Topic 2 B

Question 1

What did the fluid mosaic model suggest about membranes?

Answer 1

The phospholipids are constantly moving, the way molecules are arranged

Question 2

What do channel and carrier proteins do in the membrane?

Answer 2

Allow large molecules and ions to pass through the membrane

Question 3

What do receptor proteins do in the membrane?

Answer 3

Detect chemical signals from other cells, which signals the cell to respond

Question 4

What are glycoproteins?

Answer 4

Proteins with a carbohydrate attached

Question 5

What are glycolipids?

Answer 5

Lipids with a carbohydrate attached

Question 6

What makes up the bilayer of the membrane?

Answer 6

Phospholipids

Question 7

What are the head and tails of the phospholipids considered as?

Answer 7

Hydrophobic tails, hydrophilic heads

Question 8

What does the phospholipid bilayer of the membrane prevent from entering the cell?

Answer 8

Water soluble substances

Question 9

What does cholesterol do in the membrane?

Answer 9

It fits between the phospholipids binding to the tails causing them to pack closely together, giving the membrane stability.

Question 10

How do temperatures below 0c affect the membrane?

Answer 10

Don’t have a lot of energy so cant move, channel and carrier proteins denature increasing the permeability. Ice crystals may form and pierce the membrane, making it highly permeable when it thaws

Question 11

How does temperatures between 0 and 45c affect the membrane?

Answer 11

Phospholipids can move around, partially permeable, permeability increases as temp does as the phospholipids have more energy

Question 12

How does temperatures above 45c affect the membrane?

Answer 12

Start to break down, becoming more permeable, water expands putting pressure, channel and carrier proteins denature which increases the permeability

Question 13

What is diffusion?

Answer 13

The movement of water particles from and area of higher concentration to an area of lower concentration, down concentration

Question 14

what are factors affecting diffusion?

Answer 14

The conc gradient, thickness of exchange surface, surface area

Question 15

What is facilitated diffusion?

Answer 15

Moving particles down a concentration, from higher con to lower conc with the help of proteins

Question 16

What are the two proteins involved in facilitated diffusion?

Answer 16

Carrier and channel proteins

Question 17

How do carrier proteins help facilitated diffusion?

Answer 17

Move large molecules across the membrane. It attaches to the carrier protein cause it to change shape, the molecule is released on the other side

Question 18

How do channel proteins help facilitated diffusion?

Answer 18

move charged particles across the membrane

Question 19

What factors affect facilitated diffusion?

Answer 19

Concentration gradient, number of channel and carrier proteins

Question 20

What is osmosis?

Answer 20

Diffusion of water molecules across a partially permeable membrane, from a higher water potential to a lower water potential

Question 21

What does it mean when cells are isotonic?

Answer 21

They have the same water potential

Question 22

What is it called when a solution has a higher water potential then the cell?

Answer 22

Hypotonic, water moves into cell

Question 23

What is it called when the solution has a lower water potential then the cell?

Answer 23

Hypertonic, water movies out of the cell

Question 24

What factors affect osmosis?

Answer 24

Water potential, thickness of exchange surface, surface area

Question 25

What is active transport?

Answer 25

Moving molecules and ions using energy against the conc gradient

Question 26

What proteins are involved in active transport?

Answer 26

Carrier and co transporters

Question 27

How are co transporters used in active transport?

Answer 27

Two molecules bind at the same time, the conc gradient of one molecule is sued to move the other against its conc gradient

Question 28

How is glucose co transported?

Answer 28

Sodium ions are actively transported out from the epithelial cells in the ileum into the blood by the sodium potassium pump. This creates a conc gradient, higher in lumen then cell Na+ ions diffuse from lumen into epithelial cells down conc gradient via sodium potassium co transport protein. Glucose is carried in as well increasing the conc in the cell Glucose then diffuses out of the cell into the blood down the conc gradient via facilitated diffusion

Question 29

What factors affect active transport?

Answer 29

Rate of respiration, the number of carrier and protein cells present, speed of carrier proteins