##### Explosive Potential!

Say that it takes 20 minutes for a bacterium to replicate. So after 20mins the one cell has become 2, and after another 20 minutes those two have both replicated to 4 and so on.

Within... | Population of ... |

an hour | 8 |

2 hours | 64 |

4 hours | 4096 |

8 hours | 16 777 216 |

16 hours | 281 474 976 710 656 |

And within a day there will be 4.72 x 10^{21} (4 722 366 482 896 650 000 000 000 or 472 million million million) bacteria cells.
And assuming the mass of each bacterium is 1 picogram, by the end of 2 days the bacteria would be pver 3 times the mass of the earth

But this unimagineably huge is stunted by our old favourite: **limiting factors!**

##### Population graph

This graph shows how the population of yeast or bacteria changes over a period of time.

**1. Lag Phase**

There are a small number of microbes and this initial growth is slow.

**2. Exponential Growth**

There is a surplus of resources like food and oxygen so the population
booms.

**3. Stationary Phase**

The rate of cells dying is equal to the rate of new ones being produced.

**4. Death Phase**

All of the nutrients have been used up; toxic material has built up and so the
population plummets with very few new cells and rapid death.