Cell transport mechanisms

Question 1

What are the 2 types of transport?

Answer 1

1. Passive transport
2. Active transport

Question 2

What are two types of passive transport?

Answer 2

1. Simple diffusion
2. Facilitated diffusion

Question 3

What is passive transport?

Answer 3

The movement of molecules across the cell membrane down a concentration gradient without the need for energy.

Question 4

What is active transport?

Answer 4

The movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, through the use of energy.

Question 5

What is simple diffusion?

Answer 5

It is a natural movement that does not require a transport protein.

Question 6

What is facilitated diffusion?

Answer 6

The movement of molecules that utilise a transport protein.

Question 7

What are pores with regard to cell transport mechanisms?

Answer 7

• Pores are always open and can freely permit the movement of substances through diffusion with the concentration gradient.
• Pores are more selective to the types of molecules they allow to pass through.

Question 8

How can gates be categorised?

Answer 8

• voltage-gated
• ligand-gated

Question 9

What are voltage gates with regard to cell transport mechanisms?

Answer 9

They respond to the actual charge of an ion and will respond to it by changing its shape allowing the ion to pass through to the other side of the cell membrane.

Question 10

What are ligand gates with regard to cell transport mechanisms?

Answer 10

They respond to a binding, causing it to open the gate and let the substance move to both the two sides of the cell membrane.

Question 11

Define ‘conformational change’.

Answer 11

A temporary adjustment to how that protein appears to allow the passage of a molecule.

Question 12

What are ion pumps with regard to cell transport mechanisms?

Answer 12

• They have the capacity to move more than one ion across the cell membrane.
• Vital in maintaining the concentration of substances in the intracellular and extracellular spaces.

Question 13

What is an example of an ion pump?

Answer 13

Sodium Potassium pump

Question 14

What is the sodium-potassium pump?

Answer 14

• An integral membrane protein that spans the width of the phospholipid bilayer.
• Uses ATP to move ions via active transport.

Question 15

Outline the 4 steps on how sodium-potassium pumps function.

Answer 15

1. Protein binds 3 sodium ions and a molecule of ATP.
2. Splitting of ATP provides energy to change the shape of the channel which releases sodium ions.
3. Once released the new shape of the pump allows 2 potassium ions to bind.
4. Potassium is released into the cell allowing the pump to revert back to its original shape.

Question 16

What is ATPase?

Answer 16

An enzyme is involved in splitting ATP to ADP and utilising energy.

Question 17

What are the 3 effects of the sodium-potassium ion pump?

Answer 17

1. Make sodium concentration high in the extracellular space and low in the intracellular space.
2. Make potassium concentration high in the intracellular space and low in the extracellular space.
3. Gives the intracellular space a negative charge.