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Year 7 & 8 TOC

Specialised cells

Cell Division

Recognising that cells reproduce via cell division & describing mitosis as cell division for growth and repair

Something that all organisms have in common, is their need to replicate or reproduce. Living organisms are constantly making new cells. They replicate to grow, reproduce or replace old dead cells. This process is called cell division. 


Simple unicellular organisms, like bacteria, will reproduce through a process called binary fission. This is where a cell divides and creates 2 identical new cells.

  1. First the DNA replicates and the cell grows, doubling its size.
  2. Then the duplicate strands of DNA move to opposite sides of the cell.
  3. The cell wall “pinches” off in the middle forming two separate cells.

Watch the time lapse below of a small colony of bacteria replicating. 



Multicellular organisms have cells which are more complex. When our cells divide its through a process called Mitosis. Your cells will undergo mitosis each time you cut yourself or damage your body, your cells will replicate to fix you. In fact, you started life off as just a single cell and now you are around 1 billion cells!

During Mitosis, a cell will make an identical copy of itself. Replicating all the organelles and internal structures. The cell which divides is called the mother cell, while the two new cells are called daughter cells. At the beginning the nucleus divides into 2, then the cytoplasm and by the end we have 2 identical cells.

Watch the video below, of mitosis in action.  


Meiosis is a slightly different form of cellular division in multicellular organisms. This doesn’t happen in all cells, in fact it only happens in your sex cells (sperm & eggs). 

A big difference between mitosis & meiosis, is that the daughter cells only contain half the amount of DNA of the mother cell. This is so, that when a sperm and egg meet, they each bring half the amount of DNA required and combine to make a cell with all the DNA required. 

Try the activity below. 

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