2.3 Biological Molecules

This set of vocabulary flashcards covers biological macromolecules (carbohydrates, lipids, proteins, and nucleic acids), their structures, functions, and key examples as described in the lecture notes.

Biological macromolecules

Large molecules necessary for life that are built from smaller organic molecules, classified into four major types: carbohydrates, lipids, proteins, and nucleic acids.

Organic molecules

Molecules that contain carbon bound to hydrogen and may also contain oxygen, nitrogen, and other minor elements.

Methane

The simplest organic carbon molecule, consisting of a carbon atom bound to four hydrogen atoms, with the formula $CH_4$.

Carbohydrates

Macromolecules with the general formula $(CH_2O)_n$, where the ratio of carbon to hydrogen to oxygen is $1:2:1$, primarily providing energy to the body.

Monosaccharides

Simple sugars, such as glucose, galactose, and fructose, usually containing three to six carbon atoms and often ending in the suffix -ose.

Isomers

Molecules that share the same chemical formula but differ structurally and chemically, such as glucose, galactose, and fructose which are all $C_6H_{12}O_6$.

Disaccharides

Carbohydrates formed when two monosaccharides undergo a dehydration reaction, such as lactose, maltose, and sucrose.

Starch

The stored form of sugars in plants, comprised of amylose and amylopectin, which are both polymers of glucose.

Glycogen

A highly branched storage form of glucose in humans and other vertebrates, typically stored in liver and muscle cells.

Cellulose

An abundant natural biopolymer that makes up plant cell walls, providing structural support and rigidity to the cell.

Cellulase

An enzyme secreted by certain bacteria in the digestive systems of herbivores that breaks down cellulose into glucose monomers.

Chitin

A nitrogenous carbohydrate that forms the exoskeleton of arthropods like insects, spiders, and crabs.

Lipids

A diverse group of nonpolar hydrocarbons that are hydrophobic ("water-fearing") and insoluble in water.

Triglyceride

A fat molecule consisting of two main components: a glycerol backbone and three fatty acids.

Saturated fatty acid

A fatty acid chain with only single bonds between neighboring carbons, maximizing the number of hydrogen atoms attached to the carbon skeleton.

Unsaturated fatty acid

A fatty acid hydrocarbon chain that contains at least one double bond, which creates a "kink" preventing tight packing; usually liquid at room temperature.

Trans-fat

Fats created through artificial hydrogenation where double bonds in the cis-conformation are converted to the trans-conformation, appearing in foods like margarine and shortening.

Essential fatty acids

Fatty acids required by the human body that cannot be synthesized by it, such as omega-3 and omega-6 fatty acids.

Phospholipids

The major constituent of the plasma membrane, composed of two fatty acid chains and a phosphate group attached to a glycerol backbone.

Steroids

Hydrophobic molecules characterized by a structure of four linked carbon rings, such as cholesterol.

Proteins

One of the most abundant organic molecules in living systems, consisting of polymers of amino acids arranged in a linear sequence.

Enzymes

Proteins that act as catalysts in biochemical reactions, each specific for the substrate upon which it acts.

Hormones

Chemical signaling molecules, typically proteins or steroids, that regulate physiological processes like growth, metabolism, and reproduction.

Amino acids

The monomers of proteins, each having a central carbon bonded to an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom, and a variable R group.

Peptide bond

The covalent bond formed by a dehydration reaction between the carboxyl group of one amino acid and the amino group of another.

Primary protein structure

The unique sequence and number of amino acids in a polypeptide chain.

Secondary protein structure

The folding patterns resulting from hydrogen bonds between the backbone of the polypeptide, most commonly the alpha-helix ($\\alpha$-helix) and beta-pleated sheet ($\\beta$-pleated sheet).

Tertiary protein structure

The unique three-dimensional structure of a polypeptide caused by chemical interactions between various R groups.

Quaternary protein structure

The structure formed by the interaction of several polypeptide subunits, such as in hemoglobin.

Denaturation

A process where a protein loses its shape and function due to changes in temperature, pH, or exposure to chemicals.

Cytochrome c

An essential protein in harvesting energy from glucose that is used by scientists to assess evolutionary relationships due to its highly conserved sequence.

Nucleic acids

Macromolecules like DNA and RNA that carry the genetic blueprint of a cell and instructions for its functioning.

Nucleotides

The monomers of nucleic acids, each comprising a nitrogenous base, a pentose (five-carbon) sugar, and a phosphate group.