LYSOSOME AND MITOCHONDRIA

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AMIT KUMAR

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Lysosomes are spherical organelles that contain enzymes (acid hydrolases). They break up food so it is easier to digest. They are found in animal cells, while in yeast and plants the same roles are performed by lytic vacuoles.

The size of lysosome varies from 0.1–1.2 μm

Some important enzymes found within lysosomes include:

Lipase, which digests lipids Amylase, which digest carbohydrates (e.g.,

sugars) Proteases, which digest proteins Nucleases, which digest nucleic acids phosphoric acid monoesters.

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All these hydrolytic enzymes are produced in the endoplasmic reticulum, and to some extent in cytoplasm are transported and processed through the Golgi apparatus.

and through golgi apparatus they pinch off as single membrane vesicles.

Lysosomes are common in animal cells but rare in plant cells contain hydrolytic enzymes necessary for intracellular digestion

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It is called

"The Police Force of the Cell"

"suicide bags“

Lysosomes are produced in the Golgi Apparatus

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Lysosomes are sometimes called "suicide bags“

A lysosome is a membrane bag containing digestive enzymes

to digest food, the lysosome membrane fuses with the membrane of a food vacuole and squirts the enzymes inside.

The digested food can then diffuse through the vacuole membrane and enter the cell to be used for energy or growth.

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Mitochondria

EndosymbiosisMitochondria formed as a result of an endosymbiotic event around 2 billion years ago.

Mitochondrial compartmentsInner membrane•Respiratory chain and ATP synthase•impermeable to most charged molecules•highly folded into invaginations called cristae.

Outer membrane •Permeable to larger molecules

Matrix •Enzymes of the citric acid cycle, mtDNA

Intermembrane space •space between inner and outer membranes

Mitochondrial compartments

Mitochondrial energy productionThree major steps in oxidative phosphorylation

1) Production of reducing equivalents (NADH, FADH2) from glycolysis, fatty acid oxidation, and the citric acid cycle

2) Electron transport and generation of proton motive force

3) Phosphorylation - Synthesis of ATP, driven by the proton motive force

Mitochondria make other products

Mitochondria produce biosynthetic precursors

OXPHOS also leads to the production of:

•Superoxide: formed when O2 steals electrons from the ETC complexes

•Heat: a by-product of the reactions of OXPHOS

Mitochondrial reticulum

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