Make your own free website on



The cell membrane is also known as the plasma membrane. It separates the cell from the outside environment. The membrane allows some molecules to pass through but holds others at bay. That is why it is also known as a selectively permeable membrane. The membrane is usually about 7.5 to 10 nanometers thick.


The cytoplasm is the water-like substance found inside the cell. It surrounds the organelles and has water, salts, and organic molecules inside of it. The cytoplasm is constantly moving as molecules and organelles move around. This is known as cytoplasmic streaming.


The ribosome is the most common organelle in the cell. The ribosomes make the proteins for the cell. Each ribosome is a spherical building about 15 to 20 nanometers in diameter. It has 3 nucleic acids in it and over 50 proteins. Where the proteins are located depends on what the proteins are for.


The ER is a big collection of folded sacs and tunnels. The rough ER has ribosomes on it making it bumpy. The smooth ER has little or no ribosomes and is a intercellular highway. It can also serve as a storage area.


The golgi apparatus is the structure where the processing, packaging, and secreting of the organelle in the cell. It is made out of a stack of membranes or sacs filled with fluid and dissolved or suspended substances. The golgi apparatus is like a production line in a factory, where the prodduct is made, packaged, and finally shipped out of the golgi apparatus.


The mitchondria makes all the power for the cell. It is also the respiration center of the cell. Chemical reactions release the energy form the nutrients. It has a membrane to separate the surface of the mitochondria from the cytoplasm. The mitochondria makes the ATP. Mitochondrias are more numerous in cells that use a lot of energy, like muscle cells.


Organelles that have small digestive enzymes are known as lysosomes. These are small sphereical organelles are encircled by 1 membrane. These enzymes digest food particles, disease causing bacteria ruptured by the white blood cells, and worn out broken parts of cells.


Microtubules are long, slender protein tubes, and fine protein threads are microfilaments help share and support cells. Altogether they form the cytoskeleton, the fdramework of the cell. They are made when needed then broken down to make new structures. Some special microtubules are spindle fibers.


Cilia are short almost-hari like structures. Flagella are like tails and they only occur singly or in pairs. Cilia are on the outside of the cell and help with the movement. Flagella are used in such things as the male sperm cell.


The nuclear envelope is a double membrane protecting the nucleous from the cytoplasm. Molecules may enter and leave through the nuclear pores. Inside of the nuclear membrane are chromatin and chromosomes.


The nucleous is located inside of the nuclear envelope. It is a spherical structure that partially synthesize and assemble ribosomes which move out to the cytoplasm. The nucleous is also the "head" of the cell.


The cell wall is a rigid covering of the outside of the cell and it helps suport and protect the cell.


Vacuoles store enzmes and waste products. In a mature cell it takes up about 90% of the cell. It is similar to the lysosomes.


Plastids store food or pigments, which make the plant green or whatever color it is.