Peroxisomes are organelles found in the cytoplasm of plant and animal cells that contain enzymes for oxidizing fatty acids and other organic substances. They produce hydrogen peroxide as a byproduct which is immediately broken down by the enzyme catalase. Peroxisomes play important roles in processes like fatty acid breakdown, bile acid and cholesterol synthesis, and the breakdown of toxic peroxides. Defects in peroxisome function can lead to genetic disorders affecting the nervous system, liver, and other organs.

1. Peroxisomes
Submitted By,
Raghu Solanki
CUG/2014/1069
Life Science
CUG

2. Peroxisome
1. History
2. Introduction
3. Location
4. Origin
5. Importance and Functions
6. Disease
7. Conclusion

3. 1.History

4. History of Peroxisomes
 First observed by electron microscopy in
animal cells (1950s), then in plant cells
(1960s)
 Christian deDuve (1965)
 Isolated from liver cells by centrifugation
 Called them peroxisomes because they
generate and destroy H2O2

5. 2.Introduction

6. The Peroxisome
 Single
membrane
 Roughly
 spherical
 0.2 - 1.7m
 Composition
varies

7. Number and Size of Peroxisomes
Vary Depending on Environment
Glucose limited More glucose limited Methanol limited
Hansenula polymorpha cells

8.  Peroxisomes are also called
Microbodies.
 Peroxisomes are about the
size of lysosomes (0.5–1.5
µm) and like them are bound
by a single membrane. They
also resemble lysosomes in
being filled with enzymes.

9.  They are round or oval vesicles surrounded by a
phosolipid bilayer
 Inside the vesicle are many, many enzymes
 Each peroxisome is a single membrane
 Each cell contains several hundred peroxisomes
 They resemble a lysosome but are not the same
 They are self replicating
 Size is variable, but it is roughly 700nm
 A peroxisome is found in the cytoplasm of a cell
 The organ that peroxisomes are most abundant in is
the liver
What they look like

10. 3-10
Peroxisomes
 Peroxisomes are vesicles than contain enzymes
to oxidize organic substances like fats. In other
words the use oxygen to break down molecules.
 The enzymes in these organelles produce
hydrogen peroxide
 Hydrogen peroxide is broken down right away by
the enzyme catalase into oxygen and water.
 Peroxisomes are abundant in the liver where
they produce bile salts and cholesterol and break
down fats.

11. 3.Location

12. Location

13. Inside the Cell
http://www.x-ald.nl/cell.jpg

14.  Peroxisome Place into Cytoplasm
 Each cell contain 100 or more than
peroxisome
 Present into both plant and animal
 Contain more than 50 Enzymes

15. 4.Origin

16. Origin
 Not well understood
 Endosymbiotic
 Some scientists believed that they come
from bacteria which are parasites
 Some other bilieved in Antibacterial origin

17. 5.Importance and Functions

18. Major Metabolic Functions of
the Peroxisome in Plants
1. -oxidation of fatty acids
2. Glyoxylate cycle
3. Photorespiration (Glycolate pathway)
4. Degradation of purines
5. Decomposition of hydrogen peroxide

19. Some of the functions of the
peroxisomes in the human liver:
 Breakdown (by oxidation) of excess fatty acids.
 Breakdown of hydrogen peroxide (H2O2), a potentially
dangerous product of fatty-acid oxidation. It is catalyzed
by the enzyme catalase.
 Participates in the synthesis of cholesterol.
 Participates in the synthesis of bile acids.
 Participates in the synthesis of the lipids used to make
myelin.
 Breakdown of excess purines (AMP, GMP) to uric acid.

20. Two Types of Peroxisomes in
Plants
 Leaves
 Catalyzes oxidation of side product of CO2
fixation in photorespiration
 Germinating seeds
 Converts fatty acid in seed lipids into sugars
needed for growth in the young plant

21. The Glycolate Cycle

22. Peroxide Detoxification
Oxidases use O2 to oxidize organic substances and
produce hydrogen peroxide (H2O2)
-- e.g., H2O2 generated by glycolate oxidase reaction,
-oxidation of fatty acids
Peroxisomes also contain catalase, the enzyme that
degrades H2O2.

23. Importance of H2O2 degradation
 2H2O2 2H2O + O2
 Peroxisomes contain a high concentration of
catalase, a heme protein
 Other reactive oxygen species (ROS) are
formed in peroxisomes
catalase
H - - O - - O - -H
HO- -OH (?)

24. Enzymatic pathways in
peroxisomes
 Fatty acid oxidation (VLCFA)
 H2O2 detoxification (catalase)
 Bile acid synthesis
 Plasmalogen synthesis
 Cholesterol synthesis
 Glyoxylate detoxification

25. 6.Peroxisomal Diseases

26. Peroxisomal Disorders
 16 disorders
 15 are autosomal recessive
 1 is X-linked (adrenoleukodystrophy)

27. Peroxisomal Diseases
Adrenoleukodystrophy: Deficiency in -oxidation of
very long-
chain fatty acids
Zellweger syndrome:
Defect in protein import,
giving rise to “ghost
peroxisomes”

28. Adrenoleukodystrophy/
Adrenomyeloneuropathy
 Most common peroxisomal disorder (1/20,000)
 ALD: progressive neurologic disorder that begins at 5-
12 years
 Boys with new onset school difficulties & ADHD
 Visuo-spatial deficits and hearing loss
 Spasticity, ataxia, maybe seizures
 Hypoglycemia, salt losing, hyperpigmentation

29. ZELLWEGER SYNDROME

30. Zellweger Syndrome

31. Zellweger Disorders
 Genetic heterogeneity
 Dysmorphism (large fontanelle, high forehead, abn ears,
micrognathia, low/broad nose, redundant skin folds)
 Neuronal migration disorders and delayed myelination
 Seizures
 Ocular abnormalities
 Liver disease
 Death in first year of life

32. 7.Conclusion

33. So Finally I conclude that the peroxisome is
the most Abundant Organelle which is maintaing and
controlling the cell functions like biogenesis of amino
acids,cholestorol,purine,plasmalogen etc.

34. Thank you !!!