3. Cell Membrane While not an organelle by definition, the cell membrane certainly requires mention. It also acts as the “doorman” to the cell, allowing certain materials to pass through easily, but denying other, potentially harmful, objects access to the inside of the cell. The cell membrane creates an enclosure around the cell, creating a stable environment for the rest of the organelles to function properly.
4. Nucleus The nucleus acts as the control center of the cell. You can clearly see it in almost every cell you look at through a microscope, because it is filled with twisted chromosomes. The nucleus is spherical in shape, and is surrounded by the nuclearmembrane and encloses the nucleolus.
5. Mitochondria The mitochondria convert incoming food molecules into a usable energy source, ATP. Popular cliché is that the mitochondria are the “powerhouses” of the cell. They are oval in shape, and have a double membrane with inner folds called cristae. The mitochondria also control water levels and are in charge of recycling usable material.
6. Golgi Apparatus The Golgi Apparatus is primarily used for packaging materials entering and leaving the cell. If Mitochondria are the powerhouses, then the Golgi Apparatus the packaging plant. Many layers of membrane form sacs that reside close to the nucleus for rapid packaging of instructions via the chromosomes in the nucleus.
7. Ribosomes While not large, the ribosomes compose 25% of the cell’s mass. The ribosomes are miniature protein factories that come in two types, attached or free. Both types of ribosome are round and usually dark in appearance. Free ribosomes float around in the cytoplasm, injecting protein directly.
8. Endoplasmic Reticulum The Endoplasmic Reticulum (ER) also has two similar types, Rough, and Smooth. Rough ER has ribosomes embedded in its surface, Smooth ER simply lacks ribosomal attachment. ER attaches from the nuclear membrane to the cellular membrane, acting as the Postal Service of the cell, and transports materials.
9. Lysosomes Lysosomes flow through the cytoplasm acting as recyclers for the cell. (Lys = to cut) These small organelles digest proteins, fats, and carbohydrates within the cell when they can be reused. If a lysosome bursts within a cell, the cell quickly breaks down and dies.
