Why are glycolen and starch good storage materials?
Glycogen and starch are good storage materials for organisms because they both serve as long-term energy storage molecules.
To understand why they are effective for this purpose, let's break down their properties and how they are synthesized.
1. Glycogen:
Glycogen is a polysaccharide that is primarily found in animal cells. It is used by animals, including humans, to store glucose molecules for later use. Here's how glycogen serves as a good storage material:
a. Branched structure: Glycogen has a highly branched structure, meaning it has many side branches off the main chain. This branching allows for quick and efficient breakdown of glycogen to release glucose when the body needs energy. The branching prevents the entire molecule from being broken down at once, enabling a more controlled energy release.
b. Water solubility: Glycogen is water-soluble, making it easy to store and transport within cells. It can be rapidly broken down by enzymes called glycogen phosphorylase, releasing glucose molecules as an energy source.
c. Storage capacity: Glycogen can be stored in large quantities in the liver and muscle cells. This allows animals to store and access glucose for their energy needs during periods of fasting or intense physical activity.
2. Starch:
Starch is a polysaccharide that is primarily found in plant cells, serving as their principal energy storage molecule. Similar to glycogen, starch exhibits properties that make it an excellent storage material:
a. Alpha-glucose linkage: Starch is composed of glucose molecules linked together by alpha-glycosidic bonds. This type of linkage enables easy digestion by enzymes present in the digestive system of animals, including humans.
b. Granular structure: Starch is stored in the form of granules within plant cells, allowing for efficient packing and storage. These granules can be quickly broken down, facilitating the release of glucose monomers when needed.
c. Amylose and amylopectin: Starch consists of two main components: amylose and amylopectin. Amylose is a linear chain of glucose units, while amylopectin is highly branched, similar to glycogen. This combination of linear and branched structures enables easy breakdown and controlled release of glucose during digestion and metabolism.
In summary, glycogen and starch are good storage materials because of their ability to store glucose molecules efficiently, their water solubility, and their controlled release of energy. Their structures and properties allow organisms to store and access energy when needed, making them essential for survival.