IB Biology: Level 6 - Structure of the Cell Membrane 1.3

Question 1

Essential idea

Answer 1

The structure of biological membranes makes them fluid and dynamic

Question 2

Nature of science

Answer 2

Using models to represent the real world.Falsifying theories with one theory being superseded by another.

Question 3

Extracellular space

Answer 3

Space outside of the cell the cell

Question 4

Phospholipid molecules

Answer 4

Major component of the cell.

Question 5

Amphiphilic

Answer 5

describing a chemical compound possessing both hydrophilic (water-loving, polar) and hypophobic (water-fearing)

Question 6

Phospholipid structure

Answer 6

Phosphate head (polar/ hydrophilic)GlycerolLipophilic |fatty acid| tails (non-polar/ hydrophobic)

Question 7

Gorter - Grendel Model

Answer 7

States that cell membrane is made of a lipid bilayer

Question 8

Davson - Danielli Model

Answer 8

• A protein-lipid sandwich-Lipid bilayer composed of phospholipids (head and tail)- Protein coat outer surface- Proteins do not permeate the lipid bilayer

Question 9

Davson - Danielli Model’s evidence

Answer 9

Electron micrographs membranes appeared as two dark parallel lines with a lighter coloured region in betweenProteins appear dark and phospholipids appear light

Question 10

Falsification of Davson-Danielli model

Answer 10

• Fracture occurs along lines of weakness, including centre of membranes- Fracture reveals rough surface inside phospholipids bilayer- The globular structures are trans-membrane proteins