Chloroplast

Plastics are an organelle found only in plant cells. There are 3 types of plastids: chromoplasts, chloroplast, and leucoplast. Chromoplasts are used for colour in flowers. l Leucoplasts are colourless, their main job is to store starch lipids and proteins. Chloroplast is the site of photosynthesis, it is green colour plastids. It contains a green coloured pigment called chlorophyll. Chloroplast is present in all green plants and algae. Plants produce their food by chloroplast. Chlorophyll can trap sunlight, which is necessary to produce food. Chloroplast contains a high amount of chlorophyll. Chloroplast is not present in animal cells. It is a membrane-bound organelle, It migrates and moves around plant cells.

Structure of chloroplast

The chloroplast is an oval-shaped organelle present in the mesophyll of the plant cells. There are different sizes of chloroplast present in algae. Sometimes there are too many 2 chloroplasts present in some algae, they can be star-shaped. The chloroplast has 3 membranes: the outer chloroplast membrane, and the thylakoid system.

Outer chloroplast membrane

It is a semipermeable membrane, small substances or ions can be transferred through it. It is not permeable to large molecules such as proteins. The polypeptides in chloroplast are synthesized in the cytoplasm, murder cell. The chloroplast form of stroma contains tubule, which is the result of protruding of chloroplast membrane into the cytoplasm.

Intermembrane space and peptidoglycan wall

The intermembrane space is about 10 to 20 nanometres. It lies between the outer and inner membrane.

Inner chloroplast membrane

This membrane controls the passage of substances into and out of the chloroplast. The substance must pass through the translocon, TIC Complex, being passed through the outer membrane. The other job of an inner membrane is the synthesis of lipids, proteins, and fatty acids.

Peripheral reticulum

The peripheral reticulum is present in some chloroplast. Generally, it is found in the chloroplasts of the C4 plants, sometimes in C3 and gymnosperms. The function of the peripheral reticulum is to increase the space of the chloroplast, it sometimes acts as a vehicle for transport.

Stroma

It is a protein-rich structure. It is an aqueous fluid, alkaline, present in between the inner membrane and thylakoid space. Many proteins float around it, such as DNA and ribosomes. Chloroplast contains its own ribosome.

Plastoglobuli

It is a spherical bubble-shaped made up of lipid and proteins, its size is 40 to 60 nanometres. It is present in all chloroplasts. Enzymes and structural proteins are present in plaster globally, which are responsible for the synthesis of lipids and the process of metabolism.

Starch granules

It is very common in chloroplasts, the 15% of organelle is the starch granules. They have no fixed composition and place.

Pyrenoids

It is present in higher plants, it is round and is a place of accumulation of starch.

The Thylakoid system

It is a small, connected SAC-like structure. The light reaction in photosynthesis takes place in the light system. The system is composed of grana and inter joined stroma thylakoids. Grana is a stack of lamellae. The light energy is converted into chemical energy in grana. 

The function of chloroplast

The main function of chloroplast is to perform photosynthesis in plants and algae. It converts light energy into chemical energy, which is why carbon dioxide and water are converted into sugar and oxygen.

It also helps in the Calvin cycle, it changes the inorganic carbon dioxide into organic molecules of carbohydrate. This process is also known as carbon dioxide fixation. The Calvin cycle is also called the dark reaction.

Chloroplast is necessary for the survival and growth of plants and algae.

Chloroplasts are also necessary for the immunity of plants. Chloroplast, cell membrane endoplasmic reticulum and nucleus are important for the defence of plants from pathogens.

Chloroplast stores hydrogen ions, which are used in the generation of ATP energy. They help in the process of photophosphorylation.

Chloroplast is also used in the reduction of NADP+. In the reduction of NADP, the removal of electrons occurs in the electron transport chain.

It also helps in cyclic photophosphorylation in which the recycling of electrons occurs. When the oxygen concentration is very high when the concentration of oxygen is very high photorespiration happens which happens in chloroplasts.

Conclusion 

The chloroplast is found in all green plants and photosynthesis algae. It performs the main part of plants, which is to make food. It is not present in some plants, which do not perform photosynthesis for synthesis. It is a round-shaped structure found scattered in plants to sell. It is a membrane-bound organelle. It contains chlorophyll which is a green colour pigment that saves the solar energy to make food, it also works as an immunity system for the plant. It has 3 membranes: outer membrane, thylakoid, and the outer chloroplast membrane.Chloroplast stores hydrogen ions, which are used in the generation of ATP energy. They help in the process of photophosphorylation .It also helps in cyclic photophosphorylation in which the recycling of electrons occurs. When the oxygen concentration is very high when the concentration of oxygen is very high photorespiration happens which happens in chloroplasts.