Question

Pyrenoids are the centers for the formation of
a. Proteins
b. Enzymes
c. Fats
d. Starch

Answer 1

Hint: Pyrenoids are the sun-cellular microcompartments or simply the dense bodies present inside the chloroplast of certain algae and other plants. They consist of a central granular core which is proteinaceous and surrounded by a layer of starch cells. Pyrenoids are associated with the carbon concentrating mechanism.

Complete answer:
Pyrenoids are subcellular micro-compartments present in the chloroplast which were discovered first by Vaucher. He described it as the units which are responsible for the fixation of carbon dioxide. It helps in keeping the concentration of carbon dioxide around the photosynthetic enzymes. It is composed of biomolecules that have one or more amino acids and a polysaccharide.

These are unique to algae chloroplast which is responsible for polymerizing sugars to starch. This is the reason they act as starch reservoirs. Due to the deposition of starch, a layer of starch cells forms a sheath around it. The centers of Pyrenoids are proteinaceous and they are responsible for the formation of starch.

Hence, the correct answer is option (D).

Additional information:
• Proteins are synthesized in the ribosomes.
• Enzymes are synthesized in the stroma/ matrix of the thylakoid membrane.
•Fat synthesis occurs in the cytoplasm of the cell via the photosynthetic process.

Note: Many algae show pyrenoids as tiny spherical bodies located in the cytoplasm of the plant cell. The central protein mass is known as pyrene-crystal. Significant overlap is seen between algal species in the pyrenoid morphology and ultrastructure.
Also, the mechanism of pyrenoid’s carbon fixation is by the production of a carbon dioxide-rich environment and keeping it sustained around the enzyme 1,5 - bisphosphate carboxylase/ oxygenase RuBisCo photosynthetic enzyme.