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The Cell Theory

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The Cell Theory

The cell theory states that all living matter is made up of cells and some living organisms consist of a single cell. Other cells serve a special purpose within advanced organisms like nerve cells. One theory of a cell states that the first form of life on this earth consisted of a lot of different types of small protocells. Protocells are cell like organism. These organisms were able to reproduce in a very limited environment because they are so simple. After many years some of the protocells came together and shared their DNA with each other. These protocells eventually became the cells we are studying now.

Type of Cells

There are two types of cells one is the Prokaryote, a Prokaryote is a cell with no nucleus or organelles with membranes, the other, a Eukaryotes are cells that contain a nucleus and organelles and are surrounded by a membrane

Cell Structure

Thin membranes surround cells; this is called the cell membranes, they separate the inside from the out. The cell membrane is just like the other organelles in a cell because it has its own specialized jobs. One of its jobs is to control what enters and exits the cell and to protect the cell. Cell membranes are made up of fats with big protein molecules inside them. Molecules move across cell membranes by two processes diffusion or active transport. Diffusion is the movement from a high level of molecules to a low level of molecules. Molecules can diffuse across membranes through the phospholipid bilayer or using a protein. Either kind of diffusion does not need energy from the cell. Some special proteins move certain molecules across cell membranes only with the help of cell energy. Moving molecules with cell energy is called active transport. When water diffuses the process is called osmosis. Water moves from a high level of water (to a low concentration of water. This means that water would cross a selectively permeable membrane from a dilute solution to a concentrated solution. Water can cross the cell membrane through the lipid bi-layer and with special proteins. If enough water enters the cell by osmosis, the cell can swell enough to burst open and die.

Function Relationships

The cell is the most advanced molecule. The cell is so small, it is microscopic, yet each cell functions as part of a big family that controls your body. Each cell has its own organelles;



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