
d] it promotes entry of glucose into cells [hence less in blood, happy?]
e] it inhibits reabsorption of glucose in the proximal convoluted tubule of the kidney.

Saying all these SEPARATE but RELEVANT points is what earns marks, not quibbling about subtle terminology, yeah? BEAR IN MIND: what counts is mark, mark, mark!

Best of luck & be safe!

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