Membranes

Question 1

What type of molecules are able to easily pass through the membrane?

Answer 1

Lipid soluble

Question 2

High levels of what ion are present inside the cell membrnae?

Answer 2

Potassium

Question 3

Name the fluid that surrounds cells

Answer 3

Interstitial fluid

Question 4

What is diffusion?

Answer 4

Free and random movement of substances to fill the available space evenly

Question 5

What is osmosis?

Answer 5

Water moving through a membrane to even up concentrations until equilibrium is reached

Question 6

What is osmolarity?

Answer 6

The number of particles in a solution

Question 7

What is the osmotic pressure?

Answer 7

The pressure that must be applied to oppose osmosis

Question 8

What does tonicity compare?

Answer 8

A solution and a cell

Question 9

What is the role of channel proteins?

Answer 9

Create a selective tunnel that acts as a passage through the membrane - no saturation limit

Question 10

What is the role of carrier proteins?

Answer 10

Move specific molecules through the membrane in a series of conformational changes

Question 11

How is energy used in

1. primary active transport
2. secondary active transport

Answer 11

1. directly

2. indirectly

Question 12

At what voltage is resting potential?

Answer 12

-60mV

Question 13

What is an action potential?

Answer 13

Successive opening of voltage gated sodium channels

Question 14

What is depolarisation?

Answer 14

A positive shift in the cells resting potential

Question 15

What is hyperpolarisation?

Answer 15

A negative shift in a cells resting potential

Question 16

What is a patch clamp?

Answer 16

An isolated area where the potential difference of the membrane is measured

Question 17

Describe the structure of a voltage gated sodium ion channel

Answer 17

• 1x24 TransMembrane (TM) domains

- TM domains grouped into 4 “repeats” (SI to SIV) giving the appearance of 4 subunits.

Question 18

What is hyperkalemia?

Answer 18

• sodium ion channels open when they shouldn’t
• can’t be treated
• periodic paralysis

Question 19

What is neuromyotonia?

Answer 19

• disease of voltage gated potassium channels

- muscles stay contracted as the channels arent switched off

Question 20

Give 3 examples of when exocytosis occurs

Answer 20

• hormone release
• digestive enzymes
• ## neurotransmitter release

Question 21

Give examples of endocytosis

Answer 21

• Phagocytosis: Macrophages engulf invading microbes and aged blood cells
• Pinocytosis: “Cell drinking” droplets of ECF are taken up into cells

Question 22

What is transcyosis?

Answer 22

• Moving substances through cells

Used for moving substances (e.g. large proteins) from blood across capillary endothelium into interstitial fluid

Question 23

Which proteins in the liver allow facilitated transport of glucose into the cell?

Answer 23

GLUT2 proteins

Question 24

What happens in hepatocytes following a meal?

Answer 24

1. Binds to its specific receptor and up-regulates production of hexokinase
2. Increased rate of conversion of glucose to glucose – 6 – phosphate
3. Glucose is metabolised lowering its concentration in the cytosol of the hepatocyte

Question 25

What is hyperglycemia?

Answer 25

Increased glucose concentration in the blood