The Importance of cell division Reproduction Growth Repair & Replacement

More then 100 Trillion Cells How do we get from this To this 2 Cells 1 Cell - Zygote More then 100 Trillion Cells To this To this

We will get to that soon but first… Who Cares???? Why do we need to have cell division? What did it ever do for you? There are 3 main reasons for cell division Reproduction Growth Repair/Replacement

1) Cell Division for Reproduction It is an important characteristic for life All living things must reproduce Each time a cell divides it produces two new cells which can be: Identical  Asexual reproduction (Mitosis) Different  Sexual reproduction (Meiosis)

2) Cell Division for Growth All living things must grow When a multicellular organism grows it increases its number of cells A unicellular (one cell) organism will enlarge its size slightly How large will the cell get? Why aren’t we made of one or a few big cells?

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Cell Division for Growth All cells need Oxygen, Water and Sugar which needs to be transferred to and through the cell Cells also need to transfer CO2 and other waste products out of the cell

Cell Division and Growth The movement of substances through the cell occurs by diffusion from an area of high concentration (more) to an area of low concentration Why does this impact cell size???????

Cell Size When a cell gets too large, chemicals and water cannot move fast enough to get where they need to go This would cause the cell to either die from lack of nourishment (no O2 or sugar) or from poisoning (no waste removal)

3) Cell Division for Repair & Replacement Every day, your body sheds millions of dead skin cells and then replaces them. Your body replaces red blood cells about every 120 days Cuts and broken bones need to be healed