Fluid Mosaic Model

Question 1

Outline base of fluid mosaic model.

Answer 1

Cell membranes are made of phospholipid bilayers, consisting of 2 layers of phospholipid molecules.
Phospholipid molecule consists of a phosphate head and 2 lipid tails.
Lipid tails are hydrophobic, phosphate heads are hydrophilic.
When placed in solution phospholipid molecules arrange themselves into 2 layers, the hydrophobic tails facing away from the water and the hydrophilic heads facing outwards.

Question 2

Within the intracellular environment of cell membrane are:

Answer 2

Cholesterol
Transport proteins
Receptor proteins
Recognition proteins
Adhesion proteins

Question 3

Within the extracellular environment of cell membrane are:

Answer 3

Carbohydrate molecules
Proteins

Question 4

Function of Cholesterol

Answer 4

Allows for membrane flexibility, animal cells only.

Question 5

Function of Transport proteins

Answer 5

Passageways that allow specific substances to move through membrane.

Question 6

Function of Receptor proteins

Answer 6

different in different cells, cause cells to respond only to certain signals from substances such as the hormones that bind them thus giving them different functions.

Question 7

Function of Recognition/glycoproteins

Answer 7

a protein molecule with carbohydrate molecules attached, they identify the cell and are called antigens/marker molecules allowing the immune system to recognise between foreign particles and body cell particles, ensuring the immune only destroys ‘nonself’ particles.

Question 8

Function of adhesion proteins

Answer 8

link together cells, helping maintain the organisms 3D structure.

Question 9

Functions of Cell Membrane

Answer 9

Separate - separates content of cell (intracellular fluid) from external environment/extracellular fluid. Eukaryotic cells ONLY have membranes used to create organelles within the cell.

Regulate - cell membrane can determine what goes in and out of a cell thus regulating what is in the cell, it is semi permeable; molecules can pass through via active or passive transport.

Communicate - involved in cell recognition and communication, must be able to recognise each other, e.g. immune system, recognise pathogens and thus kill.
Involved are: Glycoproteins, glycolipids and integral proteins.

Question 10

Features of Prokaryotes, give examples

Answer 10

No nucleus or membrane bound organelles.
Ribosomes
Most have cell wall
DNA floats in cytoplasm
Pili or flagella
Small
Bacteria, archaea.

Question 11

Features of Eukaryotes, give examples

Answer 11

Nucleus and membrane bound organelles
DNA in nucleus
Large
Animals, plants, fungi, protists.