explan the chloroplast with diagram
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Explanation:
Structure of Chloroplast
Chloroplasts are found in all higher plants. It is oval or biconvex, found within the mesophyll of the plant cell. The size of the chloroplast usually varies between 4-6 µm in diameter and 1-3 µm in thickness. They are double-membrane organelle with the presence of outer, inner and intermembrane space. There are two distinct regions present inside a chloroplast known as the grana and stroma.
Grana are made up of stacks of disc-shaped structures known as thylakoids. The grana of the chloroplast consists of chlorophyll pigments and are the functional units of chloroplasts.
Stroma is the homogenous matrix which contains grana and is similar to the cytoplasm in cells in which all the organelles are embedded. Stroma also contains various enzymes, DNA, ribosomes, and other substances. Stroma lamellae function by connecting the stacks of thylakoid sacs.
The chloroplast structure consists of the following parts:
Membrane Envelope
It comprises inner and outer lipid bilayer membranes. The inner membrane separates the stroma from the intermembrane space.
Intermembrane Space
The space between inner and outer membranes.
Thylakoid System
The system is suspended in the stroma. It is a collection of membranous sacs called thylakoids. The green coloured pigments called chlorophyll are found in the thylakoid membranes. It is the sight for the process of light-dependent reactions of the photosynthesis process. The thylakoids are arranged in stacks known as grana and each granum contains around 10-20 thylakoids.
Stroma
It is a colourless, alkaline, aqueous, protein-rich fluid present within the inner membrane of the chloroplast present surrounding the grana.
Grana
These are the sites of conversion of light energy into chemical energy.
Chlorophyll
It is a green photosynthetic pigment that helps in the process of photosynthesis.
Also read: Light-dependent Reactions
Functions of Chloroplast
Following are the important chloroplast function:
The most important function of the chloroplast is to synthesize food by the process of photosynthesis.
Absorbs light energy and converts it into chemical energy.
Chloroplast has a structure called chlorophyll which functions by trapping the solar energy and used for the synthesis of food in all green plants.
Produces NADPH and molecular oxygen (O2) by photolysis of water.
Produces ATP – Adenosine triphosphate by the process of photosynthesis.
The carbon dioxide (CO2) obtained from the air is used to generate carbon and sugar during the Calvin Cycle or dark reaction of photosynthesis
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