Chloroplast
This article describes an organelle, a cell component with its own distinctive structure and function. In eukaryotic cells, this is bounded by its own membrane, which is a lipid bilayer made of phospholipid.
Unless otherwise specified, information about this organelle is about its in situ occurrence in vivo, i.e., its occurrence in its usual location in living cells.
Definition
Chloroplast is an organelle found in the plant cells that are part of green tissue (such as leaves) in most plants (i.e., the ones that are capable of photosynthesis). The chloroplast's main function is to carry out photosynthesis, using sunlight to convert atmospheric carbon dioxide and water into glucose and oxygen.
Summary
| Item | Value |
|---|---|
| Type of organisms whose cells contain chloroplasts | Most plants; the exceptions are plants incapable of carrying out photosynthesis (these plants are generally heterotrophic -- they rely on other plants for food, and known examples are all parasitic).[1][2] NOTE: Fungi, though plant-like, are heterotrophic and do not contain chloroplasts. |
| Type of cells within the organism that contain chloroplasts | Most cells in green tissue; in particular, this includes leaves and green stems. On the other hand, root cells do not contain chloroplasts; similarly, cells in wood are dead and don't have chloroplasts. Fruit and flower cells usually do not contain chloroplasts. Even within the leaves, the cells that are part of the veins do not contain chloroplasts. |
| Number of chloroplasts per cell | The number depends on the organism; it could vary from 1 to a few hundred. For typical large plants it ranges from 20 to a little over 100. |
| Shape | Chloroplasts come in various shapes, such as round, oval, or disk-shaped. In higher plants, chloroplasts tend to be disk-shaped. |
| Size | diameter,[3] width about half the diameter (about )[4] |
| Location within cell | Chloroplasts are found throughout the cell, and move freely within the cell. |
| Structural components | outer chloroplast envelope, intermembrane space of chloroplast, inner chloroplast envelope, thylakoid |
| Chemical constituents | Perhaps the most distinctive and relevant chemical constituents are chlorophyll a and chlorophyll b, that result in the distinctive green color of chloroplasts and also facilitate photosynthesis. |
