The Cell Membrane

Question 1

What model is used to explain the cell membrane.

Answer 1

Fluid mosaic model.

Question 2

What are the three types of molecules found in the cell membrane.

Answer 2

Phospholipid molecules
proteins
carbohydrates

Question 3

What substances is the bi - layer of phospholipids impermeable to?

Answer 3

Amino acids
glucose
salts
nucleic acids

Question 4

What is the structure of a phospholipid molecule - head and tail.

Answer 4

The heat is hydrophilic
The tail is hydrophobic

Question 5

What are the two types of protein molecules that we find in the cell membrane

Answer 5

Channel integral proteins - Only allow specific ions through ( gap between )
Carrier proteins - carries substances from one side to another ( smaller )

Question 6

Where are the carbohydrate molecules found

Answer 6

The carbohydrate molecules are on the protein molecules at the top creating a glycoprotein hence containing glucose

Question 7

What are the functions of the cell membrane?

Answer 7

Protection - the cell membrane is a boundary outside of the cytoplasm keeping all the contents of the cell together.
Selectively/differentially permeable - certain substances that are required by the cell in or out.

Question 8

What does movement across the cell membrane mean?

Answer 8

Transport

Question 9

What are the two different types of transport and give an example of each?

Answer 9

Passive transport - osmosis/diffusion
Active transport - enzyme secretion/a macrophage ingesting bacteria

Question 10

What defines active transport?

Answer 10

The fact that energy is required for the process to take place.
ATP energy is supplied by the mitochondria.

Question 11

What defines passive transport?

Answer 11

The fact that no outside energy is required.
The kinetic energy of the moving molecules supplies sufficient energy.

Question 12

What is diffusion?

Answer 12

The random motion of particles of a molecule from a region of high concentration to a region of low concentration until dynamic equilibrium is reached( the particles are evenly spread throughout the region)

Question 13

What is osmosis?

Answer 13

The diffusion of water molecules from a region of high water potential (more pure water ) to region of lower water potential (less pure water ) - through a selectively permeable membrane.

Question 14

What is a water potential?

Answer 14

Concentration of H20 molecules and Ek.
High water potential - high concentration and high Ek
Low water potential - low concentration and low Ek

Question 15

Describe hypertonic , hypotonic and isotonic.

Answer 15

Hypertonic - equal concentration between solutes and water molecules
Hypertonic - higher concentration of solutes 
Hypotonic - lower concentration of solutes

Question 16

What is Active transport?

Answer 16

The transport of substances against a diffusion gradient - from low concentration to a high concentration.
Transportation of large molecules through cell membrane to cell.