LYSOSOMES AND CELLULAR DIGESTION

Question 1

what is a lysosome?

Answer 1

an organelle of the endomembrane system that contains digestive enzymes capable of degrading all the major classes of biological macromolecules (lipids, carbohydrates, nucleic acids, and proteins)

Question 2

what do the hydrolytic enzymes in the lysosome degrade?

Answer 2

degrades extracellular materials brought into the cell by endocytosis and intracellular structures and macromolecules that are ‘damaged’ and no longer needed

Question 3

structure of lysosome?

Answer 3

vary in size and shape but are usually about 0.5 micrometers in diameter, bound by a single membrane

Question 4

lysosomes contain? (more specific)

Answer 4

acid phosphatase and several other hydrolytic enzymes

Question 5

what protect the lysosome from the hydrolytic enzymes?

Answer 5

the lumenal side of the lysosomal membrane is highly glycosolated, forming a nearly continuous carbohydrate coating that appears to protect the membrane proteins from lysosomal proteases

Question 6

what do ATP dependent protons pumps in the membrane maintain?

Answer 6

an acidic environment (pH 4-5) within the lysosome

Question 7

what does the acidic environment inside the lysosome favor?

Answer 7

favors enzymatic digestion of macromolecules both by activating acid hydrolases and by partially denaturing the macromolecules targeted for degradation

Question 8

what happens to the products of digested macromolecules/structures by hydrolytic lysosomal enymes?

Answer 8

products of digestion are then transported across the membrane to the cytosol, where they enter various synthetic pathways or are exported from the cell

Question 9

there are numerous enzymes inside lysosomes, all are…

Answer 9

acidic hydrolases

Question 10

what is the final step of lysosome development? when does it occur?

Answer 10

• activation of the acid hydrolases
• as the internal environment becomes more acidic through the pumping of protons or through fusion with an existing lysosome