BIO 12 Cell Processes Project Part III: Digestion

• Endocytosis is a process in which a cell takes in material from the outside by engulfing and infusing them with cell membrane:
• Most of this external material are large polar molecules such as proteins which are unable to pass through the membrane via diffusion
• There are 2 major types of ENDOCYTOSIS: phagocytosis (cell-eating) and pinocytosis (cell-drinking)
• Lysosomes are specialized vesicles from the Golgi apparatus that have specialized digestive enzymes. Their role in the digestion of incoming nutrients are to break them down after they have entered the cell by the aforementioned process of ENDOCYTOSIS. This is crucial in ensuring that the harmful substances which are a part of the discussed material is dealt with appropriately.

• Vacuoles are part of the main type of intracellular digestion which is heterophagic:
• Specialized vesicle-like structures called Phagosomes or Pinosomes (depending on the process that occured) fuse with lysosomes to create digestive vacuoles:
• The materials inside of this 'special' vacuole undergo hydrolisis and the products of these reaction are either stored in the vacuole or they reach the cytoplasm of the cell
• The residual material left in a vacuole after digestion will eventually undergo EXOCYTOSIS (opposite of "ENDO") under the larger process SECRETION