Question

The cell organelle bound by single unit membrane, which was first reported by Rhodin is involved in which of the following reaction?

• A. Conversion of glycine to serine
• B. Conversion of glyceride to PGA
• C. Formation of glycolate from phosphoglyeolate
• D. Conversion of serine to hydropyruvate

Answer 1

The correct option is D Conversion of serine to hydropyruvate

The cell organelle bound by a single unit membrane, which was first reported by Rhodin is Peroxisome. The peroxisome is involved in photorespiration. It is a process in C3 plants in which when there is high O${}_2$ concentration and temperature, O${}_2$ binds with RuBisCO instead of CO${}_2$ and form one molecule of phosphoglycerate and phosphoglycolate. The process consists of following steps:

1. Oxygen binds with RuBP oxygenase to form phosphoglycolate in chloroplast which gets converted to glycolate and transported to peroxisomes.

2. In peroxisomes, it forms glyoxylate and then glycine.

3. Glycine then enters mitochondrion and loses NH${}_4$ and CO${}_2$ in a reaction and it forms serine.

4. Serine is transported to peroxisomes and is converted to Hydroxy pyruvate or hydro pyruvate which is further converted to PGA and RuBP in the chloroplast.

Hence, in peroxisomes, 'conversion of serine to hydro pyruvate' occurs.