The Evolution of Cells

Some Bacteria undergo Endosymbiosis making more complex cells

4000 Billion Years ago the first living cells existed

Over time changes occur to the ancient Bacteria and Archaebacteria

Simple Bacteria still exist

At some stage a Bacteria absorbed another bacteria but did not digest it

This was the Endosymbiosis event

This occured 2500 Million Years ago

Endosymbiosis gave rise to individual organelles within a cell

This allowed more complex life-forms to evolve

Fistly Protists - Single celled organisms that contain organelles

Then Plants

Then Fungi

Finally Animals

Change continues to drive Evolution

More Complex cells are Larger

These new more complex cells are larger than bacteria, as seen in the picture below of a bacteria next to a Red Blood Cell, and in the YouTube clip of a White Blood Cell chasing Bacteria. This is also shown in the sizes in micrometers of the cell sizes for each of 4 Kingdoms in the picture further below

Bacteria vs Plant Cells vs Animal Cells

The image to the side has bacterial cell way larger than it should be compared to the other two relatively huge cell

The simple Bacteria is referred to as a Prokaryote

Only Archaea and Bacteria are Prokaryotes

The complex Animal and Plant cells (as well as Protists and Fungi) are Eukaryotes

You are a Eukaryote

The inclusion of organelles resulted in longer lived cells capable of greater complexity of life

Notice the number of organelles that both animal cells and plant cells have

Notice also the differences

Everything an animal cell has, a plant cell also has, however, plant cells have things that animal cells don't. This is because of photosynthesis and amino acid synthesis

Plants make Everything

Plants are autotrophes -this means they make their own food - all they need is Carbon Dioxide, Water and Sunlight - this makes Glucose and Oxygen

Using the Carbon from the Glucose, they can then make every single other biological molecule, including Simple and Complex Carbohydrates, Lipids, Nucleotides and all of the Amino Acid


Animals on the other hand, need to eat living things in order to get their food. These living things could be other Animals or Plants


The term 'essential amino acids' is a misnomer - all amino acids are essential - however human cells can make some of these from other materials - the essential amino acids are essential for us because we can not make them - we need to eat them - It is plants that make them - This is called Amino Acid Synthesis


Plants make everything!

A few relevant and interesting clips