Cell Types and Classification

Types of Cells

• 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.

Cell Structure

• 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

• 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

• 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.

Cellular Structures

• 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.