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Cell divison and cancer

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Cell structure and transport

Humans are multi cellular organisms. That means they are made up of billions of individual cells. These cells are not all the same. There are many different cell types that are specialised to perform the range of functions needed in a complex organism.

Different types of cells

As new cells grow and replicate, they become specialised to do particular jobs. Nerve cells that carry electrical signals, muscle cells which generate force and pancreas cells making insulin are just a few examples. Amazingly, all of these cells have grown from just one single fertilised egg cell.

Cells like these line the windpipe or trachea. The cell membrane is folded into tiny hairs which can move and push dust particles out of the lungs.

Many types of cancer, including those of the stomach, lung, skin and bowel, start off in epithelial cells. These cells line your organs and tissues and are exposed to environmental influences which, over time, can cause cancer to arise. For example smoking and lung cancer, ultraviolet radiation and skin cancer.

Sperm cell

The sperm cell has a tail so it can 'swim' to fertilise an egg cell. It has lots of mitochondria to generate the energy it needs.

Nerve cell

Nerve cells have branches coming out from the main part of the cell. These can carry nerve signals and connect to other nerve cells, receptors or muscles.

How molecules move in and out of cells

Substances can cross the cell membrane by diffusionosmosis and active transport. Use the animation to see how each of them works.