B2.1 Cells and cell structure

Animal cells have the following parts:

A nucleus - Controls the activities of the cell

Cytoplam - Most chemical reactions take place here

A cell membrane- Controls the passage of substances in and out of the cell

Mitochondria-Where most energy is release in respiration

Ribosome- Which are where protein synthesis occurs

Plant cells have the same but also:

A cell wall- Made of cellullose which strengthens the cell

Chloroplasts- Absorb light energy to make food 

A permanent vacuole- Filled with cell sap

Bacterial cells consist of:

Cytoplasm

Cell wall

The genes (chromasomes) not in a neucleus

A yeast cell is single-celled and consists of:

A nucleus

Cell membrane

Cell wall

Cytoplasm

Cells may be specialised to carry out a specififc function e.g. root hair cell

What is Diffusion?

 Spreading out of particles (of a gas, or any substance in a solution) resulting in a net movement from a region where they are of higher concerntration to a region wih lower concerntration.

Dissolved substances can move in or out of cells by diffusion. 

The greater the difference in concerntration, the faster rate of diffusion

Oxygen required for respiration passes through cell membranes by diffusion