:)

Question 1

Describe the process of neurotransmission

Answer 1

-70:
•Stimulus, a ligand binds to a ligand gated channel causing conformational change and it to open.
•This allows a flow of Na+ inside

-55:
•Threshold, the Na+ voltage gated channels open all together allowing a mass flow of Na+ ions inside.
•This depolarises the membrane

+30:
•This is reached very quickly
•K- gated channels open and sodium gated channels close due to the mass amount of positive ions inside the cell. Conformational change
•potassium gated channels remove the potassium ions
•This repolarizes the membrane

-90:
•Both channels are closed and sodium potassium pump can reestablish the normal potential, by pumping 3Na+ out of the cell and 2K- into the cell
•This is called the re-factory period

-70:
Membrane is at its resting state

Question 2

How do transporter transport molecules across the membrane

Answer 2

By changing confirmation

Question 3

Name the two types of transporter

Answer 3

Facilitated and active

Question 4

Describe facilitated transport and give an example

Answer 4

Transporter proteins change confirmation to allow a molecule pass through the membrane. Occurs passively

•Glucose

Question 5

Describe active transport and give an example

Answer 5

Require energy to bring about conformational change of the protein.
Hydrolysis of ATP may provide energy for this process

•sodium potassium pump

Question 6

Why are transporter and channel proteins beneficial

Answer 6

Allows control of ion concentrations and concentration gradients

Question 7

What does the Na/K do

Answer 7

Transports ions against a concentration gradient using energy from ATP, so active transport

Question 8

Name 2 functions of the Na/K pump

Answer 8

• maintaining osmotic balance in animal cells

* generation of ion gradient in kidney tubules

Question 9

Describe the process of the Na/K pump

Answer 9

1) involves intrinsic proteins that span the membrane
2) 3 sodium ions bind to the carrier protein on the cytosol (inside) side of the membrane
3) at the same time, the carrier protein receives a phosphate from ATP and is phosphorylated
4) this causes conformational change of the carrier protein. With its new shape the protein pumps 3 Na ions through the membrane
5) At this point, the carrier has the shape it needs to bind 2 potassium ions outside the cell
6) when the potassium ion binds, the phosphate group is released, (dephosphorylation) and the carrier protein is restored to its original shape
7) the change in conformation allows the carrier protein to pump 2 potassium ions inside the cell. The process is ready to begin again.

Question 10

Name the enzymes involved in post translational modification and their functions

Answer 10

Kinase: adds phosphates to an enzyme/protein

Phophotase: removes phosphates from a enzyme/protein

Question 11

Why may kinases and phosphatase be used then?

Answer 11

To deactivate or active proteins using post translational modification

Question 12

What can phosphorylation be when involved with proteins

Answer 12

A form of post translational modification

Question 13

What are uniport, symport, antiport

Answer 13

Transporter proteins

Question 14

Describe uniport

And is it passive or active

Answer 14

Transport molecules from one side of the membrane to the other along a concentration gradient.

Passive

Question 15

Describe symports

And give an example

Answer 15

Active transporter, where transporting one molecules results in the transportation of another in the same direction.

E.g glucose symport

Question 16

Describe antiport

And give an example

Answer 16

Active transporter, of two molecules being transported in opposite direction

E.g Na/K pump