Question

Write an account of lysosomes and their role in cellular metabolism.

Answer 1

Lysosomes are specialized vesicles within cells that digest large molecules through the use of hydrolytic enzymes.They are tiny spheres with lipid bilayer surrounding them. The size of lysosome is 0.1 to 1 micrometer. They are formed by budding off of the Golgi apparatus, and the hydrolytic enzymes within them are formed in the endoplasmic reticulum. The enzymes are tagged with the molecule mannose-6-phosphate, transported to the Golgi apparatus in the form of vesicles, and then packaged into the lysosomes.There are many different types of enzymes in lysosomes which are named for the molecules they break down, for e.g. protease breaks down proteins, and nucleases break down nucleic acid.

The function of lysosomes:

1) Digestion of intracellular substances like mitochondria, ER by autophagy.

2) Removal of dead cells.eg.WBC with engulfed bacteria.

3) Metamorphosis in the animal like the disappearance of the tail from tadpole larva of a frog.

4) Help sperm to penetrate the vitelline layer of the ovum.

5) Autolysis of cartilage and bone tissue in presence of excessive vitamin A.

7) Mediates repair of the plasma membrane, cell homeostasis and energy metabolism.

8) Adaptation to environmental cues such as starvation.