Cells are the basic unit of life. Every living thing on the planet is composed of cells. Humans, trees and fish have trillions of cells, while bacteria and yeast are single celled organisms. But what is a cell?
Cells can be split into two categories, prokaryotic and eukaryotic, based on some key characteristics.
- Prokaryotic cells are found in bacteria (called prokaryotes) and can be thought of as simpler cells. They don’t contain a nucleus and do not have very many organelles (or small organs). The DNA in prokaryotic cells is free floating and is not contained to chromosomes.
- Eukaryotic cells are found in multicelluar organisms, like humans, but also in unicellular organisms, like yeast. These organisms are collectively called eukaryotes. People often consider them to be more complex than prokaryotic cells and are likely evolved from prokaryotic cells. They contain a nucleus with their DNA contained in chromosomes. They also have many organelles.
Cells are little factories that make life possible. They convert food into energy. They make proteins to help you digest food. They grow and divide to help you grow or repair wounds. They contain equipment called organelles in order to perform these tasks. These include:
- Mitochondria, the energy factory of the cell.
- Ribosomes, where proteins are made.
- Endoplasmic reticulum, where proteins are modified or drugs are destroyed.
- Golgi apparatus, the shipping facility of the cell.
- Nucleus, which contains all the genetic information.
The organelles that a cell contains depends on the function it is meant to perform. Liver cells have more organelles to help it detoxify the body while muscles have more organelles to help it make energy for contraction.
Future BioBits will go into the functions of various organelles within the cells. For now, here is a good video.