Chapter 3 - Cell Membrane Transport

Question 1

What is the Plasma Membrane? What are its 3 functions?

Answer 1

• Outer surface of cells
• Separates extracellular fluid from cell’s cytoplasm
• Selective Permeability: Controls movement of substances entering + leaving the cell
• Provide recognition + communication between cells

Question 2

Describe the Plasma Membrane’s structure. (2 points)

Answer 2

• Phospholipid bilayer (2 layer) = fluid mosaic model
• Proteins embedded/attached to surface of membrane

Question 3

What is a Phospholipid? (2 points)

Answer 3

• One end is hydrophilic = head
• One end is hydrophobic = tail

Question 4

What type of molecules can or cannot pass through the Phospholipid layer? Give an example.

Answer 4

Permeable to:
- Small uncharged molecules (O2)
- Very small polar molecules (H20 + C02)

Impermeable to:
- Large polar molecules (Glucose)
- Charged particles (H+)

Question 5

What is tonicity?

Answer 5

Refers to the concentration of solute in a solution.

Question 6

What are the 3 types of tonicities?

Answer 6

1. Hypotonic
2. Hypertonic
3. Istonic

Question 7

What is a Hypotonic solution? (3 points)

Answer 7

• Lower concentration of solute relative to the cell
• Water will rush in –> attempt to reach equilibrium
• Causing the cell to burst

Question 8

What is a Hypertonic solution? (3 points)

Answer 8

• Higher concentration of solute relative to the cell
• Water will rush out –> attempt to reach equilibrium
• Causing the cell to look shriveled

Question 9

What is an Isotonic solution? (2 points)

Answer 9

• Same concentration of solute as the insides of a cell
• Shape will remain the same

Question 10

What is the difference between Active and Passive Transport?

Answer 10

• Active: Transport that requires energy from the cell
• Passive: Transport that does not require energy from the cell

Question 11

List 3 Passive Transportations.

Answer 11

1. Simple Diffusion
2. Facilitated Diffusion
3. Osmosis

Question 12

What is Simple Diffusion?

Answer 12

Non-polar + Uncharged molecules move a region of high to low concentration.

Question 13

How do gases and lipids enter a cell?

Answer 13

By diffusion following a concentration gradient.

Question 14

What is Facilitated Diffusion?

Answer 14

• Movement of water-soluble molecules following down a concentration gradient through a carrier/channel protein.
• Involves charged + polar molecules

Question 15

How do ions and glucose enter a cell?

Answer 15

By facilitated diffusion following down a concentration gradient with the help of a carrier protein.

Question 16

What is Osmosis?

Answer 16

Diffusion of water following down a concentration gradient.

Question 17

List 5 Active Transportations.

Answer 17

1. Active Transport
2. Exocytosis
3. Endocytosis
4. Phagocytosis
5. Pinocytosis

Question 18

What is Active Transport? (2 points)

Answer 18

• Movement of substances against their concentration gradient (low to high) that requires energy ATP w/ the help of protein pumps/carriers.
• A protein carrier binds to the molecule + uses the energy from ATP to change its shape and moves the molecule across the membrane.

Question 19

What is Endocytosis?

Answer 19

• Part of the plasma membrane engulfs the substance to be ingested
• Seperates from the membrane –> enclosing the substances in a vesicle
• Moves into the cell

Question 20

What are the 2 types of Endocytosis?

Answer 20

1. Phagocytosis
2. Pinocytosis

Question 21

What is Phagocytosis? (2 points)

Answer 21

• Cell eating of larger particles that are enveloped (vesicle) by the cell membrane to form a food vacuole.
• Going into the cell

Question 22

What is Pinocytosis? (2 points)

Answer 22

• Absorption of extracellular fluids/solvents that are enveloped (vesicle) by the cell membrane.
• Going into the cell

Question 23

What is Exocytosis? (4 points)

Answer 23

1. Large molecules are enclosed in a vesicle
2. Travels to the plasma membrane where it fuses together
3. Vesicle spills the larger molecules outside the cell

• Leaving the cell

Question 24

How do bacteria and viruses leave/enter the cell?

Answer 24

Phagocytosis and Exocytosis