test.

[CrazyChik]

i did!!!!! a couple days ago but u woul;dent give me any so i stolded it! xD

You tried to steal it without asking me for some first!!!!

 

[jacensolo3]

You tried to steal it without asking me for some first!!!!

nu uh i asked then stole! and say hi to lauren or i will start stealing other stuff from you!

 

[CrazyChik]

nu uh i asked then stole! and say hi to lauren or i will start stealing other stuff from you!

Pffffft.

Hey Lauren!

 

[marypops!]

I don't see the point in this homework... I'm almost copying what I have written on the handout to everyone word for word, because I can't describe it in any other way...

 

[CrazyChik]

I'm off to sleep guys.
Make sure Georgie doesn't stay up too late for me.
xD

 

[marypops!]

Goodnight.

TINKERBELL'S BEEN RELEASED!!! I forgot about that...

 

[marypops!]

Whoops, wrong about that

It's in 2 weeks time.

 

[StitchfansJr]

woaaah, this thread is already at 12 pages? xD

 

[marypops!]

Yup

Simple diffusion refers to a process whereby a substance passes through a membrane without the aid of intermediary. However, substances with a stong positive or negative charge and large molecules can't cross cell membranes using simple diffusion. To get in and out of the cell, they use a specialised form of diffusion called facilitated diffusion, a form of passive transport facilitated by transport proteins. It involves proteins in the membrane that allow only certain substances to move through their concentration gradient.

They might be channel proteins, which form pores throughout the membrane. Each type of channel proteins will only allow one particular type of molecule through, depending on it's shape. For example, there are sodium ion channels, which will only like sodium ion molecules through. Some channels only open when a certain molecule is present or an electrical charge passes through the membrane, like during the passage of nervous impulses along neurones.

Another form of facilitated diffusion depends on the carrier molecules floating on the surface of the membrane. They are found on the outside surface of the membrane when a substance is to be moved into the cell, and on the inside for transport out of the cell. The protein carriers are specific for particular molecules, depending on the shape of the protein carrier and the substance to be carried. Once a carrier has picked up a molecule, it rotates through the membrane to the other side, taking the molecule with it, before releasing it. The movement takes place because the carrier changes shape once it carries something. The process can only take place down a concentration gradient, from high concentration, to low concentration. It doesn't use energy, so it's considered a type of diffusion. For example, red blood cells have a carrier to help glucose move into the cells quickly.

How fun is facilitated diffusion?!?

 

[Babyjustrun]

Tis eerily quiet..

 

[wdwllamadancer]

hello

 

[AmandaSparks730]

*yawns*

Not looking forward to Friday.

 

[Babyjustrun]

Friday will be awesome for me.
Grade rep speeches are that day, so I either miss period 1 or 2.

 

[AmandaSparks730]

Fridays are usually cool. But due to Junior testing, we have period 7 for an hour and a half.

Of COURSE, that just happens to be Geometry.

Grrrrr.

 

[Babyjustrun]

I'd hate that.
My longest class is an hour and .. 10 minutes.

 

[AmandaSparks730]

My longest period is 70 minutes (aka "long period" or lunch period).

 

[Babyjustrun]

Lunch is only an hour here.

I wish first wasn't longer, I hate english class.
It sucks hardcore.

 

[AmandaSparks730]

It's really 20 minutes each lunch, or so...4 lunches...

 

[Babyjustrun]

Ah okay.
I would die with only 20 minutes for lunch.
I have a routine at lunch.

 

[AmandaSparks730]

It's pretty bad if your class is in the 800 wing (English), which is the furthest away from the cafeteria. By the time you get down there, you've wasted 3-5 minutes.