Understanding Carbohydrates

is the base molecular formula for carbohydrates. Carbohydrates vary based on multiples of this formula (i.e. is the formula for glucose).

Carbohydrates and proteins are polymers (a long chain molecule generally composed of repeating single units), but glucose and lipids are not polymers (though glucose has the ability to polymerize). Proteins are polymers of amino acids. Carbohydrates are polymers of sugar monomers or monosaccharides. Lactose is a disaccharide or two sugar monomers connected.

The polysaccharide cellulose is a major component of plant cell walls. Similar to starch, cellulose is made up of glucose though the linkages in the polymers are different.

Energy is stored in the form of glucose. Cells, in turn, tap into glucose reserves to fuel cellular respiration. The carbon in glucose also serves as raw materials for the synthesis of other molecules such as amino acids.

Carbohydrates are polymers formed from simple sugars. Amino acids form proteins. Lipids are another class of subunits that make up fats.

The pancreas secretes glucagon to stimulate the breakdown of glycogen; insulin is secreted to stimulate its assembly in liver and muscle. Glycogen is, in fact, a polysaccharide. However, it is made up of glucose not fructose. Finally, plant cell walls contain cellulose. While similar to glycogen, cellulose is made of beta glucose linkages instead of alpha glucose linkages, causing cellulose to be a more linear polysaccharide while glycogen contains curving branches.

Starch is a polysaccharide stored in plants. Glycogen is a polymer of glucose in animals stored in the liver and muscle cells. Lipids are molecules made mostly of carbon and hydrogen that store energy.

Chitin is a structural polysaccharide used by arthropods to build their exoskeletons. Chitin is also found in fungi as well. Cellulose is the structural component found in the cell walls of plants.

Starch is a storage polysaccharide in plants. It is a polymer consisting solely of glucose. Glucose is a source of fuel for cells; therefore, starch is stored for energy.

Mannose is an epimer of glucose, and is a carbohydrate. Typically, molecule names ending in "–ose" will be carbohydrates. The other answers each belong to a different category of macromolecule: cholesterol is a lipid, miRNA is a nucleic acid, and lipase is a protein.

Just as the suffix "ose" signifies a carbohydrate, the suffix "ol" indicates a lipid and the suffix "ase" indicates a protein.