✦✦✦✦ LYSOSOMES ✦✦✦✦
DEFINITION;
➤LYSOSOMES ARE CYTOPLASMIC ORGANELLES AND ARE DIFFERENT FROM
OTHER DUE TO THEIR MORPHOLOGY.
DISCOVERED BY;
➤THESE WERE ISOLATED AS A SEPARATE COMPONENT FOR THE FIRST TIME
BY DE DUVE (1949).
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MEANINGS;
➤LYSOSOMES (LYSO=SPLITTING; SOMA=BODY) ARE FOUND IN MOST
EUKARYOTIC CELLS.
FUNCTION;
➤ANY FOREIGN OBJECT THAT GAINS ENTRY INTO THE CELL IS IMMEDIATELY
ENGULFED BY THE LYSOSOMES AND IS COMPLETELY BROKEN INTO
SIMPLE DIGESTIBLE PIECES.
THE PROCESS IS KNOWN AS PHAGOCYTOSIS ( EATING PROCESS OF A CELL).
MOSTLY FOUND;
➤THEY ARE MOST ABUNDANT IN THOSE ANIMAL CELLS WHICH EXHIBIT
PHAGOCYTIC ACTIVITY.
BOUNDED BY;
➤THEY ARE BOUNDED BY A SINGLE MEMBRANE AND ARE SIMPLE SACS
RICH IN ACID PHOSPHATASE AND SEVERAL OTHER HYDROLYTIC
ENZYMES. THESE ENZYMES ARE SYNTHESIZED ON RER AND ARE
FURTHER PROCESSED IN THE GOLGI APPARATUS.
AUTOPHAGOSOME; (AUTOPHAGY)
THE LYSOSOMES WHICH EAT PARTS OF THEIR OWN CELL ARE KNOWN AS
AUTOPHAGOSOME.
★ DURING THIS PROCESS SOME OLD, WORN OUT PARTS OF CELL, SUCH AS
OLD MITOCHONDRIA ARE DIGESTED.
RELEASE OF ENZYMES;
LYSOSOMES ALSO RELEASE ENZYMES FOR EXTRA CELLULAR DIGESTION.
CAUSE OF DISEASES;
SEVERAL CONGENITAL DISEASES HAVE BEEN FOUND TO BE DUE TO
ACCUMULATION WITHIN THE CELL OF SUBSTANCES SUCH AS GLYCOGEN
OR VARIOUS GLYCOLIPIDS.
★THEY ARE ALSO CALLED STORAGE DISEASES AND ARE PRODUCED BY
MUTATION THAT AFFECT ONE OF THE LYSOSOMAL ENZYMES INVOLVED
IN THE CATABOLISM OF A CERTAIN SUBSTANCE.
FOR EXAMPLE;
IN GLYCOGENESIS TYPE II DISEASE,
➡THE LIVER AND MUSCLE APPEAR FILLED WITH GLYCOGEN WITHIN
MEMBRANE BOUND ORGANELLES. IN THIS DISEASE, AN ENZYME
THAT DEGRADES GLYCOGEN TO GLUCOSE, IS ABSENT.
TAY-SACH'S DISEASE;
➡IT IS BECAUSE OF ABSENCE OF AN ENZYME THAT IS INVOLVED IN THE
CATABOLISM OF LIPIDS. ACCUMULATION OF LIPIDS IN BRAIN CELLS
LEAD TO MENTAL RETARDATION AND EVEN DEATH.
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