Specialised Cells

All cells are designed to do a particular job in an organism. This is called cell specialism. Examples of 5 specialised cells are shown below:

1) The sperm cell - designed to fertilise eggs

• A sperm cell is very small and has a little tail which provides movement so it can swim and find an egg to fertilise
• Its head contains enzymes (in the vacuole) which allow it to digest its way through an egg membrane so the two nuclei can join
• It contains half the number of chromosomes in the nucleus - these carry genetic information from the father, which will be passed on to the offspring

2) The ovum (egg) cell - designed to be fertilised

• An ovum is large and bulky because no active movement is needed - it just sits and waits for the sperm to find it
• It contains yolk (in the cytoplasm) which provides a large food store needed for the developing young organism once it's fertilised
• It contains half the number of chromosomes, which carry genetic information from the mother - this will be passed on to the offspring

3) The palisade cell - designed for photosynthesis

• A palisade cell is tall with a large surface area
• It's found on the top side of a leaf - ideal for good absorption of carbon dioxide and light - both are needed for photosynthesis
• They're packed with chloroplasts, which contain the green pigment chlorophyll, which is needed for photosynthesis

4) The cilia cell - designed to stop lung damage

• Cilia cells line all the air passages in your lungs
• They have tiny hairs, which filter the air as it blows through
• The hairs sweep mucus (snot) with trapped dust and bacteria up to the back of the throat where it is swallowed

5) The root hair cell - designed for absorbing

• The long hair cell increases the surface area of the root, which helps absorption of water and minerals
• It has a really thin cell wall, which makes it easier for minerals to pass across into the root itself