Biochemistry: Molecules of Life and Their Functions

Organic Compound

A compound that consists primarily of carbon and hydrogen atoms.

Hydrocarbon

A molecule consisting solely of carbon and hydrogen atoms.

Carbon's Bonding Versatility

Carbon can bond stably with many elements and has four vacancies in its outer shell.

Functional Group

An atom (other than hydrogen) or a small molecular group covalently bonded to a carbon atom.

Hydroxyl Group (—OH)

A polar functional group that increases a molecule's solubility in water.

Methyl Group (—CH₃)

A nonpolar functional group that can dampen the effect of polar groups.

Carboxyl Group (—COOH)

A polar and acidic functional group found in amino acids and fatty acids.

Amine (—NH₂) and Amide Groups

Functional groups that make nucleotide bases basic; also found in proteins.

Phosphate Group (—PO₄)

A polar, acidic group found in nucleic acids and phospholipids.

Metabolism

The collective term for all enzyme-mediated chemical reactions in a cell.

Monomers vs. Polymers

Monomers are simple organic building blocks; polymers are larger molecules consisting of repeated monomers.

Enzyme

An organic molecule (usually a protein) that speeds up a chemical reaction.

Condensation (Dehydration)

A metabolic reaction where an enzyme joins two monomers, forming a covalent bond.

Hydrolysis

A metabolic reaction where an enzyme breaks a polymer into monomers.

Structural Formula Models

Represent atoms and bonds with variations for clarity.

Ball-and-stick Model

A 3D representation showing the spatial arrangement of atoms and bonds.

Space-filling Model

A model that reveals the overall shape of a molecule.

Surface and Ribbon Models

Surface models reveal crevices and folds; ribbon models show the folding of the backbone.

Carbohydrate Composition

Organic compounds consisting of carbon, hydrogen, and oxygen in a 1:2:1 ratio.

Monosaccharide

The simplest carbohydrate, often with a backbone of five or six carbons.

Disaccharide

An oligosaccharide consisting of two sugar monomers.

Cellulose Structure and Function

A polysaccharide of glucose monomers linked by hydrogen-bonded straight chains.

Starch Structure and Function

A polysaccharide of glucose monomers that forms a coiled chain.

Glycogen Structure and Function

A highly branched polysaccharide of glucose monomers.

Chitin

A nitrogen-containing polysaccharide of modified glucose monomers.

Lipid Characteristics

Fatty, oily, or waxy organic compounds that are generally hydrophobic.

Fatty Acid Structure

Consists of a hydrophilic carboxyl group 'head' and a long hydrophobic hydrocarbon 'tail.'

Saturated Fatty Acids

Fatty acids with only single bonds in their hydrocarbon tails.

Unsaturated Fatty Acids

Fatty acids with one or more double bonds in their tails.

Triglyceride (Fat)

A molecule with three fatty acid tails bonded to a single glycerol head.

Cis vs. Trans Bonds

Cis bonds have hydrogen atoms on the same side; trans bonds have hydrogens on opposite sides.

Trans Fats

Fats containing trans bonds, often produced via partial hydrogenation.

Phospholipid Structure

A lipid with a hydrophilic phosphate-containing head and two hydrophobic tails.

Lipid Bilayer

A two-layered sheet of phospholipids that forms the structural foundation of all cell membranes.

Steroids

Lipids with no fatty acid tails and a backbone of four carbon rings.

Waxes

Water-repellent mixtures of lipids with long fatty acid tails.

Lipoprotein Particles

Clumps of proteins and lipids that allow hydrophobic molecules to move through blood.

Amino Acid Structure

The monomer of proteins, consisting of an amine group, a carboxyl group, and one of twenty variable 'R groups.'

Peptide Bond

A covalent bond formed by a condensation reaction between amino acids.

Polypeptide

A long chain of amino acids linked by peptide bonds.

Primary Structure

The unique linear sequence of amino acids in a polypeptide chain.

Secondary Structure

The 3D patterns of coils and sheets formed by hydrogen bonds.

Tertiary Structure

The level where helices and sheets fold into functional domains.

Quaternary Structure

The association of multiple polypeptide chains to form a single functional molecule.

Denaturation

The process where a protein loses its three-dimensional shape.

Prion

A misfolded protein that can cause other proteins to misfold.

Glycoprotein

A protein with one or more oligosaccharides attached.

Nucleotide Monomers

The building blocks of nucleic acids.

Sugar Components

Ribose is the sugar in RNA nucleotides; deoxyribose is in DNA nucleotides.

Nitrogenous Bases

Components of nucleotides that are chemically basic.

Biological Information

Information encoded in a nucleic acid consists of the specific sequence of its nucleotide monomers.

Phosphorus Role

Phosphorus is essential for life as it is incorporated into nucleic acids.