Question

Single membrane-bound organelles are
(a) Lysosome
(b) Sphaerosome
(c) Glyoxysome
(d) All of the above

Answer 1

Hint: These kinds of organelles are present only in eukaryotic cells, mitochondria and chloroplast are the only double membraned structures present in the eukaryotic cell.

Complete answer:
Lysosome: This is a single membrane-bound structure present commonly in all cells. These are spherical organelles that contain hydrolytic enzymes that can break down multiple biomolecules present in a cell. The pH inside a lysosome is between 4.5 and 5. This is the optimum pH at which hydrolytic enzymes work. The activity of the lysosome is analogous to the function of the stomach. The main function of the lysosome is waste disposal. Lysosome takes in materials from the cytoplasm that aren’t useful and digests them this is called autophagy.

Sphaerosomes: These are also called Oleosome, these are single membrane-bound organelles in the cells who participate in the synthesis of lipids. They are found in plant cells but are absent in animal cells. These arise from the endoplasmic reticulum, the membrane in these organelles is a monolayer, the hydrophobic tails are towards the inner side of the organelle and the hydrophilic heads are outside to the cytosol. spHerosomes are mainly made up of lipid (98%) and the rest is a protein content (2%) which are assumed to be enzymatic in action.

Glyoxysomes: They are found in plants and work like peroxisomes. They are generally found in fat storage tissues of seeds and in filamentous fungi. The function of this single membraned organelle is the storage of fats and oils, it is commonly found in corn, sunflower, peanuts, and pumpkin. These also contain enzymes that initiate the breakdown of fatty acids.

So, the correct answer is ‘All of the above’

Note: Apoptosis (programmed cell death) is caused by lysosome when the cell is malfunctioning or when the cell has aged. It is also known as the suicidal bag of the cell.