Biology

Most animal cells contain: A nucleus, cytoplasm, cell membrane, mitochondria and ribosomes.

Plants contain all the structures seen in animal cells as well as: A cell wall and in many cases chloroplasts and a permanent vacuole filled with sap.

Biological catalysts, called enzymes control the reactions inside these cells. the enzymes involved in different chemical reactions are usually found in different parts of the cell. The enzymes used for;

• respiration are found in the mitochondria
• photosynthesis are found in the chloroplasts
• protein synthesis are found in the ribosomes

The smallest livivng organisms are single cells, which are able to carry out all the functions of normal life. Most organisms are bigger and made up of lots of cells, which some of them become specialised in order to carry out particular jobs.When a call becomes specialised it's shape adapts to suit a particular job it has.Good examples of this include:

• Sperm cells
• eggs
• red blood cells
• nerve cells
• fat cells
• cone cells 
• root hair cells