Clarification - primary vs secondary lysosomes

1) Origin of Primary lysosomes (page 17 of your notes I believe)

In your cell structure and function lecture notes, under the section on Lysosomes, it states that primary lysosomes bud off from the Golgi Apparatus OR Endoplasmic Reticulum.

Note that primary lysosomes largely originate from the GA, that is why we have emphasized this during the lecture/tutorial. In some cases, primary lysosomes can bud off the ER but you do not need to know this in detail.

Even if you mention just GA alone, it is still correct. :)

2) Primary vs Secondary lysosomes (tutorial structured Q1d)

- Primary lysosome are formed from the GA while the secondary lysosome is formed by the fusion of the primary lysosome and an endocytotic/phagocytotic vesicle.

- The primary lysosome does not release its contents out of the cell but the secondary lysosome may release useful products (which will serve as building blocks of new materials) into the cytoplasm of the cell via facilitated diffusion, or release waste products/products that cannot be digested out of the cell via exocytosis.

You can view a good diagram of primary and secondary lysosomes here: http://biology.kenyon.edu/HHMI/Biol113/lysosomes.htm