In this video, we are going to have a look at the similarities and differences between prokaryotic and eukaryotic
cells. All cells are either prokaryotic or eukaryotic.
Organisms with prokaryotic cells are called prokaryotes. And organisms with eukaryotic cells are eukaryotes.
Bacteria and archaea are prokaryotes. Whereas plants, animals, fungi and all other organisms are eukaryotes.
If the genetic material is enclosed by a nuclear envelope, so giving a definite nucleus, then they are
eukaryotic. Like this animal cell. Whereas in prokaryotic cells there isn't a nuclear membrane, and so no definite nucleus.
The DNA Is in the cytoplasm!
We call a nucleus without a nuclear membrane a 'nucleoid'.
It isn't really a structure at all. It is simply the area in which the DNA exists.
Prokaryotes were the first type of organism to evolve. And still the most common organisms today.
It Is believed that the eukaryotes are evolved from prokaryotes.
So the nucleus is a key factor in identifying whether the cell is prokaryotic or eukaryotic,
but also the other organelles are too.
Organelles are tiny structures within the cytoplasm that perform specific jobs,
like the energy providing mitochondria in the animal cell. Eukaryotic cells contain lots of different organelles.
Whereas ribosomes are the only organelles found in prokaryotic cells. Ribosomes are where proteins are made.
Organelles are very important to eukaryotic cells. Bacteria can get by without them because
they are so small. Eukaryotic cells are still too small for our naked eyes, but they are huge in comparison to prokaryotic cells.
Organelles are an efficient way for eukaryotes to organise everything that is happening inside the cell. The cellular functions are compartmentalised.
This means that different organelles carry out different processes. But bigger doesn't necessarily mean better!
It is the small size and simplicity that is an advantage to prokaryotes.
It suits their lifestyle being small. It mean they have a large surface area to volume ratio, and
they can easily meet their nutritional needs to grow quickly and multiply rapidly.
So, we know that prokaryotes don't have a nucleus and lack most other organelles. A final thing to discover
is that all prokaryotes are unicellular. They are defined as unicellular organisms that lack a membrane-bound nucleus.
Eukaryotes can bee either unicellular or multicellular. We looked at the differences between unicellular and multicellular in this video...
The Statement that all "prokaryotes are unicellular" is up for discussion however.
There is a lot of evidence that shows that
bacterial species can aggregate together and divide labour. Thus forming a colony of cells that work more efficiently. This is a multicellular
characteristic. However, there is a lot of resistance to calling any prokaryote multicellular.
So there we have nucleus-free prokaryotes and nucleus containing eukaryotes. These are the main points from this video...
