Topic 2: Cell Physiology 1 - The Cell Membrane

Question 1

What are the 3 structures found within the cell membrane?

Answer 1

1. Phospholipid bilayer
2. Membrane Proteins
3. Membrane carbohydrates

Question 2

What is the phospholipid bilayer?

Answer 2

• continuous layer around the cell

Question 3

What is the function of the phospholipid bilayer?

Answer 3

barrier to water soluble substances

Question 4

What is the phospholipid bilayer permeable to? (2)

Answer 4

• permeable to small molecules (CO2 and O2)
• lipid soluble molecules

Question 5

What are the 5 types of membrane proteins?

Answer 5

1. Transport proteins
2. Receptor proteins
3. enzymes
4. Joining proteins
5. Identifying proteins

Question 6

What are 2 types of transport proteins?

Answer 6

• channel
• carrier

Question 7

What do channel proteins form in the membrane?

Answer 7

• form pore in membrane

Question 8

What is the function of a channel protein?

Answer 8

• selectively permit channel-mediated facilitated diffusion of water and specific ions

Question 9

Channel proteins can either be ___ or non-___

Answer 9

gated, non-gated

Question 10

What is a gated channel protein?

Answer 10

• can open or close when signaled

Question 11

What is a non-gated channel protein? (2)

Answer 11

• leakage channels
• always open

Question 12

What is the function of carrier proteins?

Answer 12

• bind solute and carry it across membrane

Question 13

What do carrier proteins allow for?

Answer 13

• allow protein carrier-mediated facilitated transport OR active transport

Question 14

What is a good example of a carrier protein?

Answer 14

glucose transport
- depends on where in the body (depends on CG)

Question 15

What is the function of receptor proteins?

Answer 15

• can bind specific extracellular molecules (ligands)
  ex. hormones, neurotransmitters

Question 16

Glucose uptake is an example of a receptor protein. What occurs here? (4)

Answer 16

• by skeletal muscle cells or adipose tissue
  1. insulin binds to receptor on skeletal muscle or adipose tissue
  2. Triggers movement of more glucose transporters to cell membrane
  3. Increased glucose movement from blood into cells

Question 17

What is the function of enzymes?

Answer 17

• Control chemical reactions on outer or inner surface
  ex. acetylcholinesterase
  ex. Na/K - ATPase where all cells have this

Question 18

What is the function of joining proteins?

Answer 18

• anchor cell membrane to cytoskeleton or an adjacent cell

Question 19

What are 2 types of joining proteins?

Answer 19

• junctional proteins
• extracellular fibers (usually glycoproteins)

Question 20

What do junctional proteins between cells form? (3)

Answer 20

• desmosomes
• tight junctions
• gap junctions

Question 21

What is an example of an identifying protein?

Answer 21

• Major Histocompatibility Complex (MHC)

Question 22

Where are MHC proteins found?

Answer 22

• On surface of all cells except RBC

Question 23

What is the function of MHC proteins?

Answer 23

identify cell as “self” (part of the body)
- not foreign

Question 24

What are 2 membrane carbohydrates?

Answer 24

• glycoproteins and glycolipids
  note that it is attached to lipid on phospholipid bilayer

Question 25

What is the function of membrane carbohydrates? (2)

Answer 25

• differs for every cell type
• allows cell to recognize type
  ex. sperm recognizes egg