Lysosomes Develop from Endosomes

Question 1

(Step 1) lysosomal enzymes are synthesized by? and then are translocated through?

Answer 1

• synthesized by ribosomes attached to the rough ER and then are…
• translocated through a pore in the ER membrane into the ER lumen before transport to the Golgi Complex

Question 2

(step 2) after modification and processing in the ER and the Golgi, the lysosomal enzymes are…

Answer 2

sorted from other proteins in the TGN, and from the TGN delivered to endosomes in the transport vesicles

Question 3

(step 3) endosomes mature into…

Answer 3

late endosomes, with all the enzymes, but not engaged in digestive activity

Question 4

(step 4) the final step in lysosome development is the…

Answer 4

activation of the acid hydrolases, which occurs as the enzymes and their substrates encounter a more acidic environment

Question 5

what are two ways euk. cells accomplish the last step…(encountering a more acidic environment)

Answer 5

1. ATP dependent proton pumps may lower the pH of the late endosome lumen to 4-5, transforming the late endosome into a lysosome
2. late endosomes may transfer material to the acidic lumen of the existing lysosome

Question 6

Lysosomal Enzymes are Important for Several Different Digestive Properties: Lysosomes have multiple origins (2)

Answer 6

1. heterophagic lysosomes - those containing substances that originated outside the cell
2. autophagic lysosomes - those containing substances that originated inside the cell