# Specialised Cells

Source: https://projectgcse.co.uk/biology/life_processes_cell_activity/specialised_cells

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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