Anyone good at Biology?

Anyone good at Biology?

I apologise profusely for the post I am about to make, but I'm confused, and last time I made a post like this, I received adequate help.

Vitamins C and D take different routes across the plasma membrane. Vitamin C is water-soluble, while Vitamin D is lipid-soluble.

I have to "Explain how the structure of the plasma membrane determines the route taken by each of these vitamins".

Am I right in saying that Vitamin D cannot pass through the phospholipid bilayer, because it would be dissolved, and therefore must pass through via a transport protein, and that Vitamin C, being water-soluble, could not pass through a transport protein as they're hydrophilic, and therefore must pass directly through the bilayer?

Thanks for any help, apologies to anyone that reads this and doesn't have a clue, bit desperate though!

geek

Thanks for your ever-useful input on this Sasha...

Google

No. I was shit at it actually.

Re: Anyone good at Biology?

Apologies for this reply, but:

I remember doing this!!

But I can't remember exactly if the above is right. It does sound it, as I'm sure that vitamin D did have to go via the transport proteins... unsure about vit C tho.

It's been almost six years since I did that at uni so apologies for the not remembering thing...

Re: Re: Anyone good at Biology?

That's fine mate, thanks for your reply. If Vitamin D passes through via transport proteins, then Vitamin C must pass through the bilayer. Just needed to know if I had them the right way round

Cheers fella.

I think if Vitamin D is lipid-soluble that it can pass through the plasma membrane, It works like a steroid, whilst vitamin C requires a membrane transfer via a protein

could be wrong though

I thought vitamin c was lipid-soluble?

Because vitamin c's water-soluble?

Fuck, I did get them the wrong way round. Balls.

Oh my god yeah i am! I can help you!....

Just to add to that and add to my confusion - vit c also requires a plasma protein to transport it.

I give up, I can't remember what day it is, let alone this...

And you said I was failing

........NOT

While we're here, does anyone know why glucose molecules can't pass through a phospholipid bilayer?

if I remember rightly vitamin c uses the same plasma membrane receptors as glucose

vitamin d is absorbed passively in the small intestine

Now you're beginning to lose me. Is glucose only absorbed via active transport? Or can it be diffused? :spangled:

Because it's a large uncharged polar molecule. It requires a transport molecule. :lecture: :spangled:

mainly cos it's just too big
think it gets in via cotransport, where a transport protein binds to h+ ions (from a proton pump) and glucose
:spangled:

H+ and Na+ isn't it?