Water Water has a high heat capacity, and a high heat of vaporization. It is called the universal solvent because of its general solvent properties. Water forms hydration layers, which are layers of water molecules that insulate large charged molecules.
Hydrolysis reactions are decompositionreactions whereby water is added to eachbond to be brokenA dehydration synthesis reaction involvesthe removal of a water molecule for everybond formed.
Salts A salt is an ionic compound containing cations other than H+ and anions other than the OH-. Electrolytes are substances that conduct an electrical current in solution.
Acids and bases Acids are proton donors, that dissociate to release hydrogen ions and anions. Bases are proton acceptors, that dissociate to produce hydroxides and cations. HCO3- and NH3 are important bases in the human body.
pH is a measure of hydrogen ionconcentration of a solution (in moles perliter). A pH of 7 is neutral; a higher pH isalkaline, and a lower pH is acidic.Normal blood pH is 7.35-7.45.
HCl + NaOH -> NaCl + H2O is anexample of a neutralization reaction.Buffers help to prevent excessivechanges in the pH of body fluids.
Acids that dissociate completely areknown as strong acids, whereas acids thatdo not dissociate completely are knownas weak acids.
Strong bases dissociate easily in waterand quickly tie up H+ whereas weak basesionizes incompletely and reversibly.H2CO3 -> HCO3- + H+ is an example of abuffer system.
Carbohydrates Carbohydrates are biomolecules that contain carbon, hydrogen and oxygen in the ratio CH2O. Monosaccharides are simple sugars containing from three to seven carbon atoms.
Galactose and fructose are isomers ofglucose, which means they have the samemolecular formula by their atoms arearranged differently.
A disaccharide is formed when twomonosaccharides are joined bydehydration synthesis.Disaccharides must be broken down byhydrolysis into monosaccharides to beabsorbed by the body.
Polysaccharides are long chains of simplesugars linked together by dehydrationsynthesis, to create polymers.
Lipids Lipids are organic compounds that are insoluble in water but dissolve readily in other lipids and in organic solvents. Neutral fats, composed of fatty acid chains and glycerol, are found chiefly in fatty tissue; they serve as insulation and reserve body fuel.
Neutral fats are called triglyceridesbecause of the 3:1 fatty acid to glycerolratio.Saturated fatty acid chains have onlysingle covalent bonds between carbonatoms.
Fatty acids that contain one or moredouble bonds between carbon atoms areunsaturated.
Phospholipids are modified triglycerideswith a phosphorus-containing group andtwo fatty acid chains.Steroids are flat molecules made of fourinterlocking hydrocarbon rings, the mostimportant of which is cholesterol.
Eicosanoids are derived from a 20-carbonfatty acid, most important of which arethe prostaglandins.
Proteins Proteins are the basic structural material of the body, although some play functional roles. The building blocks of proteins are molecules called amino acids, which are composed of an amine, and a carboxylic acid.
Peptide bonds join amino acid monomerstogether by dehydration synthesis to formproteins.
Most proteins are macromolecules, whichcontain 100 to 10,000 amino acids.The most common type of secondaryprotein structure is the alpha helix whichresembles a slinky.
The beta pleated sheet is another type ofsecondary structure, but instead of coiling ithas a ribbon-like structure.
Fibrous proteins are extended and strand-like, most exhibit secondary structure,and are insoluble in water.Fibrous proteins are also known asstructural proteins, because they are thechief building blocks of the body.
Globular proteins are spherical structureswith tertiary or quaternary structure, alsoknown as functional proteins.
When the hydrogen bonds of proteinsbreak due to environmental stresses, theprotein becomes denatured.When functional protein becomedenatured, they lose their active sites andcan no longer perform their physiologicalroles.
Enzymes are globular proteins that act asbiological catalysts.A holoenzyme is composed of a proteinportion called an apoenzyme, and a nonprotein portion called a cofactor.Organic cofactors are derived fromvitamins, and are called coenzymes.
Enzymes lower the activation energynecessary for a reaction to proceed.A substrate is the substance upon whichthe enzyme acts.
Nucleic acids (DNA and RNA) Nucleic acids are composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus, and are the largest molecules in the body. Nucleotides are the structural units of nucleic acids, and consist of five varieties of nitrogenous bases: adenine, guanine, cytosine, and thymine.
Two major classes of nucleic acids aredeoxyribonucleic acid (DNA), andribonucleic acid (RNA).DNA is a long, double-stranded polymercoiled into a shape that resembles a spiralstaircase, called a double helix.
The bases that bond to each other arecalled complementary bases, and alwaysbond to the same partner.
Adenosine triphosphate Energy released during the breakdown of glucose is captured and stored in the high energy phosphate bonds of adenosine triphosphate (ATP).