Membrane transport

Question 1

Questions

Answer 1

Answers

Question 2

What is the function of the plasma membrane?

Answer 2

Forms a barrier between the cytoplasm and the environment

Question 3

What is the plasma membrane made up of?

Answer 3

Phospholipids.

Question 4

How do the hydrophobic tails and hydrophilic heads of phospholipids arrange themselves in the bilayer?

Answer 4

Hydrophobic fatty acid tails face inwards

Question 5

What is the function of the phospholipid bilayer?

Answer 5

Forms a barrier between water-soluble molecules and maintains different environments on each side of the membrane.

Question 6

Why is the cell membrane described as fluid?

Answer 6

Molecules in the membrane can move freely.

Question 7

What is the role of cholesterol in the cell membrane?

Answer 7

Cholesterol fits between fatty acid tails

Question 8

What is the role of channel proteins?

Answer 8

Allow transport across the membrane by facilitated diffusion (intrinsic proteins).

Question 9

What is the role of carrier proteins?

Answer 9

Allow transport across the membrane by moving charged particles from one side of the membrane to the other (intrinsic proteins).

Question 10

What is the role of glycoproteins?

Answer 10

Proteins with attached carbohydrate parts involved in cell recognition

Question 11

What is diffusion?

Answer 11

The net movement of molecules or ions from an area of high concentration to low concentration through a partially permeable membrane until dynamic equilibrium is reached.

Question 12

Why does diffusion occur?

Answer 12

Particles have kinetic energy

Question 13

What does diffusion result in?

Answer 13

Dynamic equilibrium

Question 14

What factors affect the rate of diffusion?

Answer 14

Concentration gradient

Question 15

What is Fick’s Law of Diffusion?

Answer 15

Diffusion ∝ (surface area × difference in concentration) / length of diffusion path.

Question 16

What is facilitated diffusion?

Answer 16

The movement of water-soluble

Question 17

How do channel proteins assist in facilitated diffusion?

Answer 17

They allow specific water-soluble ions and molecules to pass through; channels are only open for specific molecules.

Question 18

How do carrier proteins assist in facilitated diffusion?

Answer 18

Carrier proteins bind to specific molecules

Question 19

What is osmosis?

Answer 19

The movement of water from a region of high water potential to low water potential through a partially permeable membrane until dynamic equilibrium is reached.

Question 20

What happens to cells in a hypertonic solution?

Answer 20

In plant cells: water moves out

Question 21

What happens to cells in a hypotonic solution?

Answer 21

In plant cells: water moves in

Question 22

What happens to cells in an isotonic solution?

Answer 22

Dynamic equilibrium is reached; no net water movement occurs.

Question 23

What is active transport?

Answer 23

The movement of molecules or ions against a concentration gradient using energy in the form of ATP and requiring carrier proteins.

Question 24

How does active transport occur?

Answer 24

A molecule binds to a carrier protein. ATP binds

Question 25

What are the types of active transport?

Answer 25

Uniport (single molecule)

Question 26

What is endocytosis?

Answer 26

The process where materials are surrounded by the membrane and taken into the cell.

Question 27

What is exocytosis?

Answer 27

The process where a membrane-bound vesicle empties its contents outside the cell.

Question 28

What is phagocytosis?

Answer 28

“Cell eating

Question 29

What is pinocytosis?

Answer 29

“Cell drinking

Question 30

What is the difference between diffusion and active transport?

Answer 30

Diffusion moves molecules down the concentration gradient and does not require energy. Active transport moves molecules up the concentration gradient and requires ATP and carrier proteins.