Proteins Lipids Organelles

I got a lipid bilayer

Its permeable but selective

Simple diffusion, no confusion

Small nonpolar just flows through

02 and steroid hormones

Have no problem passing through

But polar molecules

Need some help to diffuse

That’s where membrane proteins

Come in to facilitate transport

Ions with a charge can’t make it

Through the hydrophobic interior

There are channels and transporters

Both are highly selective

Open in response to ligand,

Voltage or mechanical change

(CHORUS)

Come to my membrane

Yeah we gotta transport

Not just anything

Can go through my bilayer

Can you just diffuse it

No you got a charge

I gotta facilitate you

We got that TRANSPORT

Can be passive or active

Lucky for ions we got channels (we got channels)

Lucky for ions we got pumps (we got pumps)

Passive goes down your gradient

Based on concentration and voltage

A ligand binds onto a channel (onto a channel)

It opens up and passes through (and passes through)

(VERSE 2)

I’m talking ‘bout membrane potential

We got charges on both sides

There’s also ion concentration

Formed by protein transportation

Add it all to

Electrochemical gradient for that ion

This will provide stored energy for the cell

Low sodium inside the cell

But high potassium

It’s just more negative in here

This helps the cell function

Is it in (is it in)?

Is it out (is it out)?

What direction is the gradient?

Then that’s where the ion will flow

(CHORUS)

Come to my membrane

Yeah we gotta transport

Not just anything

Can go through my bilayer

Can you just diffuse it

No you got a charge

I gotta facilitate you

We got that TRANSPORT

Can be passive or active

Lucky for ions we got channels (we got channels)

Lucky for ions we got pumps (we got pumps)

Active goes against your gradient

Energy required, where’s the ATP?

Or there’s a coupled pump you see (oh you see)

It sends two molecules using built up energy

(BRIDGE)

But then there’s just this one pump

It creates the most important

Electrochemical gradient

Sodium Potassium ATPase

Driven by ATP

3 Sodiums out

2 Potassiums in

That’s how the gradient forms

Coupled pumps,

Symports and antiports

Use this gradient to move their molecules

(CHORUS)

We got that TRANSPORT

Can be passive or active

Lucky for ions we got channels (we got channels)

Lucky for ions we got pumps (we got pumps)

After this gradient forms

Gotta get back to the resting potential

Potassium leak channels open up (they open up)

They balance membrane gradients (they balance them)