Cells are the basic unit of life. All living organisms are composed of one or more cells. In this section, we will cover:
Cells have three main components: the cell membrane, cytoplasm, and genetic material. The cell membrane is a semi-permeable barrier that controls what enters and exits the cell. The cytoplasm is a jelly-like substance where chemical reactions occur. Genetic material, DNA, contains instructions for cellular functions.
There are two main types of cells: prokaryotic and eukaryotic. Prokaryotic cells, like bacteria, lack a nucleus and other membrane-bound organelles. Eukaryotic cells, found in plants and animals, have a nucleus and other specialized structures called organelles.
Eukaryotic cells contain several important organelles:
Cells reproduce through a process called cell division. The two main types of cell division are mitosis and meiosis. Mitosis produces two identical daughter cells, while meiosis produces four sex cells (gametes) with half the normal number of chromosomes. Mitosis enables growth and repair, while meiosis allows for sexual reproduction.