MICROBODIES MCQ - Practice Questions with Answers

MICROBODIES

These are the small, single membrane-bound cell organelles that are involved in the absorption of molecular oxygen and oxidation. 

1. Peroxisomes:

• These microbodies contain enzymes for peroxide biosynthesis. 
• These are present in both the plant cells and animal cells in close proximity to ER, mitochondria and chloroplasts. 
• The following enzymes are present in the peroxisomes:

1.                  Urate oxidase
2.                  D-amino acid oxidase
3.                  Α-hydroxy acid oxidase
4.                  Β- hydroxy acid oxidase

• In the presence of molecular oxygen, hydrogen peroxide is formed which is metabolised by catalase enzyme.

Functions of Peroxisomes:

• Peroxisomes are mainly concerned with fatty acid metabolism.
• They carry out oxidation reactions that result in the formation of hydrogen peroxide. 
• This hydrogen peroxide is used to detoxify the toxic compounds. Peroxisomes in the liver help in detoxification of alcohol. 
• In plants, the peroxisomes play an important role in the mobilization of fatty acids during the seed germination. The fatty acids are converted to sugars which provide energy. 
• Peroxisomes also help to recycle phosphoglycolate - a by-product of the Calvin cycle. This is a very important function as if the recycling didn't happen a lot of the cell's energy and carbon would be lost.

2. Glyoxysomes:

• These are specialised single membrane-bound microbodies found in plants (Particularly in fat-storing tissues) and filamentous fungi. 
• The key enzymes of the glyoxylate cycle - isocitrate lyase and malate synthase are present in the glyoxysomes. 
• They are responsible for the breakdown of fatty acids and their conversion into sugars through gluconeogenesis. 
• They are believed to be special types of peroxisomes.