1.3

Question 1

What is the plasma membrane?

Answer 1

A fluid mosaic bilayer of phospholipids and proteins

Question 2

How do hydrophilic head groups align?

Answer 2

To the extracellular space or cytoplasm

Question 3

Where to the hydrophobic tails point?

Answer 3

inwards

Question 4

What are the two types of proteins in the membrane?

Answer 4

Integral and Peripheral

Question 5

In integral proteins, what do the hydrophobic R groups allow?

Answer 5

Strong hydrophobic interactions holding membrane proteins within the phospholipid bilayer

Question 6

Some integral proteins are transmembrane, what does this mean they do?

Answer 6

Span the width of the membrane

Question 7

Are peripheral proteins embedded in the bilayer?

Answer 7

no

Question 8

Are integral proteins embedded in the bilayer?

Answer 8

Yes

Question 9

What do the hydrophilic R groups of the surface of peripheral proteins do?

Answer 9

They are bound to the surface of membranes mainly by ionic and hydrogen bond interactions and they can interact with the surfaces of integral proteins

Question 10

The phospholipid bilayer is a barrier to……

Answer 10

ions and uncharged polar molecules

Question 11

What is facilitated diffusion?

Answer 11

The passive transport of substances across the membrane through specific transmembrane proteins.

Question 12

What are the channels water can pass through?

Answer 12

Aquaporins

Question 13

What are the two types of membrane channel?

Answer 13

Ligand-gated and voltage-gated

Question 14

What are ligand-gated channels controlled by?

Answer 14

The binding of signal molecules (e.g. neurotransmitter)

Question 15

What are voltage-gated channels controlled by?

Answer 15

Changes in ion concentration

Question 16

What are the jobs of membrane channels?

Answer 16

Change conformation to allow or prevent diffusion.

Question 17

What do Transporter Proteins do?

Answer 17

Bind to a specific substance to be transported and undergo a conformational change to transport a solute across the membrane

Question 18

Do transporter proteins require energy?

Answer 18

Some do

Question 19

ATPases…..

Answer 19

hydrolyse ATP

Question 20

How is the membrane potential created?

Answer 20

When there is a difference in electrical charge on two sides of the membrane.

Question 21

What is the Sodium-Potassium pump and what does it do?

Answer 21

It’s an ion pump that uses energy from the hydrolysis of ATP to establish and maintain ion gradients

Question 22

Is Na+ pumped in or out?

Answer 22

Out

Question 23

How many NA+ are pumped out?

Answer 23

3

Question 24

Is K+ pumped in or out of the cell?

Answer 24

In

Question 25

How many K+ are pumped in?

Answer 25

2

Question 26

What is a symporter?

Answer 26

An integral membrane protein involved in the transport of different molecules.

Question 27

Na+ ions enter the cell ____ their concentration gradient

Answer 27

down

Question 28

the simultaneous transport of glucose into the cell is ____ the concentration gradient

Answer 28

against

Question 29

What are the functional steps of the sodium-potassium pump?

Answer 29

1. Transporter protein has high affinity for sodium ions inside the cell therefore binding occurs.
2. Phosphorylation by ATP causes the conformation of the protein to change
3. Affinity for ions changes resulting in Na+ being released out of the cell.
4. K+ ions from the outside of the cell bind to the pump
5. Dephosphorylation occurs causing conformation of protein to change
6. K+ ions are taken into the cell and affinity returns to the start.