Cell Membranes

Question 1

What is a glycoprotein

Answer 1

Protein with carbohydrate attached

Question 2

What is a glycolipid

Answer 2

Lipid with carbohydrate attached

Question 3

Properties of cholesterol

Answer 3

Maintains shape of animal cells

Hydrophobic regions, so causes a barrier against polar substances

Question 4

What does cholesterol do to the lipid bilayer

Answer 4

Makes it more stable

Question 5

How does cholesterol make the lipid bilayer more stable

Answer 5

Cholesterol binds to the hydrophobic tails of the phospholipids causing them to pack together more closely. This means they are unable to move as much and become more rigid

Question 6

What happens to the cell membrane below 0 degrees Celsius

Answer 6

Phospholipids don’t have much energy so cannot move, making them rigid and packed close together
Channel proteins and carrier proteins denature increasing the permeability of the membrane
Ice crystals form and pierce the membrane making it highly permeable when it thaws

Question 7

What happens to a cell membrane between 0 and 45 degrees Celsius

Answer 7

Phospholipids can move around
Partially permeable membrane
As temp increases so does movement of phospholipids as they gain energy, this increases permeability of membrane

Question 8

What happens to the membrane above 45 degrees Celsius

Answer 8

Phospholipids bilayer breaks down
Membrane becomes more permeable
Proteins denature increasing permeability

Question 9

How does facilitated diffusion via a carrier protein work

Answer 9

A large molecule attaches to a carrier proteins in the membrane
The protein changes shape
The released the molecule in the opposite side of the membrane

Question 10

How do channel proteins work

Answer 10

Form pores in the membrane for charged particles to diffuse through

Question 11

Water potential value of pure water

Answer 11

0

Question 12

What is water potential

Answer 12

Likelihood of water molecules to diffuse out of or into solution

Question 13

What is the water potential of any solution always negative

Answer 13

Adding solutes to pure water lowers the water potential

Question 14

More solutes in solution means

Answer 14

Lower water potential

Question 15

Isotonic means

Answer 15

Two solutions have the same water potential

Question 16

Describe the movement of water when there’s a higher water potential outside of the cell than inside the cell

Answer 16

Water molecules move by osmosis down its concentration gradient from the solution into the cell as it has a lower water potential. The cell will swell

Question 17

Solutions with a higher water potential than that of a cell are

Answer 17

Hypotonic

Question 18

Solutions with a lower water potential than that of a cell are

Answer 18

Hypertonic

Question 19

Describe the movement of water molecules when a cell is placed in solution with a lower water potential

Answer 19

Water molecules move out of the cell into volition by osmosis down their concentration gradient. Cell will shrink

Question 20

Where does the energy needed for active transport come from

Answer 20

The hydrolysis of ATP to ADP + Pi

Question 21

How many molecules bind to a co transporter

Answer 21

2

Question 22

Describe the absorption of glucose

Answer 22

Sodium ions actively transported out of the epithelial cells of the ileum into the blood via sodium potassium pumps
High conc of sodium ions in blood then cells
Sodium ions diffuse from the blood into the epithelial cells down their conc gradient via sodium glucose co transporter protein
Co transporter moves glucose too
Higher conc of glucose in cell than blood
Glucose undergoes facilitated diffusion down channel protein from cell to blood down its conc gradient