Chapter 02: Biological Molecules

Vocabulary flashcards based on lecture notes on Biological Molecules, covering topics such as carbohydrates, proteins, and their structures and functions.

Benedict's Test

A test for glucose where a dirty green, yellow, or red precipitate indicates the presence of glucose.

Fehling's Solution Test

A test for glucose where red precipitates are formed when glucose is present and heated.

Molisch's Test

A test for disaccharide sugars where a purple ring forms at the junction of two solutions, indicating the presence of a disaccharide sugar.

Proteins

Critical components in cells required for structure, functioning, maintenance, and regulation of body systems; composed of C, H, O, and N, and sometimes P, S, Fe, I, and Mg.

Amino Acids

Building blocks of proteins, containing a central carbon atom (alpha carbon) attached to a hydrogen atom, an amino group (-NH2), a carboxyl group (-COOH), and a variable R group.

Essential Amino Acids

Amino acids that cannot be produced by the body and must be obtained through diet; found in foods like milk, egg, fish, chicken, meat, vegetables, and lentils.

Glycosidic Bond

Covalent chemical bonds between two glycosides, formed through a condensation reaction where a water molecule is released.

Reducing Sugar

A carbohydrate capable of being oxidized and causing the reduction of other substances without prior hydrolysis; includes all monosaccharides and maltose/lactose disaccharides.

Non-Reducing Sugar

A carbohydrate unable to be oxidized and does not reduce other substances; includes sucrose and polysaccharides.

Sucrose Glycosidic Linkage

Formed by the condensation of a-glucose and B-fructose, resulting in an a-1,2-glycosidic linkage.

Maltose Glycosidic Linkage

Formed by the condensation of two molecules of a-glucose, resulting in an a-1,4-glycosidic linkage.

Lactose Glycosidic Linkage

Formed by the condensation of B-galactose and B-glucose, resulting in a B-1,4-glycosidic linkage.

Polysaccharides

Carbohydrates that yield more than ten monosaccharide units upon hydrolysis; function as food/energy stores and structural materials.

Homopolysaccharides

Polysaccharides composed of only one kind of monosaccharide; examples include starch, glycogen, cellulose, and chitin.

Heteropolysaccharides

Polysaccharides composed of different kinds of monosaccharides; examples include agar, pectin, and peptidoglycan.

Starch

A homopolysaccharide made of a-glucose monomers, serving as a storage carbohydrate in plants.

Amylose

An unbranched form of starch with a linear chain of glucoses linked by a-1,4-glycosidic linkages; soluble in hot water.

Amylopectin

A branched form of starch with a linear chain of glucoses and branches attached by a-1,6-glycosidic linkages; insoluble in water.

Glycogen

A homopolysaccharide composed of multiple a-glucose monomers, serving as a storage carbohydrate in animals (animal starch), stored mainly in the liver and muscles.

Cellulose

A homopolysaccharide formed by the condensation of hundreds of B-glucoses, serving as the structural carbohydrate of plants and a major constituent of plant cell walls.

Chitin

A homopolysaccharide and a structural carbohydrate found in the cell walls of fungi and in the exoskeleton of arthropods; a derivative of N-acetylglucosamine.

Iodine Test for Starch

A biochemical test where a dark blue-black coloration indicates the presence of starch.

Iodine Test for Glycogen

A biochemical test where a red coloration indicates the presence of glycogen.

Cellulose Digestion

Cannot be digested by human body, but it works as roughage or fiber so it prevents abnormal absorption of food in intestine. However, herbivore animals have some symbiotic bacteria that secrete cellulose enzyme for its digestion.

Disaccharide Sugar

A sugar composed of two monosaccharides joined by a glycosidic bond and produces a purple ring at the junction of two solutions during the Molisch's test.

Alpha Carbon

The central carbon atom in an amino acid to which a hydrogen atom, an amino group, a carboxyl group, and a variable R group are attached.

Glycosidic Linkage

Is also named alpha or beta on the basis of alpha or beta type of first sugar involved in linkage.

Starch location

Is mainly stored in root, stem and seeds. Cereal grains and potato tubers are rich sources of starch in human diet.

Chitin location

Found in the cell walls of fungi and in the exoskeleton of arthropods

Most abundant organic molecule on earth

cellulose