2.1 Cell Theory

5 Main concepts of cell theory

1. Cells are the structural/functional unit of all living things 2. All existing cells come from pre-existing cells 3.Cells use and require energy 4.Contains DNA 5. Can be unicellular/multicellular.

MRS C GREN Acronym

Movement, respiration, sensitivity (response to environmental changes), control, growth, reproduction, excretion and nutrition.

Cell membrane purpose

Separates the cell from its surroundings and controls the exchange of materials (nutrients and waste), between the cell and the environment.

Cell Membrane Structure

Made up of a phospholipid bilayer. Hydrophillic head interacts with water molecules on both sides of the membrane. Hydrophobic tail propel water across the membrane.

3 functions of the cell membrane

1. Separates cell contents from external environment 2. Regulates the passage of substances in/out the cell (like nutrients and waste) 3. Attaches to the cytoskeleton (gives cell shape and structure)

Fluid mosaic model - Fluid

'Islands of protein floating in a sea of lipid'. Fluid nature means its a dynamic structure, rather than static. Proteins move constantly in the membrane.

Fluid mosaic model - Mosaic

Mosaic, is the idea that the structure is made up of many components.