Peroxisome

Peroxisomes

Submitted By,

Raghu Solanki

CUG/2014/1069

Life Science

CUG

Peroxisome

1. History

2. Introduction

3. Location

4. Origin

5. Importance and Functions

6. Disease

7. Conclusion

1.History

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

2.Introduction

The Peroxisome

Single membrane

Roughly

spherical

0.2 - 1.7m

Composition varies

Number and Size of Peroxisomes

Vary Depending on Environment

Glucose limited More glucose limited Methanol limited

Hansenula polymorpha cells

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.

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

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.

3.Location

Location

Inside the Cell

http://www.x-ald.nl/cell.jpg

Peroxisome Place into Cytoplasm

Each cell contain 100 or more than peroxisome

Present into both plant and animal

Contain more than 50 Enzymes

4.Origin

Origin

Not well understood

Endosymbiotic

Some scientists believed that they come from bacteria which are parasites

Some other bilieved in Antibacterial origin

5.Importance and Functions

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

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.

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

The Glycolate Cycle

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.

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 (?)

Enzymatic pathways in peroxisomes

Fatty acid oxidation (VLCFA)

H2O2 detoxification (catalase)

Bile acid synthesis

Plasmalogen synthesis

Cholesterol synthesis

Glyoxylate detoxification

6.Peroxisomal Diseases

Peroxisomal Disorders

16 disorders

15 are autosomal recessive

1 is X-linked (adrenoleukodystrophy)

Peroxisomal Diseases

Adrenoleukodystrophy: Deficiency in -oxidation of very long- chain fatty acids

Zellweger syndrome: Defect in protein import, giving rise to “ghost peroxisomes”

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

ZELLWEGER SYNDROME

Zellweger Syndrome

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

7.Conclusion

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.

Thank you !!!