PEROXISOMES

Question 1

peroxisome structure and origin (or lack of)

Answer 1

bounded by a single membrane and not derived from the ER, therefore not apart of the endomembrane system

Question 2

what do they contain that is unique to them? what does it do?

Answer 2

contain the enzyme catalase, which is essential for degradation of hydrogen peroxide

Question 3

what is hydrogen peroxide?

Answer 3

a potentially toxic compound that is formed by a variety of oxidative reactions catalyzed by oxidases

Question 4

both oxidase and catalase are confined to peroxisomes, this means…

Answer 4

that generation and degradation of H2O2 occur within the same organelle, thereby protecting other parts of the cell from exposure to H2O2

Question 5

what did researchers use to isolate specific cellular components?
what did they identify?
what did this region of the gradient contain?

Answer 5

• a gradient of sucrose concentration
• identified a region distinct from known organelles that contained the enzyme urate oxidase
• this region of the gradient contained peroxisomes

Question 6

what does catalase do to diaminobenzidine (DAB)?

how can these electron dense regions be seen?

Answer 6

catalase oxidases DAB to a form that causes deposition of osmonium ions
can be seen via electron microscopy

Question 7

Peroxisome structure (more specific)

• in animals?
• in plants?

Answer 7

in animals:
crystalline core, consisting of crystalline urate oxidase
in plants:
contain crystalline catalase