Cells are divided into two categories: prokaryotes and eukaryotes. Bacteria and archaea are prokaryotic cells. All other cell types like animal, plants, fungi, and protists are eukaryotic cells.
Prokaryotic cells were the first cells to appear on the planet. Eukaryotic cells evolved from prokaryotic cells much later on in the history of our planet.
“Pro” means “before” and “kary” means “nucleus”. So prokaryotes are cells that were present before the nucleus came about. In other words, prokaryotes do not have a nucleus. “Eu” means “true”, eukaryotes have a true nucleus. Both cells have DNA but it looks different and is housed in different areas of the cell.
Prokaryotes have circular DNA that floats in the nucleoid. Nucleoid means “nucleus-like”. It’s an area in the cytoplasm where DNA will be found. Eukaryotes have strands of chromosomes that are found in their nucleus.
There are several differences between prokaryotes and eukaryotes but the main difference is that prokaryotes do not have membrane-bound organelles, whereas, eukaryotes do. There are several organelles within the cell that are surrounded by a plasma membrane (much like the cell itself is surrounded by a plasma membrane). Prokaryotes do not have these organelles. This means that prokaryotes do not have nuclei, mitochondria, endoplasmic reticulum, lysosomes, centrosomes, chloroplasts, and Golgi apparatus.
Furthermore, prokaryotes will have a plasma membrane as well as a cell wall. Their cell wall is made of peptidoglycans. Most will also have a polysaccharide capsule that helps them attach to surfaces around them.
Some prokaryotes have flagella (that help them move), pili (that help in transferring genetic material during reproduction), or fimbriae (that help them attach to a host cell).
Prokaryotes are much smaller than eukaryotic cells. Prokaryotes are 0.1 to 5.0 μm in diameter, whereas, eukaryotes are 10 to 100μm.
Prokaryotes are usually unicellular organisms, eukaryotes can be unicellular or multicellular.
Prokaryotes and eukaryotes will contain plasma membrane, cytoplasm, and DNA.
They both also contain ribosomes but prokaryotes have much smaller ribosomes than eukaryotes. Prokaryotes contain a cell wall, some eukaryotes- like plant cells- will contain a cell wall as well.
Prokaryotes contain flagella, some eukaryotic cells (like sperm cells) can have flagella but prokaryotic flagella is much smaller.