Peroxisomes

Question 1

Formation

Answer 1

1. either budding off endoplasmic reticulum and filling it with the necessary compounds
2. or existing peroxisomes imports free proteins (grows itself)
   - either way you form 2 daughter organelles from fission

Question 2

Peroxisomes

Answer 2

• membrane bound organelles in the cytoplasm of eukaryotic cells
• key role in biomolecule oxidation
• NOT lysosomes
• 0.2-1 micrometer
• urate oxidase crystalline core at a high concentration

Question 3

Protein Import

Answer 3

• Often Ser-Lys-Ley at C-terminal of protein (like catalase)
• Proteins do not need to be unfolded
• Soluble receptors in cytosol + receptor on peroxisome import via a translocator needs ATP

Question 4

Diversity

Answer 4

• abundant in liver and kidney and can change in number

- diverse set of enzymes like oxidative enzymes

Question 5

Functions

Answer 5

• uses oxygen to oxidise (+ remove) organic substrates to make water
• catalase uses hydrogen peroxide to oxidise phenols, formic acid, alcohol, and formaldehyde
• penicillin biosynthesis
• cholesterol biosynthesis
• synthesis of plasmalogens

Question 6

Beta-oxidation of Long Chain Fatty Acids

Answer 6

Uses acetyl CoA oxidase, ACO to release energy

Question 7

Clinical Relevance

Answer 7

Zellweger Syndrome = empty peroxisomes due to mutations in import proteins
X linked adrenoleukodystrophy = can’t import VLCFA in, harmful to myelin
Shai et al (2018) = peroxisome and mitchondrial contact site research