Prokaryote means ‘before the nucleus’, which means the DNA isn’t contained inside of the membrane.
Prokaryotic cells have appeared in fossil records from 3500 million years ago and are made up of a variety of organisms known collectively as bacteria.
Prokaryotic cells are smaller and less complex than eukaryotic cells. Prokaryotic cells have no nuclear membrane; the nuclear membrane is a very porous membrane that allows molecules to easily pass freely from the cytoplasm. The chromosomes in a prokaryotic cell are in direct contact with the cytoplasm. In comparison the chromosomes are enclosed in a double-layered nucleus membrane. They also have a much more complicated chromosome structure compared with prokaryotic cells. The cell division that takes place in a prokaryotic cell doesn’t involve the process of meiosis. However, a eukaryotic cell will divide using mitosis and meiosis, yet another difference between these two types of cells.
If present, then the cell wall of a prokaryotic cell will contain peptidoglycan, which are carbohydrate polymers cross-linked by proteins. In contrast with eukaryotic cells, if a cell wall is present, it will contain cellulose or chitin. Chitin is a polysaccharide, as is and , both similar in chemical structure to . Like cellulose, chitin contributes strength and protection to the organism. So eukaryotic cells are often stronger than prokaryotic cells.
Eukaryotic cells usually contain mitochondria, which are the site of aerobic respiration, and they absorb glucose and oxygen. They also provide energy, which is transferred in cells. However these aren’t present in prokaryotic cells. Chloroplasts are present in photosynthetic cells. Ribosomes are organelles found in both prokaryotes and eukaryotes. There are two types in eukaryotic cells. One is found in the cytoplasm, which is the region between the nucleus and the cell membrane and the other, smaller type is found in the mitochondria. The prokaryotic cells only contain one type of ribosome of one size.
Flagella, if present in eukaryotic cells, have a complex structure, both structurally and bio chemically. But on the other hand if they are present in prokaryotic cells then they have a much simpler structure. The size of these two types of cells is different too. Eukaryotic cells have up to one thousand times more volume than a prokaryotic cell.
Both eukaryotic and prokaryotic cells have DNA as their genetic material; they also both contain ribosomes and a membrane bound. They have very similar basic metabolisms.
Prokaryotic and eukaryotic cells have evolved. Data supports the theory that prokaryotic cells represent the initial cell type on earth and that the eukaryotic cells have evolved from them.
