Prokaryotic vs Eukaryotic Cells

Bacteria cells are prokaryotic, and all other cells are eukaryotic. the biggest difference between them is that eukaryotic cells have a membrane-bound nucleus and membrane-bound organelles, whereas prokaryotic cells have neither a membrane-bound nucleus nor membrane-bound organelles. Prokaryotic cells (0.1-10 micrometres) are generally smaller than eukaryotic cells (10-100 micrometres).

There are many benefits to having membrane-bound organelles. The first is that it allows for more control of what is allowed in and out of the different cellular compartments. For example, the nuclear envelope stops chemicals that would otherwise damage the DNA from entering the nucleus. The second benefit is that it enables the cell to keep millions of chemical reactions that are occurring at any given moment from interfering with each other. This does not necessarily mean that bacteria are worse off, they are simply too small to fit membrane-bound organelles. A useful fact when it comes to designing antibiotics.

I have gone through the structure of eukaryotic cells in a previous post so I will touch on some aspects of the prokaryotic cell.

Chromosomal DNA – the DNA in bacteria is not in a nucleus but rather found in the cytoplasm. It still undergoes most of the same processes as nucleic DNA but with a few differences.

Plasmid – a plasmid is a circular piece of DNA that can replicate independently of chromosomal DNA. They can provide bacteria with genetic advantages, such as antibiotic resistance. Not all bacteria have plasmids.

Flagella – a flagellum is a whip-like structure that enables bacteria to move. Bacteria can have more than one flagella. They are not limited to prokaryotes but are found in all branches of life.

Capsule (not shown) – the capsule is a layer of polysaccharide that sits outside the cell wall. It offers another layer of protection for the bacteria. Not all bacteria have a capsule.

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