Prokaryotic and Eurkaryotic cells

There are two different types of cells, prokaryotic and eukaryotic.

Prokaryotic cells make up prokaryotes. Prokaryotes are single celled or unicellular organisms and an example is bacteria.

Eurkaryotic cells make up eukaryotes. Eukaryotes are multicellular organisms. Examples of eukaryotes include all plants and animals.

One of the key things to remember is that prokaryotic cells are always much more simpler than eukaryotic cells which are much more complicated and filled with many more parts.

Despite this, both types of cells have things called organelles. Organelles are parts of the cell and they all have a specific purpose/ job/ function to perform.

Prokaryotic cells

• really small cells- less than around 2 micrometres in diameter.
• the DNA in the cell is in the cytoplasm and so it kind of hangs around freely. This is because prokaryotic cells don't have have a nucleus
• the cell wall is a key feature in prokaryotic cells. It's made up of polysaccharide.
• there are no mitochondria inside the cell at all and there there are very few organelles in the cell anyway.
• teeny tiny ribosomes

Eukaryotic cells

• larger cells- about 2-250 ish micrometres in diameter.
• the DNA is found in the nucleus rather than the cytoplasm. The nucleus is usually always present in eukaryotic cells.
• In animal cells, there is no cell wall. In plants, there is a cell wall and it's made of cellulose.
• Eukaryotes have lots and lots of organelles. They also have mitochondria too.
• Quite large ribosomes.

What's a micrometre?

It's a unit of measurement for cells but there are other measurements sometimes also used like nanometres.

As a rough guide though, one micrometre is the same as one millimetre (0.001mm)

*Different textbooks, teachers, powerpoint slides etc may have slight variations on how big or small something is when it's measured in micrometres. This is ok, it's just because different microscopes are used by textbooks, teachers, powerpoint slides etc when it comes to measuring things and so variations happen.

For example, at school, a past paper we did as a class had a huge variation with the information provided in our school textbooks.

Ultimately though, as long as you know that prokaryotic cells and things inside them are super small in comparison to eukaryotic cells, you should be fine.