My notes

• Cells are very complex structures, with differences between plant and animal cells:

  • Animal cell components: ribosome, nuclear envelope, nucleolus, chromatin network, centriole, centrosome, pinocytic vesicle, pinocytic invagination
  • Plant cell components: dictyosome, nuclear envelope, nucleolus, chromatin network, vesicle
• Organelles are the structures inside cells, and a group of cells with similar structure and function is called a tissue
• Levels of organization in an organism:

  • Cells are composed of organelles
  • A group of cells with similar structure and function is a tissue (e.g., muscle tissue)
  • A group of tissues acting together is an organ (e.g., skin)
  • A group of organs acting together is an organ system (e.g., thermoregulatory system)
  • Many systems acting harmoniously make up an organism
• Some organisms are unicellular, like bacteria, Paramecium, and Amoeba, while others, like humans, are multicellular