1.3

Question 1

What acts as a barrier to most charged polar molecules and ions

Answer 1

The phospholipid bilayer

Question 2

Name the chemical components of a cell membrane

Answer 2

Phospholipids, transmembrane protein and peripheral proteins

Question 3

Describe the head region of a phospholipid molecule

Answer 3

Charged therefore is hydrophilic (attracted to water)

Question 4

Describe the tail region of a phospholipid molecule

Answer 4

Uncharge and non-polar therefore hydrophobic (Doesn’t like water)

Question 5

Describe intergral proteins

Answer 5

Regions of hydrophobic R groups allow strong hydrophobic interactions that hold integral membrane proteins within the phospholipid bilayer
Some integral membrane proteins are transmembrane proteins

Question 6

Describe facilitated diffusion

Answer 6

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

Question 7

Describe peripheral proteins

Answer 7

Have hydrophilic r groups on their surface and are bound ti the surface of membrane by ionic and hydrogen bonds

Question 8

What type of molecules can pass directly through the membrane ?

Answer 8

Non-polar molecules

Question 9

What are the two types of channels?

Answer 9

Gated and undated

Question 10

Give an example of an undated channel

Answer 10

Aquaporin

Question 11

Describe aquaporin and its functions

Answer 11

Ungated channel that allows water to pass thought the membrane

Question 12

What are the two types of gated channels?

Answer 12

Ligand and Voltage Gated

Question 13

What is Ligand-gated channels

Answer 13

The binding of signal molecules

Question 14

What is voltage-gated channels

Answer 14

Changes in the ion concentartion

Question 15

Describe how transporter proteins work

Answer 15

Change conformation to transport molecules across the membrane

Question 16

Name 2 small molecules that can diffuse directly across the phospholipid bilayer

Answer 16

Oxygen and Carbon dioxide

Question 17

What is the function of channel proteins

Answer 17

allow passive transport down the concentration gradients

Question 18

Active transport

Answer 18

Active transport uses pump proteins that transfer substances across the membrane against their concentration gradien

Question 19

Membrane potential

Answer 19

Created when there is a difference in electronically charge on the two side of the membrane

Question 20

Sodium-potassium pump

Answer 20

This transports ions against a steep concentration gradient using energy directly from ATP hydrolysis
It actively transports 3 Na ions out of the cell and 2 K ions into the cell per ATP hydrolysed

Question 21

Steps of NaKATPase pump

Answer 21

1. Pump has a high affinity for Na ions inside the cell
2. Binding occurs and the pump is phosphorylated by ATP
3. Confirmation of the protein changes and the affinity for Na ions decrease. Therefore releasing Na outside the cell
4. k ions bind to the outside of the cell
5. Dephosphorylation occurs and the confirmation of the protein changes
6. K ions are released into the cell due ti a lowered affinity

Question 22

Glucose symport

Answer 22

Small intestine epithelial the Na gradient drives the active transport of glucose whereas in intestinal epithelial cells the NaKATPase pump generates a Na ion gradient across the plasma membrane

Na ions enter the cell down their concentration gradient (passive); this provides energy for simultaneous transport of glucose pumps glucose into the cell against its concentration gradient