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.
MICROTUBULES AND MICRFILAMENTS
CILIA AND FLAGELLA
CELL WALL (PLANT ONLY)
VACUOLES (PLANT ONLY)
PLASTIDS (PLANT ONLY)