Disaccharides

Disaccharides
Sucrose A crystalline disaccharide of fructose and glucose, C12H22O11, found in many plants but extracted as ordinary sugar mainly from sugarcane and sugar beets, widely used as a sweetener or preservative and in the manufacture of plastics and soaps, also called saccharose.
Sucrose is one of the main products of photosynthesis and the most common transport sugar in plants. It is also a no reducing disaccharide, and is synthesized in the cytosol via the phosphorylated intermediate, sucrose‐6′‐phosphate. In leaves, the rate of sucrose synthesis is tightly co‐ordinated with the rates of photosynthetic carbon dioxide fixation and starch synthesis in the chloroplasts. Sucrose is transported from leaves via the phloem, to provide the rest of the plant with carbon and energy for growth and storage product synthesis. Sucrose is also unloaded from the phloem in sink organs. It can be hydrolyzed by cell wall inverses and imported into the cells as hexose sugars, or taken up intact and metabolized by intracellular inverters or sucrose synthase
Lactose A sugar present in milk. It is a disaccharide containing glucose and galactose units. Lactose is milk sugar. It's not as sweet as table sugar, but like table sugar, lactose provides your cells with energy when you eat it. You can use lactose for a number of other purposes, all of which it has in common with other carbohydrates like table sugar and starch.
Because you can't absorb whole lactose, your cells can't use it. But they can use its component sugars, glucose and galactose. These give you a source of immediate energy, just as table sugar and starch do. Your cells can also convert the components of lactose into the storage carbohydrate glycogen, which provides a supply of sugar for periods of fasting, Drs. Reginald Garrett and Charles Grisham expalin in their book "Biochemistry." You can also convert the sugars into fat
Maltose A type of carbohydrate. Carbohydrates are one of the nutrients necessary for our body to properly function and are one of the main sources of energy for the body. They are typically composed of carbon, hydrogen, and oxygen. Maltose is made by combining two glucose units together. Glucose has six carbons, six oxygen, and twelve hydrogen. Maltose is a sweet carbohydrate. In comparison to other common sweet carbohydrates, such as sucrose (table sugar) and fructose, it is a lot less sweet. Due to its lack of sweetness, it isn't often added to products as a sweetener. It does come into use in the malting process of barley (in order to make beer)

Polysaccharides
Glycogen is the storage form of carbohydrates in mammals. In humans the majority of glycogen is stored in skeletal muscles (∼500 g) and the liver (∼100 g). Food is supplied in larger meals, but the blood glucose concentration has to be kept within narrow limits to survive and stay healthy.
A main function of glycogen is to maintain a physiological blood glucose concentration, but only liver glycogen directly contributes to release of glucose into the blood. Skeletal muscles are unable to release glucose (because muscles lack glucose 6-phosphatase) and muscles glycogen is mainly a local energy substrate for exercise, rather than an energy source to maintain blood glucose concentration during fasting. Indeed, muscle glycogen can be broken down to lactate, which can be transported to the liver and via gluconeogenesis in the liver contribute to maintaining euglycemia (Cori cycle).
Starch is the storage polysaccharides in plant. It is their reservoir of food. They store starch as starch granules. Starch has been identified as a major integrator in the regulation of plant growth to cope with continual changes in carbon availability. Its importance is demonstrated by the phenotype of starch-deficient mutants, which grow poorly or even die in short-day conditions In heterotrophic storage organs such as potato (Solanum tuberosum) tubers or developing seeds, starch serves as a longer term carbon store, which is remobilized later in development to support phases of reproductive growth. Since such supply to these tissues is fluctuating, regulatory mechanisms are required to stimulate starch synthesis when carbon availability increases
In addition to its central role in plant physiology, starch is also of great economical importance. It is the second most abundant biopolymer on earth, after cellulose, and the most important carbohydrate used for food and feed purposes. Therefore, it represents the major resource of our diet and feedstock for many industrial applications, including bioethanol production. Understanding starch biosynthesis in plants could pave the way to new strategies to improve crop yield via the use of reverse genetics or marker-assisted breeding.
Cellulose is a polysaccharide (a form of carbohydrate) that has a structural role in animals and plants. In plants, cellulose is the compound that gives rigidity to the cells.
Because there are so many plants in the world (think of all the flowers, trees, weeds, grasses, vines, and bushes), cellulose, which is found in every cell of every plant, is the most abundant organic compound on earth. Most animals can’t digest cellulose because it is so hard to break down. Animals that eat only plants (herbivores) have special sacs in their digestive system to help break down cellulose. Humans can’t digest cellulose either. (The proof is in the toilet the day after you eat corn, for example.) Because cellulose passes through your digestive tract virtually untouched, it helps maintain the health of your intestines. One way cellulose helps the intestines is that it clears materials from the intestinal walls, keeping them clear, which may help to prevent colon cancer. Cellulose is the fiber (or roughage) of which your cereal box says you need more
Chitin is the second most abundant biopolymer in nature, where it protects crustaceans, parasites, fungi, and other pathogens from the adverse effects of their environments, hosts, or both. It is a glucose-based unbranched polysaccharide widely distributed in nature as the principal component of exoskeletons of crustaceans and insects as well as of cell walls of some bacteria and fungi.
Chitin is the most abundant renewable polymer in the oceans and is an important source of carbon and nitrogen for marine organisms. The process of chitin degradation is a key step in the cycling of nutrients in the oceans and chitinolytic bacteria play a significant role in this process. These bacteria are autochthonous to both marine and freshwater ecosystems and produce chitinases that degrade chitin, an insoluble polysaccharide, to a biologically useful form. In this brief review, a description of the structure of chitin and diversity of chitinolytic bacteria in the oceans is provided, in the context of the significance of chitin degradation for marine life