Life is Cellular
Cells are the most basic units of life. They make up all living things, whether they are bacteria, flowers, or whales. It wasn't until the invention of the microscope that cells were even discovered. Since the discovery of cells, all of the data and evidence that has ever been collected on cells has lead to the development of the cell theory.
What is the Cell Theory?The cell theory was developed from the combined works of Matthias Shleiden, Theodor Schwann, and Rudolf Virchow. The cell theory contains three key points:
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How are cells different?
As the cell theory states, all living things are made up of cells. That does not mean, however, that all cells are exactly the same. There is a large variety of cells that perform countless different functions. For example, brain cells and blood cells have to completely different jobs and structures. Even with the variety of differences among cells, there are only two types of cells, prokaryotes and eukaryotes.
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Eukaryotes
Eukaryotes are the largest and most complex of the two types of cells. Unlike prokaryotes, eukaryotes store their genetic material inside a nucleus. Eukaryotes also contain many different structures, called organelles, and membranes within the cell. These different organelles are what allow eukaryotic cells to specialize and perform specific functions. Most eukaryotic cells join together to create complex living organisms like plants, animals, and fungi. There are some eukaryotes, called protists, that live individually. |
Animal Cells
Eukaryotic cells can be divided into two categories, animal cells and plant cells. While both plant and animal cells are eukaryotes, meaning that they share many similar features, there are some distinct differences between the two types that we will begin to learn about here. We are going to start by learning about animal cells.