Question

pH of lysosome interior is
A. 10-12
B. 8-10
C. 5-7
D. 4-5

Answer 1

Lysosomes are electron microscopic membrane-bound vesicular structures of the cytoplasm that are involved in the intracellular digestive activities. These were first discovered by Christian de Duve in the liver cells.

Complete Answer:
Lysosomes are absent in prokaryotic cells but are present in all eukaryotic animal cells, some fungi, some protists and meristematic cells.

These are generally spherical in shape. They are formed of two parts:
(I) Limiting membrane- It is a single layered outer membrane that keeps a limit on digestive enzymes
(II) Matrix- It is an inner, finely granular and highly heterogeneous ground substance present inside the membrane.
- These are more in numbers in those cells that are involved in intracellular digestive activities, e.g. WBCs of blood, histiocytes of connective tissue, phagocytes, osteoclasts, etc.
- The matrix of lysosomes contain acid hydrolases and several other digestive enzymes like proteases, nucleases, glycosidase, phosphatases, esterase, etc. that digest cell organelles, engulfed pathogens, macromolecules, food particles, etc. The pH of lysosomes is slightly acidic and ranges from 4-5.
- Primary function of the lysosome is intracellular digestion of all the categories of macromolecules. It involves the digestion of exogenous materials of high molecular weight inside the cell. It can also initiate cell division by digesting repressor molecules.
- Lysosomes of osteoclasts digest the cartilage during the replacement of bones.
- Lysosomal enzymes of seeds help in digestion of proteins and starch for germination.

Hence the correct answer is option D.

Note: Lysosomes are also called suicidal bags or atom bombs because they cause autolysis. It involves the self-digestion of cells by lysosomal enzymes that are released after cell death.