Lecture 6: Peroxisomes

Question 1

Learning Objectives

Answer 1

• What is the structure of peroxisomes?

- What do peroxisomes do?

Question 2

What are the functions of peroxisomes?

Answer 2

• break down very long chain fatty acids
• oxidise amino acids/fatty acids (beta oxidation breaks down fatty acids)
• detoxify molecules entering the bloodstream in liver and kidney cells
• synthesis of penicillin, cholesterol, bile acid, myelin lipids
• break down of excess purines (AMP, GMP)
• break down xenobiotics (chemicals which shouldn’t be in that organism)

Question 3

Which enzymes and chemicals do peroxisomes contain?

Answer 3

• Hydrogen peroxide (broken down by catalase)
• catalase
• urate oxidase
• oxygen

Question 4

What is the signal which tags a protein for import into a peroxisome?

Answer 4

Ser-Lys-Leu

Question 5

How are peroxisomes formed?

Answer 5

• Budding off the ER

- existing peroxisomes expand and divide

Question 6

How are proteins imported into the peroxisome?

Answer 6

Proteins are translocated using a translocater using ATP. The proteins do not need to be unfolded.