1
Literally mean

Lysosome (derived from the Greek
words lysis, meaning "to loosen", and soma,
"body“)
2
DISCOVERY
Christian de Duve, then chairman of the Laboratory of Physiological
Chemistry at the Catholic University of Louvain in Belgium, had been
studying the mechanism of action of a pancreatic hormone insulin in
liver cells.
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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.
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
The size of lysosomes varies from 0.1–1.2
μm.
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
Lysosomes are common in animal cells
but rare in plant cells contain hydrolytic
enzymes necessary for intracellular
digestion.
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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.

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
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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12

Lysosomes are the cells' garbage disposal
system. They are used for the digestion of
macromolecules from phagocytosis
(ingestion of other dying cells or larger
extracellular material, like foreign invading
microbes) .
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
endocytosis (where receptor proteins are
recycled from the cell surface), and
autophagy (wherein old or unneeded
organelles or proteins, or microbes that
have invaded the cytoplasm are delivered
to the lysosome). Autophagy may also
lead to autophagic cell death, a form of
programmed self-destruction,
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
Autophagy may also lead to autophagic
cell death, a form of programmed selfdestruction, or autolysis, of the cell, which
means that the cell is digesting itself.
15

Lysosomes pick up foreign invaders such
as bacteria, food and old organelles and
break them into small pieces that can
hopefully be used again.
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17

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.
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
The only thing that keeps the cell itself
from being digested is the membrane
surrounding the lysosomes.
19

These enzymes work only at low pH
(highly acidic) levels.

However because they can only work at
low pH levels and the rest of the cell has
a neutral pH level, they can be neutralized
if they accidentally escape from the
lysosome
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
In white blood cells that eat bacteria,
lysosome contents are carefully released
into the vacuole around the bacteria and
serve to kill and digest those bacteria.
Uncontrolled release of lysosome
contents into the cytoplasm can also
cause cell death (necrosis).
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CONCLUSION
In conclusion we see that the lysosomes
are a important factor to maintain the
‘cellular digestion’ in order.

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