Grana vs. Stroma

Main Difference

The main difference between Grana and Stroma is that grana are a membranous stacks structure within the chloroplasts of green algae and plants that comprises the chlorophyll and the site of the light reactions of photosynthesis. Whereas stroma is the supportive tissue of an epithelial organ, tumors, gonad, etc., comprising of blood vessels and connective tissues.

Difference Between Grana and Stroma

Comparison Chart

Grana vs. Stroma

Grana and Stroma are two unique structures of chloroplasts. Grana is the disk-like plates whereas stroma is the consistent, jell-like matrix of the chloroplast. Grana denotes to the stacks of thylakoids embedding in the stroma of a chloroplast while stroma refers to the neutral fluid adjacent the grana within the chloroplast. Grana present in the stroma but stroma present within the inner membrane of the chloroplast. Grana contains enzymes needs for the reliant reaction of the photosynthesis and ATP synthase enzymes requirements for making ATP molecules by chemiosmosis whereas stroma contains enzymes needs for the light-independent reaction of photosynthesis. Grana consist of different pigments such as chlorophyll-b, chlorophyll-a, carotene, and xanthophyll whereas stroma contains enzymes requires for photosynthesis, cytochrome system, DNA, and RNA of the chloroplast. The light reaction of photosynthesis arises in the grana whereas the dark reaction of the photosynthesis happens in the stroma. Grana deliver a large surface for the attachment of photosynthetic pigments whereas stroma embeds enzymes require by the dark reaction of photosynthesis.

What is Grana?

Grana denotes to the stacks of thylakoids embedding in the stroma of a chloroplast. A mixture of 2 to 100 thylakoids may form a granum. Each granum consists of 5-25 disc-shape thylakoids stacks one on the other like a stack of coins. A single chloroplast may comprise 10 to 100 grana. Thylakoids are also known as granum lamellae, which surrounds a space known as a locus. Grana are connecting by stromal thylakoids, but some of the thylakoids of a granum are connecting with thylakoids of another granum by a thin membrane known as stroma lamellae. Stromal thylakoids are also known as intergranal thylakoids. Both thylakoid and stromal thylakoid hold photosynthetic pigments on their surfaces. The light reaction of photosynthesis occurs on the surface of grana. Grana consist of different pigments such as chlorophyll-a, carotene, chlorophyll-b, and xanthophyll. Thylakoid is a round pillow-shape stack inside the chloroplast. The space between thylakoid membranes is known as the thylakoid lumen. The ATP synthase enzymes assign to granal layers help to synthesize ATP molecules by chemiosmosis. All grana in a particular chloroplast may perform as a single functional unit. Grana provide a large surface for the connection of Chlorophylls, electron carriers, other photosynthetic pigments and enzymes to perform light-dependent reaction of the photosynthesis. The photosynthetic pigments are attaches to a network of proteins in a very accurate manner forming photosystems, which allow the maximum light absorption.

What is Stroma?

Stroma denotes to a colorless jell-like surrounding substance of the chloroplast in which the dark reaction of photosynthesis takes place. Also, it also explains the stroma as a fluid-fill surrounding substance within the inner membrane of the chloroplast. The fluid is a colorless hydrophilic matrix housing DNA, oil droplets ribosomes, enzymes, and starch grains. Stroma consists of enzymes involve for photosynthesis, cytochrome system, DNA, and RNA of the chloroplast. Enzymes require the dark reaction which is embedding in the stroma. Stroma surrounds the grana. The light-independent period of photosynthesis takes place in the stroma. In the stroma, water and carbon dioxide are using in the production of simple carbohydrates by using the light energy trapping by the light reaction. As grana are surrounding by the stromal fluid so that products of the light-dependent reaction can rapidly pass into the stroma by granal membranes. The dark reaction of photosynthesis occur in stroma is known as the Calvin cycle. Three stages of the Calvin cycle are reduction reactions, carbon fixation, and RuBP regeneration.

Conclusion

Above this discussion, it concludes that Grana and stroma are two structures of the chloroplast. Grana are the stacks of thylakoids where the light reaction of photosynthesis takes place whereas stroma is the jelly-like matrix of the chloroplast, which contains the enzymes for the dark reaction of photosynthesis.