Presented by

Surya Pratap Singh

M.Sc. Life Sciences

Central University of Gujarat

INTRODUCTION

• Lysosomes discovered by the cytologist Christian de Duve in the 1960.

• Lysosomes are spherical organelles thatcontain enzymes . They break up food so it iseasier to digest. They are found in animalcells, while in yeast and plants .

• Lysosomes are common in animal cells butrare in plant cells contain hydrolytic enzymesnecessary for intracellular digestion.

STRUCTURES OF LYSOSOME

• Lysosomes are spherical structures bounded by a

single unit membrane.

• The size of lysosomes varies from 0.2 to 0.8 nm.

• lysosomal membranes are sensitive to many

labilizers and stabilizers

ENZYMES OF LYSOSOMES

• Lysosomes are membrane enclosed

compartments filled with soluble hydrolytic

enzymes.

• Lysosomes contain about 40 types of

hydrolytic enzymes, including proteases,

nucleases, glycosidases, lipases,

phospolipases, phosphatases, and sulfatases.

• Lysosome provides by maintanining a pH

about 4.5 to 5.0.

LYSOSOMES ARE HETROGENEOUS

• The hetrogeneity of lysosomal morphologycontrasts with realatively uniform structuresof most other cell organelles.

• The late endosomes contain materialreceived from both the plasma membrane byendocytosis and newly synthesizedlysosomal hydrolases.

• Late endosomes fuse with preexistinglysosomes to form structures thatendolysosomes.

• Endolysosomes fuse and form lysosomes.

• This reason lysosomes are sometimes

view as a hetrogeneous.

PLANT AND FUNGAL VACUOLES ARE SIMILAR TO

LYSOSOMES

• Plant and fungal cells contain one or several very

large fluid-filled vesicles called vacuoles.

• It is related to animal cell lysosomes and

contain a variety of hydrolytic enzymes.

• The plant vacuole can act as a storage organelle

for both nutrients and waste products.

• The vacuole is important as a homeostatic

device.

• All these hydrolytic enzymes are produced

in the endoplasmic reticulum, and to some

extent in cytoplasm are transported and

processed through the Golgi apparatus.

• Lysosomal enzymes are synthesized in the

cytosol and the endoplasmic reticulum,

where they receive a mannose-6-phosphate

tag that targets them for the lysosome.

• If the lysosomal enzymes do not reach the

target it causes inclusion-cell disease,

resulting in accumulation of waste within

these organelles

THE FUNCTION OF LYSOSOMES

• A lysosome is a membrane bag containing

digestive enzymes.

• For 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.

• Lysosomes are sometimes called "suicide bags’’

• Lysosomes are the cells' garbage disposalsystem. They are used for the digestion ofmacromolecules from phagocytosis.

• Lysosome's pick up foreign invaders suchas bacteria, food and old organelles andbreak them into small pieces that canhopefully be used again.

• Autophagy may also lead to autophagiccell death, a form of programmed self-destruction, or autolysis of the cell, whichmeans that the cell is digesting itself.

CONCLUSION

• Lysosmes are specialized for the intracellular

digestion of macromolecules.

• These enzymes work only at low pH (highly

acidic) levels.

• Uncontrolled release of lysosome contents into the

cytoplasm can also cause cell death (necrosis).