Basic biology/physio questions. PLEASE HELP?

Question

could anyone write a sentence of two about this?

Structure of a phospholipid membrane

and

a general description of what happens when a ligand binds to a cell receptor protein?

please help

thanks.

Answer 1

a lipid is a fat molecule (fats hate h20)

a phospholipid is a fat moleucle with a phosphate attached to it (phoshate groups love protiens [because other proteins usually have a phosphate on them])

what makes it unique is that it is a bi-layer format which allows two things to happen.

first, the fat portion of the molecule always faces water (and inhibits h20 from coming in or out).  that is good because in a cell, it is important to keep the water content just "right" (osmotic homeostasis).  it also prevents a barrier for other junk getting inside.

second, the phospate portion of the bilayer allows for channels to be attached to outer (1), and inner (2), layers of the membrane.  this phosphate bi-layer allows communication from the outside of the cell to enter the inside of the cell.  

here is how is how i can show it, but it is very crude:

1

i am a lipid and i hate water and i am the extracellular membrane

i am a phosphate group and i love proteins

i am a phosphate group and i love proteins

i am a lipid and i hate water and i am the intracellular membrane

2

1=outside the cell  (extracellular membrane)

2=inside the cell  (intracellular membrane)

this answers a your first question: could anyone write a sentence or two about this?  Structure of a phospholipid membrane.  

here is an answer to your second question:  it gets more complex, as you should expect.  but it is not hard to understand.

phosphates are good at holding onto proteins. and proteins have been know to work collaboratively with h20 and fats. in fact they work well with many molecules.  but they interact best with other proteins.

i am going to assume you know that proteins have a uniqueness about themselves.  proteins bend into amazing and elegant shapes.  

and what makes science so fascinating is that of all the billions of protein shapes available amongst themselves, some are made to be together.  and when they find each other they can do amazing things.  

here is a ligand and a receptor binding, via my crude example.  

however you will notice that (3) is a ligand  trying to communicate to the inside of the cell, (4) is the receptor protein which listens to the message and delivers it internally, and (5) is the echo the ligand/receptor message sends.

                                         (3)     (3)    (3)

1

i am (4) a lipid and i(4)hate water and i am the extracellular membrane

i am a phosphate (4) group and i love proteins (4)

i am a (4) phosphate group and (4) i love proteins

i am a lipid and(4) i hate water and i am (4) the intracellular membrane

2

    ((((((((((((5)))))))))))))           (((((((((((5))))))))))))

((((((((((((((((((((((((((((((((((((5)...