Biochemistry

BiochemistryBiochemistry

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 decomposition reactions whereby water is added to each bond to be broken

A dehydration synthesis reaction involves the removal of a water molecule for every bond 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 ion concentration of a solution (in moles per liter). A pH of 7 is neutral; a higher pH is alkaline, and a lower pH is acidic. Normal blood pH is 7.35-7.45.

HCl + NaOH -> NaCl + H2O is an example of a neutralization reaction.

Buffers help to prevent excessive changes in the pH of body fluids.

Acids that dissociate completely are known as strong acids, whereas acids that do not dissociate completely are known as weak acids.

Strong bases dissociate easily in water and quickly tie up H+ whereas weak bases ionizes incompletely and reversibly.

H2CO3 -> HCO3- + H+ is an example of a

buffer system.

Organic compounds

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 of glucose, which means they have the same molecular formula by their atoms are arranged differently.

A disaccharide is formed when two monosaccharides are joined by dehydration synthesis.

Disaccharides must be broken down by hydrolysis into monosaccharides to be absorbed by the body.

Polysaccharides are long chains of simple sugars linked together by dehydration synthesis, 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 triglycerides because of the 3:1 fatty acid to glycerol ratio.

Saturated fatty acid chains have only single covalent bonds between carbon atoms.

Fatty acids that contain one or more double bonds between carbon atoms are unsaturated.

Phospholipids are modified triglycerides with a phosphorus-containing group and two fatty acid chains.

Steroids are flat molecules made of four interlocking hydrocarbon rings, the most important of which is cholesterol.

Eicosanoids are derived from a 20-carbon fatty acid, most important of which are the 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 monomers together by dehydration synthesis to form proteins.

Most proteins are macromolecules, which contain 100 to 10,000 amino acids.

The most common type of secondary protein structure is the alpha helix which resembles a slinky.

The beta pleated sheet is another type of secondary structure, but instead of coiling it has 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 as structural proteins, because they are the chief building blocks of the body.

Globular proteins are spherical structures with tertiary or quaternary structure, also known as functional proteins.

When the hydrogen bonds of proteins break due to environmental stresses, the protein becomes denatured.

When functional protein become denatured, they lose their active sites and can no longer perform their physiological roles.

Enzymes are globular proteins that act as biological catalysts.

A holoenzyme is composed of a protein portion called an apoenzyme, and a non protein portion called a cofactor.

Organic cofactors are derived from vitamins, and are called coenzymes.

Enzymes lower the activation energy necessary for a reaction to proceed.

A substrate is the substance upon which the 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 are deoxyribonucleic acid (DNA), and ribonucleic acid (RNA).

DNA is a long, double-stranded polymer coiled into a shape that resembles a spiral staircase, called a double helix.

The bases that bond to each other are called complementary bases, and always bond 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).