Cell Types and Classification

Study Notes

There are many different types of cells, including blood cells, skin cells, bone cells, and bacteria.
Despite the variety, all cells can be classified into two general types: prokaryotic cells and eukaryotic cells.

A basic cell structure present in many living cells is the nucleus, a structure in the cytoplasm that contains and protects most of the cell's DNA.
The nucleus is surrounded by a membrane called the nuclear membrane.

Eukaryotic cells are cells that contain a nucleus.
They are usually larger than prokaryotic cells and are found mainly in multicellular organisms.
Eukaryotic cells contain other organelles besides the nucleus, such as mitochondria (provide energy) and vacuoles (store substances).
Organelles allow eukaryotic cells to carry out more functions than prokaryotic cells.
Examples of organisms with eukaryotic cells include fungi, animals, protists, and plants.

Prokaryotic cells are cells without a nucleus.
The DNA in prokaryotic cells is in the cytoplasm, rather than enclosed within a nuclear membrane.
Prokaryotic cells are found in single-celled organisms, such as bacteria.
Examples of organisms with prokaryotic cells are called prokaryotes.
Prokaryotes were the first type of organisms to evolve and are still the most abundant organisms today.

Ribosomes, the cellular structures where proteins are made, are found in both eukaryotic and prokaryotic cells.
The cell membrane is filled with cytoplasm, which contains various structures, such as a nucleus and other organelles.