chloroplast diagram - Biology Junction

Plants cells contain a number of structures that are involved in the process of photosynthesis:

Diagram of chloroplast and its parts

The light-independant reactions of photosynthesis occur in the stroma of the chloroplast and involve the conversion of carbon dioxide and other compounds into glucose. The light-independent reactions can be split into three stages, these are carbon fixation, the reduction reactions and finally the regeneration of ribulose bisphosphate. Collectively these stages are known as the Calvin Cycle.

Chloroplasts are the site of photosynthesis in eukaryotic cells.

During carbon fixation, carbon dioxide in the stroma (which enters the chloroplast by diffusion) reacts with a five-carbon sugar called ribulose bisphosphate (RuBP) to form a six-carbon compound. This reaction is catalysed by an enzyme called ribulose bisphosphate carboxylase (large amounts present within the stroma), otherwise known as rubisco. As soon as the six-carbon compound is formed, it splits to form two molecules of glycerate 3-phosphate. Glycerate 3-phosphate is then used in the reduction reactions.

During this process of food generation, the following reaction takes place:





According to the diagram of photosynthesis, the process begins with three most important non-living elements: water, soil, and carbon dioxide.


Chloroplasts The sketch of the ..

The stacks of thylakoids are called grana. They are connected with an extensive sytem of tubules. The thylakoid membranes contain chlorophyll and other arranged in to capture light energy for two photosystems called and . In most plants, both photosystems are used in an that yields energy in the form of and to the stroma of the chloroplast to be used in the synthesis of carbohydrates. The energy is used in the to fix carbon from atmospheric CO2 and construct sugars.

Chloroplasts belong to a class of organelles known as plastids

The sketch of the chloroplast above was made from an electron micrograph of a chloroplast from a higher order plant (Levy). Plants use energy from the sun in tiny energy factories called chloroplasts. Using in the process called , they convert the sun's energy into storable form in ordered molecules such as . In this way, carbon dioxide from the air and water from the soil in a more disordered state are combined to form the more ordered sugar molecules.

What is the function of chloroplasts

Plants use energy from the sun in tiny energy factories called . The green color of leaves is attributable largely to these chloroplasts because they contain for . Though obviously oversimplified, the illustration depicts the somewhat elongated sausage type shape with large dimension 5-10 μm and smaller dimension 3-4 μm. Moore suggests 40-200 chloroplasts per photosynthetic cell and about 500,000 per square millimeter of leaf area.