What is the difference between grana and granum?

"Grana" and "granum" are terms used to describe different aspects of the structure of chloroplasts in plant cells.

Grana (plural of granum): Grana are stacks of flattened, membranous sacs called thylakoids found within the chloroplasts of plant cells. These thylakoid stacks are interconnected and contain the photosynthetic pigments, including chlorophyll, which capture light energy and are essential for the process of photosynthesis. Grana play a crucial role in the light-dependent reactions of photosynthesis, where light energy is converted into chemical energy.

Granum (singular): Granum refers to a single stack of thylakoids within the chloroplast. Each granum contains multiple thylakoid discs, and the arrangement of thylakoids in granal stacks enhances the efficiency of light absorption and the subsequent reactions of photosynthesis.

In summary, "granum" refers to an individual stack of thylakoids, while "grana" is the plural form and refers to multiple stacks of thylakoids within a chloroplast. These structures are essential for the photosynthetic process in plants, as they provide a platform for the organization of photosynthetic pigments and the execution of light-dependent reactions.