Unit 1: Cell Membrane

Question 1

What is the function of the Cell Membrane

Answer 1

• Separates the inside of the cell from its environment
• Controls what enters the cells
• Involved in the excretion of cellular wastes
• Involved in cell recognition and immunity

Question 2

what are the four biomolecules in the cell membrane

Answer 2

1. carbohydrates
2. lipids
3. proteins
4. nucleic acids

Question 3

what is the cell membrane made out of?

Answer 3

fluid mosaic phospholipid bilayer

Question 4

structure of the phospholipid?

Answer 4

they have hydrophilic heads and hydrophobic tails

Question 5

what role does cholesterol play in the membrane?

Answer 5

cholesterol is a lipid in the membrane, which helps stabilise and strengthen the membrane, and maintain suitable fluidity

Question 6

Describe the 3 forms and processes of Passive transport (doesn’t require energy)

Answer 6

1. Diffusion - water molecules travelling across the semi-permeable membrane, with the concentration gradient
2. Facilitated Diffusion - transport proteins (carrier and channel proteins) assisting larger or charged molecules across the membrane
3. Osmosis - special type of diffusion over a differentially permeable membrane, against the concentration gradient

Question 7

Describe 3 forms and processes of Active transport (does require energy)

Answer 7

1. endocytosis - cell membrane folds around large food particle, forms a vacuole (sack) and stores the water
2. exocytosis - large molecules are transported out to the external environment (reverse endocytosis)
3. Ion pump - transport proteins that require energy to do work

Question 8

what factors affect direction of movement?

Question 10

how is diffusion impacted by surface area to volume ration?

Question 10

is a larger surface:volume