Chloroplast diagram class 9

The structure of the chloroplast In plants, photosynthesis takes place primarily in leaves, which consist of many layers of cells and have differentiated top and bottom sides. The process of photosynthesis occurs not on the surface layers of the leaf, but rather in a middle layer called the mesophyll ( Figure 1). Figure 1 Not all cells of a leaf carry out photosynthesis. Cells within the middle layer of a leaf have chloroplasts, which contain the photosynthetic apparatus. (credit The gas exchange of carbon dioxide and oxygen occurs through small, regulated openings called stomata. Figure 2 Tomato leaf stomate (singular of stomata). Photo credit: In eukaryotes, photosynthesis takes place inside an organelle called a chloroplast. Some prokaryotes can perform photosynthesis, but they do not contain chloroplasts (or other membrane-bound organelles). In plants, chloroplast-containing cells exist in the mesophyll. Chloroplasts are surrounded by a double membrane similar to the double membrane found within a mitochondrion. Within the chloroplast is a third membrane that forms stacked, disc-shaped structures called thylakoids. Embedded in the thylakoid membrane are molecules of chlorophyll, a pigment (a molecule that absorbs light) through which the entire process of photosynthesis begins. Chlorophyll is responsible for the green color of plants. The thylakoid membrane encloses an internal space called the thylakoid lumen or space. Other types of pigments are also involved in phot...

• Chloroplast is an organelle found in all photosynthetic cells of plants. • These are also found in some protists, for example, Euglena. • Chloroplasts are the most common type of plastid. • These are absent in those plants which are not exposed to light. • Chloroplast is derived from the Greek word “chloros”. It means green, and plastic, which means form. • Chloroplasts were first observed by Antony Von Leeuwehoek in 1679. • The term chloroplast was given by Schimper (1883 A.D.) • Chloroplast originated from proplastids found in the growing region of plants and are surrounded by two membranes. • When its size increases (up to 1µm) the inner membrane invaginates to form vesicles in the presence of sunlight. • They are very important for plants, because • In the cytoplasm of plant cells, the chloroplast is well distributed homogeneously. however, it is concentrated around the nucleus. • Similarly, in certain cells, it is present just beneath the plasma membrane. • They have a green color which helps to distinguish them from other types of plastid. The green color is produced from the presence of two pigments, chlorophyll a and chlorophyll b. • Other types of plastids such as leucoplast and the chromoplast do not carry out photosynthesis and have low concentrations of chlorophyll. • Other pigments, carotenoids are also present in chloroplast which serve as accessory pigments. Carotenoid trapping solar energy and passing it to chlorophyll. • Like mitochondria, chloroplast ha...

Term Meaning Photosynthesis The process by which plants, algae, and some bacteria convert light energy to chemical energy in the form of sugars Photoautotroph An organism that produces its own food using light energy (like plants) ATP Adenosine triphosphate, the primary energy carrier in living things Chloroplast The plant cell structure where photosynthesis occurs Thylakoids Disc-like structures within a chloroplast that help absorb light Grana Stacks of thylakoids in a chloroplast Chlorophyll A pigment found in the thylakoid that absorbs light energy and uses it to produce carbohydrates Stroma Fluid-filled space surrounding the grana On a simplified level, photosynthesis and cellular respiration are opposite reactions of each other. In photosynthesis, solar energy is harvested as chemical energy in a process that converts water and carbon dioxide to glucose. Oxygen is released as a byproduct. In cellular respiration, oxygen is used to break down glucose, releasing chemical energy and heat in the process. Carbon dioxide and water are products of this reaction. • Plants are green because chlorophyll reflects green light. Many people think that chlorophyll is green because it wants to absorb and use green light. However, this is not true. The color we see is actually the color of light that is being reflected. Therefore, chlorophyll reflects green light, while absorbing red and blue light. In an open environment, probably not by any noticeable amount. However, if you put th...