Carbohydrates and Biomolecules

Yeast cell walls are composed primarily of chitin, a polysaccharide also found in fungal cell walls and insect exoskeletons. This is different from plant cell walls (cellulose) and bacterial cell walls (peptidoglycan).

RuDP stands for Ribulose Diphosphate (also called RuBP - Ribulose-1,5-bisphosphate), the 5-carbon molecule that accepts CO2 in the Calvin cycle's first step, catalyzed by the enzyme RuBisCO.

Among the given options, saccharine (saccharin) is the sweetest substance, being approximately 300-700 times sweeter than sucrose (table sugar). Sucrose is standard table sugar from sugarcane/beets. Fructose (fruit sugar) is about 1.2-1.8 times sweeter than sucrose. Glucose is less sweet than sucrose. While modern artificial sweeteners like sucralose and thaumatin are sweeter than saccharin, among these four options, saccharine is indeed the sweetest.

Common household sugar (table sugar) is chemically known as sucrose. Sucrose is a disaccharide composed of glucose and fructose molecules. Maltose and glucose are different types of sugars with distinct chemical structures.

Ribitol is a crystalline pentose alcohol formed by the reduction of ribose. It occurs naturally in the plant Adonis vernalis, as well as in the cell walls of Gram positive bacteria .It also contributes to the chemical structure of riboflavin.

Polysaccharides are polymeric carbohydrate structures, formed of repeating units (either mono- or di-saccharides) joined together by glycosidic bonds. These structures are often linear, but may contain various degrees of branching. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit.

The carbohydrate present in rice is primarily starch. Rice grains contain about 80-85% starch, which is a complex carbohydrate made of glucose molecules. Glucose, fructose, and insulin are not correct - glucose is a simple sugar, insulin is a hormone, and fructose is fruit sugar. Starch is the storage form of carbohydrate in plants like rice.

Monosaccharides are the most basic units of biologically important carbohydrates. These are the simplest form of sugar and are usually colourless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose (dextrose), fructose (levulose), galactose, xylose and ribose.

Fructose, or fruit sugar, is a simple monosaccharide found in many foods. It is one of the three important dietary monosaccharides along with glucose and galactose.

Glycosylation is the enzymatic process that attaches glycans to proteins, lipids, or other organic molecules. This enzymatic process produces one of the fundamental biopolymers found in cells (along with DNA, RNA, and proteins). Glycosylation is a form of co-translational and post-translational modification.

Galactose is a monosaccharide. When combined with glucose, through a dehydration reaction, the result is the disaccharide lactose. The hydrolysis of lactose to glucose and galactose is catalyzed by the enzyme lactase and β-galactosidase. This enzyme is produced by the lac operon in Escherichia coli.

Monosaccharides are the building blocks of disaccharides such as sucrose and polysaccharides (such as cellulose and starch). Further, each carbon atom that supports a hydroxyl group (except for the first and last) is chiral, giving rise to a number of isomeric forms all with the same chemical formula. For instance, galactose and glucose are both aldohexoses, but have different chemical and physical properties.

Gangliosides have at least three sugars, one of which must be sialic acid.

Lactulose is a synthetic, non-digestible sugar used in the treatment of chronic constipation and hepatic encephalopathy, a complication of liver disease. It is a disaccharide (double-sugar) formed from one molecule each of the simple sugars (monosaccharides) fructose and galactose.

N-Acetylglucosamine is part of a biopolymer in the bacterial cell wall, built from alternating units of GlcNAc and N-acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. This layered structure is called peptidoglycan (formerly called murein).