All living things are made up of cells, the structured units of life.
There are 2 major types of cells:
1. PROKARYOTE CELLS
– They were the first cells on earth.
– Bacteria are major examples of Prokaryote cells.
– They are more primitive than Eukaryote cells.
– They appeared in evolution before nuclei had evolved. So they are simpler in their
– Even though they have a simpler structure than Eukaryote cells, they adapt quickly to
– They do not have a nuclear membrane; instead they have a nuclear area, known as the nucleoid
that carries the cell’s DNA.
– They divide by binary fission.
– The two daughter cells that are produced are clones of each other. There is no genetic
variability, unless a mutation has occurred.
– They do not have membrane bound organelles.
– They have no mitochondria. Golgi bodies, lysosomes or vacuoles.
– The ribosomes are structurally different from the ribosomes of Eukaryote cells.
– Like Eukaryote cell, Prokaryote cells have a cell membrane.
– They also have a rigid cell wall, a protective barrier on the outside of the soft cell
– Metabolism can take place in the presence of oxygen (aerobic) or not (anaerobic) depending on
the cell type and species.
2. EUKARYOTE CELLS
– They make up the cells of nearly all other organisms on earth, except bacteria. Most plants
and animals have a more complex structure than bacteria (Prokaryote cells).
– They are larger that Prokaryote cells.
– They have a nucleus that is enclosed in a nuclear membrane, where the genetic material is
– They have many membrane bound organelles, like mitochondria, Golgi bodies, endoplasmic
reticulum, lysosomes and vacuoles.
– The organelles allow the Eukaryote cell to perform various chemical reactions within the cell
in specific locations.
– Cell division is either by mitosis or meiosis.
– A cell wall may occur in some species, but it’s chemical structure differs from the
Prokaryote cell’s cell wall.
– Metabolism is usually aerobic (in the presence of oxygen).