This document discusses lysosomes and their role in intracellular digestion. It begins by introducing lysosomes and their structure, which contains hydrolytic enzymes. Lysosomes are formed from the Golgi apparatus and contain acid phosphatases within a single membrane sac. They function to digest macromolecules through autophagy and phagocytosis. Lysosomes maintain an acidic pH to activate their hydrolase enzymes and have transport proteins to export digestion products. Multiple pathways, including autophagy and endocytosis, deliver materials to lysosomes for breakdown. Some genetic diseases result from deficiencies of lysosomal enzymes, preventing breakdown of substances like glycogen.

2. ROLE OF
LYSOSOMES AS
HYDROLYTIC
ACTIVITY OF
ENZYMES
ROLE OF
LYSOSOMES AS
HYDROLYTIC
ACTIVITY OF
ENZYMES

3. Introduction of Lysosomes
Structure of Lysosomes
Formation of Primary Lysosomes
Formation of Secondary Lysosomes
Lysosomes are the principal sites of
intracellular digestion
Multiple Pathways Deliver Material to
Lysosomes
CONTENTS

4. Functions of Lysosomes
Steps in Autophagy
Storage Diseases

5.  cytoplasmic organelles
 Structure is different from other
organelles
 Isolated by Duve in 1949
Lyso soma
Splitting body
SO they are concerned with the breaking

6. ✿ Bounded by a single membrane.
This membrane forms a simple sac.
✿This sac contains several hydrolytic
enzymes like acid phosphatases.

7. Enzymes of lysosomes are
synthesized by ribosomes  present
in RER transferred to Golgi
apparatus
These enzymes are further
processed in the Golgi apparatus.
Budded off as Golgi vesicles
primary lysosomes.

8. Secondary lysosomes are formed by
two method
☞The foreign object
fuses with the
primary lysosomes to
form secondary
lysosomes.
☞In lysosomes
,enzymes digest the
food particles.
☞ (A) Lysosomes
protect the body
against the invading
organisms.
☞Engulf the food
particles.

9. • Some time, under some abnormal
conditions like starvation or normal
physiological conditions, the primary
lysosomes engulf the parts of cell.
• It digests these parts and release
energy.
• The lysosomes which eat parts of its
own cells are called autophagosomes.
• These autophagosomes are also
called secondary lysosomes

11. • Membrane-enclosed compartment filled
with soluble hydrolytic enzymes that
control intracellular digestion of
macromolecules.
• Containing about 40 types of hydrolytic
enzymes including
• Protease that digest proteins
• Nuclease that digest nucleic acids
Lysosomes are the intracellular Digestion

12. • Lipase that digest lipids
• Phospholipase that digest phospholipids
• All are hydrolases.
• For optimal activity, they need to be
activated by proteolytic cleavage and
require environment, which the lysosome
provides by maintaining an pH of about
4.5-5.0 in its interior .
• Contents of the cytosol are doubly
protected by the cell’s own digestive
system:

13. • The membrane of the lysosome
keeps the digestive enzymes out of
the cytosol, but even if they leak out,
they can do little damage at he
cytosolic pH about 7.2
• Like all other intracellular
organelles, the lysosome contains a
unique collection of enzymes, it also
has a unique surrounding
membrane.

15. • Most of the lysosomal membrane
proteins, for example, are unusually
highly glycosylated, which helps to
protect them from the lysosomal
proteases in the lumen.
• Transport proteins in the lysosomal
membrane carry the final products of
the digestion of macromolecules-such
as amino acids, sugars, and
nucleotides-to the cytosol, where the
cell can either reuse or excrete them.

16.  Auacuolar H⁺ ATPase in the
lysosomal membrane uses the energy
of ATP hydrolysis to pump H⁺ into the
lysosome, thereby maintaining the
lumen at its acidic pH
The lysosomeal H⁺ pump belongs to
the family of V-type ATPase

17. Multiple pathway to Deliver Materials to Lysosomes

19. • AUTO PHAGY:
• oneself to eat
• Autophagy is a process of self-eating and
self-degradation. The degradation takes part
when the cell content and organelles is
consumed by lysosomes
• Cell contains some old, broken parts like old
mitochondria.

20. • The cell produces vesicles called
autophagosomes that captures and deliver
cytoplasmic material to lysosomes.
The macromolecules taken up from
extracellular fluid by endocytosis.
endocytosed molecules are initially
delivered in vesicles to small, irregularly
shaped intracellular organelles called early
endosomes.

21. • Lysosomes then fuse with endosomes,
whereby it transfers it enzymes to
breakdown molecules. The broken down
molecules are then delivered to the
cytoplasm by proteins for later
consumption.
• Any foreign object is engulfed by
lysosomes
• Broken into digestive
pieces.phagocytosis
Phagocytosis

22. • Lysosomes contain enzymes which
can digest the phagocytosed food
• :
• Lysosomes also release enzymes for
extracellular digestion.

23. 1) Nucleation and extension of a
delimiting membrane into a crescent
shaped structure that engulfs a
portion of the cytoplasm.
2) Closure of the autophagosomes into
a sealed double- membrane –
bounded compartment
3) Fusion of the new compartment
with lysosomes

24. • Digestion of the inner membrane of the
autophagysome and its contents.

25. • Several congenital diseases are
caused accumulation of certain
substances like glycogen and
glycolipids.
These disease caused due to mutation.
Affects the lysosomal enzymes.
These diseases are caused due to
absence of certain enzymes.

26. ✿
✿ The enzymes which breaks the
glycogen into glucose is absent.
✿ So, glycogen is filled in the
membranous bound organelles of the
cell of the muscles and liver.
Glycogenesis Type II

27. ☞ The enzymes which is involved in
the catabolism of lipid is absent.
☞ Cause accumulation of lipids in
brain cells
☞ Cause mental retardation
☞ And even death.