2.3 Transport Across Cell Membranes

Question 1

What model do all membranes have

Answer 1

Fluid-mosaic

Question 2

What are the major components to the cell membrane

Answer 2

• Phospholipid Bilayer
• Channel Protein
• Carrier Protein
• Glycoprotein
• Glycolipid
• Cholesterol

Question 3

Name the component of the cell membrane

Answer 3

Phospholipid Bilayer

Question 4

Name the component of the cell membrane

Answer 4

Channel Protein

Question 5

Name the component of the cell membrane

Answer 5

Glycoprotein

Question 6

Name the component of the cell membrane

Answer 6

Carrier Protein

Question 7

Name the component of the cell membrane

Answer 7

Glycolipid

Question 8

Name the component of the cell membrane

Answer 8

Cholesterol

Question 9

Describe the arrangement of phospholipid molecules in the phospholipid bilayer

Answer 9

• Two layers of phospholipids
  Hydrophilic heads face outside
• Hydrophobic tails face inside

Question 10

Describe and explain the advantages of the phospholipid bilayer in the cell membrane

Answer 10

• Selectively-permeable barrier
• Only non-polar molecules are able to pass through via simple diffusion
• Bilayer is fluid
• Can bend to take up different shapes, forming vesicles

Question 11

Describe and explain the advantages of channel proteins in the cell membrane

Answer 11

• Protein through bilayers
• Allows water soluble substances through via faccilitated diffusion

Question 12

Describe and explain the advantages of carrier proteins in the cell membrane

Answer 12

• Protein through bilayer
• Allows substances to move through via faccilitated diffusion and active transport

Question 13

Describe and explain the advantages of glycoproteins in the cell membrane

Answer 13

• Protein with short carbohydrate chain
• Cell recognition and signalling
• Cell attachment

Question 14

Describe and explain the advantages of glycolipids in the cell membrane

Answer 14

• Phospholipid with short carbohydrate chain
• Cell recognition and signalling
• Cell attachment

Question 15

Describe and explain the advantages of cholesterol in the cell membrane

Answer 15

Regulates membrane fluidity

Question 16

Simple diffusion: Movement of molecules

Answer 16

• Along concentration gradient
• From higher concentration to lower concentration

Question 17

Simple diffusion: Active or passive

Answer 17

• Passive
• No ATP hydrolysed

Question 18

Simple diffusion: Movement through what

Answer 18

Diffuse through phospholipid bilayer

Question 19

Simple diffusion: Type of molecule

Answer 19

Non-polar

Question 20

Faccilitated diffusion: Movement of molecules

Answer 20

• Along concentration gradient
• From higher concentration to lower concentration

Question 21

Faccilitated diffusion: Active or passive

Answer 21

• Passive
• No ATP hydrolysed

Question 22

Faccilitated diffusion: Movement through what

Answer 22

Channel and carrier proteins

Question 23

Faccilitated diffusion: Type of molecule

Answer 23

Polar / Charged

Question 24

Osmosis: Movement of molecules

Answer 24

• Movement of water along a water potential gradient
• From an area of high water potential
• To an area of low water potential

Question 25

Osmosis: Movement of molecules regarding solute concentration

Answer 25

Low to high solute concentration

Question 26

Osmosis: Passive or active

Answer 26

* Passive * No ATP hydrolysed

Question 27

Osmosis: Movement through what

Answer 27

Water channel proteins (aquaporins)

Question 28

Water IN by osmosis : Cell apperance

Answer 28

Turgid

Question 29

Water IN by osmosis : Cytoplasm

Answer 29

Hasn't shrunk from cell wall

Question 30

Water IN by osmosis : Cell in what solution

Answer 30

Hypotonic

Question 31

Water IN by osmosis : Water potential of cell and solution

Answer 31

Solution has higher water potential than cell

Question 32

Water IN by osmosis : Net movement of water

Answer 32

Into the cell by osmosis

Question 33

Water OUT by osmosis : Cell appearance

Answer 33

Plasmolysed

Question 34

Water OUT by osmosis : Cytoplasm

Answer 34

Shrunk from cell wall

Question 35

Water OUT by osmosis : Cell in what solution

Answer 35

Hypertonic

Question 36

Water OUT by osmosis : Water potential of cell and solution

Answer 36

Solution has a lower water potential than the cell

Question 37

Water OUT by osmosis : Net movement of water

Answer 37

Out of the cell, by osmosis

Question 38

Water potential of pure water

Answer 38

0kPa

Question 39

Water potential of a solution more concentrated than pure water

Answer 39

Less than 0kPa

Question 40

Relationship between water potential and solute concentration

Answer 40

More concentrated solute = lower water potential

Question 41

Active Transport: Movement of molecules

Answer 41

* **Against concentration gradient** * From lower concentration to higher concentration

Question 42

Active Transport: Active or passive

Answer 42

* Active * Requires ATP hydrolysis

Question 43

Active Transport: Movement through what (+description)

Answer 43

* Carrier protein * Protein **changes shape,** as substrate binds

Question 44

What occurs when a substrate binds to a carrier protein

Answer 44

Protein changes shape

Question 45

Describe exocytosis

Answer 45

**Fusion of a vesicle** with the cell-surface membrane

Question 46

Describe endocytosis

Answer 46

**Engulfment** of molecules by cell-surface membrane to **form vesicles**

Question 47

State the ways in which cells adapt to increase the rate of transport across a membrane

Answer 47

* Increased number of channel and carrier proteins * Folded membrane * Increased number of mitochondria

Question 48

Describe how increasing the number of channel/carrier proteins increases the rate of transport across a membrane

Answer 48

More faccilitated diffusion / active transport

Question 49

Describe how a folded membrane increases the rate of transport across a membrane

Answer 49

Increases surface area

Question 50

Describe how an increased number of mitochondria increases the rate of transport across a membrane

Answer 50

Supply more ATP for active transport