Peroxisomes

Question 1

What are peroxisomes?

Answer 1

Peroxisomes are membrane-bound vesicles that contain a specific set of enzymes.

Question 2

How big are peroxisomes in diameter?

Answer 2

Peroxisomes can be everything between 0.1 - 1 um in diameter?

Question 3

Mention some important peroxisomal enzymes.

Answer 3

1. Peroxisomal oxidases
2. Catalase
3. Fatty acid beta-oxidation enzymes
4. Lipid-synthesizing enzymes.
5. Aminotransferases.

Question 4

What is the function of the peroxisomal enzyme Catalase?

Answer 4

It catalyzes the decomposition of hydrogen peroxide into water and oxygen.

Question 5

What are the byproducts of peroxisomal oxidases activity?

Answer 5

Peroxisomal oxidases generate hydrogen peroxide as a by product.

Question 6

What are the main functions of the peroxisomes?

Answer 6

1. Oxidation of substrates.
2. Decomposition of H2O2 (by catalase)
3. Beta-oxidation of long-chain fatty acids.
4. Participation in the synthesis of some lipids (cholesterol, plasmalogens) and some bile salts.
5. Participation in degradation of purines.

Question 7

How are the peroxisomes made?

Answer 7

ER produces small vesicles with peroxisomal membranes. Other proteins and enzymes are posttranslationally incorporated into the vesicles and peroxisomes are formed.

Question 8

Peroxisomes participate in the synthesis of some molecules. What molecules and compounds is this?

Answer 8

Peroxisomes participate in the synthesis of some lipids (cholesterol, plasmalogens) and some bile salts.