2.3 Biological Molecules from Concepts of Biology

Flashcards covering carbon bonding, carbohydrates, lipids, proteins, and nucleic acids as described in the provided textbook section.

Biological macromolecules

Large molecules necessary for life built from smaller organic molecules, including carbohydrates, lipids, proteins, and nucleic acids.

Organic

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

Methane

The simplest organic carbon molecule, represented by the chemical formula $CH_4$.

Carbohydrates

Biological molecules represented by the formula $(CH_2O)_n$, where the ratio of carbon to hydrogen to oxygen is $1:2:1$.

Monosaccharides

Simple sugars, such as glucose, typically containing between three and six carbon atoms.

Hexoses

Monosaccharides that contain six carbon atoms, such as glucose, galactose, and fructose.

Isomers

Molecules like glucose, galactose, and fructose that share the same chemical formula ($C_6H_{12}O_6$) but differ structurally and chemically.

Dehydration reaction

A process where the hydroxyl group ($-OH$) of one monosaccharide combines with a hydrogen atom of another, releasing a molecule of water ($H_2O$) and forming a covalent bond.

Disaccharides

Sugar molecules formed from two monosaccharides, including lactose, maltose, and sucrose.

Polysaccharide

A long chain of monosaccharides linked by covalent bonds, which can be branched or unbranched.

Starch

The storage form of sugars in plants, composed of amylose and amylopectin polymers.

Glycogen

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

Cellulose

A structural biopolymer that makes up plant cell walls, providing rigidity and high tensile strength.

Chitin

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

Lipids

A diverse group of nonpolar hydrocarbons that are hydrophobic and insoluble in water.

Triglyceride

A fat molecule consisting of a glycerol backbone attached to 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 that contains one or more double bonds in the hydrocarbon chain, usually liquid at room temperature.

Hydrogenation

The industrial process of bubbling hydrogen gas through oils to solidify them, sometimes converting cis-conformation double bonds into trans-conformation.

Phospholipids

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

Steroids

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

Proteins

Abundant organic molecules consisting of polymers of amino acids arranged in a linear sequence, performing structural, regulatory, contractile, or protective functions.

Enzymes

Biological catalysts, usually proteins, that are specific for a substrate and function to break, rearrange, or form molecular bonds.

Amino acids

The monomers of proteins, consisting of 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 between the carboxyl group of one amino acid and the amino group of another through a dehydration reaction.

Denaturation

The loss of a protein's shape and function caused by changes in temperature, pH, or exposure to chemicals.

Primary structure

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

Secondary structure

Folding patterns like the alpha ($\alpha$)-helix and beta ($\beta$)-pleated sheet, held in shape by hydrogen bonds.

Tertiary structure

The unique three-dimensional structure of a polypeptide resulting from chemical interactions among R groups.

Quaternary structure

The protein structure formed by the interaction of multiple polypeptide subunits.

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 composed of a nitrogenous base, a pentose sugar, and a phosphate group.

DNA

Deoxyribonucleic acid; the double-stranded genetic material found in all living organisms, structured as a double helix.