2. History of Peroxisomes
• First observed by electron microscopy in
animal cells (1950), then in plant cells
(1960)
Christian deDuve (1965)
Isolated from liver cells by centrifugation
Called them peroxisomes because they
generate and destroy H2O2
3.
4.
5. 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.
6. What they look like
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
7. 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.
3-10
9. 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
10. 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 .
Breakdown of excess purines (AMP, GMP) to uric acid.
11. 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
14. 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, etc.
Conclusion
