Biology
Cell Structure and Organelles
Cell: the structural and functional unit of living organisms.
Prokaryotes have no true nucleus (bacteria). Eukaryotes (plants, animals, fungi) have a nucleus.
Organelles
- The plasma membrane regulates the entry of substances into the cell.
- The nucleus stores hereditary information.
- ATP is synthesized in the mitochondrion. It is called the "powerhouse of the cell".
- Protein is synthesized on the ribosome.
- The Golgi apparatus collects substances and secretes them out of the cell.
- Lysosomes contain digestive enzymes.
- The chloroplast is found only in plant cells. Photosynthesis takes place here.
| Organism | Cell wall |
|---|---|
| Plant | cellulose |
| Fungus | chitin |
| Bacterium | murein |
Key Facts
- Endoplasmic reticulum (ER): rough (with ribosomes, protein synthesis) and smooth (lipid and carbohydrate synthesis).
- Mitochondria and chloroplasts have two membranes and their own DNA and ribosomes.
- Cell wall: in plants the wall is made of cellulose, in fungi of chitin, in bacteria of murein.
- The cell center (centrioles) is found in animal cells and forms the spindle during division. A large vacuole is characteristic of the plant cell.
- Fluid mosaic model of the membrane: a lipid bilayer with proteins embedded in it.