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Starch (a polymer of glucose) is used as a storage polysaccharide in plants, being found in the form of both amylose and the branched amylopectin. In animals, the structurally similar glucose polymer is the more densely branched glycogen, sometimes called "animal starch". Glycogen's properties allow it to be metabolized more quickly, which ...
Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight. [4] Glycogen, the energy reserve of animals, is a more highly branched version of amylopectin. In industry, starch is often converted into sugars, for example by malting.
To generate energy, the plant hydrolyzes the starch, releasing the glucose subunits. Humans and other animals that eat plant foods also use amylase, an enzyme that assists in breaking down amylopectin, to initiate the hydrolysis of starch. [3] Starch is made of about 70–80% amylopectin by weight, though it varies depending on the source.
Amylose is important in plant energy storage. It is less readily digested than amylopectin; however, because of its helical structure, it takes up less space than amylopectin. As a result, it is the preferred starch for storage in plants. It makes up about 30% of the stored starch in plants, though the percentage varies by species and variety. [13]
Starch synthesis and storage also takes place in chloroplasts, a type of pigmented plastid involved in photosynthesis. [1] Amyloplasts and chloroplasts are closely related, and amyloplasts can turn into chloroplasts; this is for instance observed when potato tubers are exposed to light and turn green.
Structure of a plant cell. Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae.Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or ...
In many animals, including humans, this storage form is glycogen, especially in liver and muscle cells. In plants, starch is used for the same purpose. The most abundant carbohydrate, cellulose, is a structural component of the cell wall of plants and many forms of algae. Ribose is a component of RNA. Deoxyribose is a component of DNA.
Starch is stored in the amyloplasts, a specialized organelle found within plant cells, as starch grains. [4] The starch grain is specifically important for study due to the fact that it is commonly found in most plants, its long-lasting nature, as well as the diverse forms and structures that they can take based on which taxa they belong to. [4]