*If you have any questions based on this post, please send me a comment on this website, along with your question(s).
It’s all about the cells….(Prokaryotic cells)
Cells make up living organisms such as plant and animal cells .This includes your pet dog, your mums and dads and yourself. In AS Level we talk about two types of cells in particular in which all cells that make up the things around you are categorised. These cells are called prokaryotic and eukaryotic cells.
There are many differences between these cells, of which I will be talking about in the following paragraphs.
Prokaryotic cells (pronounced pro-carry-oh-tick) cells are small and simple cells. This word comes from the suffix ‘Pro’ meaning ‘before’ and ‘karyon’ meaning ‘nucleus’ or , if you put them together before (the nucleus).This is because scientists believe that prokaryotic cells existed before cells developed nuclei due to evolution. Prokaryotic cells such as bacteria are known for causing diseases, one of which is called MRSA(methicillin resistant staphylococcus aureus), but some are useful and are used to treat sewage and produce medicines.
Prokaryotic cells make up unicellular organisms, or in other words, prokaryotic cells are unicellular organisms. They have the ability to carry out the functions of life (MRS GREN; Movement, respiration, sensitivity, etc.). As simple cells, they do not contain many organelles and no mitochondria are found there at all! In GCSE, you may have heard of the famous mitochondria, the ‘powerhouse’ of a cell, where energy is released for functions of the cells (e.g. active transport) and, in general, for starting off vital chemical reactions in the cells but prokaryotic cells do not have this lovely double membrane bound organelle containing enzymes involved in respiration .
The question is, though, that if prokaryotic cells are living and carry out chemical reactions which require energy such as, how they get energy for these things, do chemical reactions even take place in prokaryotic cells? Where do these simple cells get the energy for cell division and the synthesis of new organelles?
This is where I introduce you to a new organelle called the mesosome. If you haven’t heard of this organelle, don’t worry, it is just extra information and not part of the AS level specification (I assume) but it’s an interesting organelle nonetheless.
The mesosome is simply a simpler form of mitochondria. It is an infolding of the cell membrane of the prokaryotic cell and like the mitochondria, contains enzymes involved in respiration, it just doesn’t consist of a double membrane, but a single and simpler arrangement is used instead. Being simple, prokaryotic cells do not have many organelles and all the organelles which they do have are not double membrane bound.
As well as having no mitochondria, they also contain smaller ribosomes compared to eukaryotic cells, cell walls made out of polysaccharide(carbohydrates) other than chitin, found in the cell walls of fungi, and cellulose (found in the cell walls of plant cells).
Or in other words, the mesosome is the organelle labelled with the number 9 on the image below (This image is an example of a prokaryotic (unicellular) cell , bacteria.
Their genetic materials (DNA), unlike the eukaryotic cells, are not found in the nucleus but float freely in the cytoplasm. They are also circular; another name for circular DNA is ‘nucleoid’, by the way. They also contain 70s (very small) ribosomes while eukaryotic cells contain 80s (bigger) chromosomes.
I hope this blog post has been useful. If you have found this helpful, have a look out for my next blog post:
‘It’s all about the cells (Eukaryotic cells)’.
The Sciency Fellow 