Question

Chloroplast are energy conveters .explain the the statement .draw its diagram and label it

Answer 1

Chloroplasts are a type of Plastids present in the Plant Cell and are green in colour. Chloroplasts contain a pigment called Chlorophyll, which gives the green colour to Chloroplast.

Chlorophyll is the only pigment in the world that helps a living thing to produce their own food. Chlorophyll is one the main internal sunstances that is used to convert Carbon Dioxide and Water to form Glucose and ATP. Chlorophyll is the pigment which takes place in presence of Sunlight, so photosynthesis is called Light Reaction. Another, part in Chloroplast is responsible for a reaction called Dark Reaction which is also a energy producing reaction. So, we can conclude that Chloroplasts are energy converters.

Answer 2

Chloroplast, structure within the cells of plants and green algae that is the site of photosynthesis, the process by which light energy is converted to chemical energy, resulting in the production of oxygenand energy-rich organic compounds. Photosynthetic cyanobacteria are free-living close relatives of chloroplasts; endosymbiotic theory posits that chloroplasts and mitochondria (energy-producing organelles in eukaryotic cells) are descended from such organisms.



chloroplast structureThe internal (thylakoid) membrane vesicles are organized into stacks, which reside in a matrix known as the stroma. All the chlorophyll in the chloroplast is contained in the membranes of the thylakoid vesicles.Encyclopædia Britannica, Inc.

Characteristics of chloroplasts

Chloroplasts are a type of plastid—a round, oval, or disk-shaped body that is involved in the synthesis and storage of foodstuffs. Chloroplasts are distinguished from other types of plastids by their green colour, which results from the presence of two pigments, chlorophyll a and chlorophyll b. A function of those pigments is to absorb light energy. In plants, chloroplasts occur in all green tissues, though they are concentrated particularly in the parenchyma cells of the leafmesophyll.



chloroplast; photosynthesisChloroplasts play a key role in the process of photosynthesis.Encyclopædia Britannica, Inc.

Chloroplasts are roughly 1–2 μm (1 μm = 0.001 mm) thick and 5–7 μm in diameter. They are enclosed in a chloroplast envelope, which consists of a double membrane with outer and inner layers, between which is a gap called the intermembrane space. A third, internal membrane, extensively folded and characterized by the presence of closed disks (or thylakoids), is known as the thylakoid membrane. In most higher plants, the thylakoids are arranged in tight stacks called grana (singular granum). Grana are connected by stromal lamellae, extensions that run from one granum, through the stroma, into a neighbouring granum. The thylakoid membrane envelops a central aqueous region known as the thylakoid lumen. The space between the inner membrane and the thylakoid membrane is filled with stroma, a matrix containing dissolved enzymes, starch granules, and copies of the chloroplast genome.



Chloroplasts circulate within plant cells. The green coloration comes from chlorophyll concentrated in the grana of chloroplasts.Encyclopædia Britannica, Inc.

The photosynthetic machinery

The thylakoid membrane houses chlorophylls and different proteincomplexes, including photosystem I, photosystem II, and ATP (adenosine triphosphate) synthase, which are specialized for light-dependent photosynthesis. When sunlightstrikes the thylakoids, the light energy excites chlorophyll pigments, causing them to give up electrons. The electrons then enter the electron transport chain, a series of reactions that ultimately drives the phosphorylation of adenosine diphosphate (ADP) to the energy-rich storage compound ATP. Electron transport also results in the production of the reducing agent nicotinamide adenine dinucleotide phosphate (NADPH).



chemiosmosis in chloroplastsChemiosmosis in chloroplasts that results in the donation of a proton for the production of adenosine triphosphate (ATP) in plants.Encyclopædia Britannica, Inc.

ATP and NADPH are used in the light-independent reactions (dark reactions) of photosynthesis, in which carbon dioxide and water are assimilated into organic compounds. The light-independent reactions of photosynthesis are carried out in the chloroplast stroma, which contains the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). Rubisco catalyzes the first step of carbon fixation in the Calvin cycle (also called Calvin-Benson cycle), the primary pathway of carbon transport in plants. Among so-called C4 plants, the initial carbon fixation step and the Calvin cycle are separated spatially—carbon fixation occurs via phosphoenolpyruvate (PEP) carboxylation in chloroplasts located in the mesophyll, while malate, the four-carbon product of that process, is transported to chloroplasts in bundle-sheath cells, where the Calvin cycle is carried out. C4 photosynthesis attempts to minimize the loss of carbon dioxide to photorespiration. In plants that use crassulacean acid metabolism(CAM), PEP carboxylation and the Calvin cycle are separated temporally in chloroplasts, the former taking place at night and the latter during the day. The CAM pathway allows plants to carry out photosynthesis with minimal .