Chapter 3: The Molecules of Life

organic compounds

a chemical compound containing carbon and usually synthesized by cells

organic chemistry

chemistry involving organic compounds

hydrocarbons

a chemical compound composed only of the elements carbon and hydrogen

functional groups

the atoms that forms the chemically reactive part of an organic molecule

macromolecules

a giant molecule in a living organism; included proteins, polysaccharides, and nucleic acids

polymers

a large molecule consisting of many identical or similar molecular units, called monomers, covalently joined together in a chain

monomers

a chemical subunit that serves as a building block of a polymer

dehydration synthesis (condensation)

a chemical reaction that removes a molecule of water

hydrolysis

a chemical process in which macromolecules are broken down by the chemical addition of water molecules to the bonds linking their monomers; an esential part of digestion; the opposite of dehydration synthesis (adding water)

carbohydrates

a biological molecule consisting of simple single-monomer sugars (monosaccharides), 2-monomer sugars (disaccharides), and other multi-unit sugars (polysaccharides)

monosaccharides

the smallest kind of sugar molecule; a single unit-sugar; also known as simple sugar; are the complex building blocks of more complex sugars and polysaccharides

polysaccharides

a carbohydrate polymer consisting of many monosaccharides (sugars) linked by covalent bonds

disaccharides

a sugar molecule consisting of two monosaccharides linked by dehydration reaction

isomers

molecules that have the same molecular formula but different structures

starch

a storage polysaccharide found in the roots of plants and certain other cells; a polymer of glucose

glycogen

a complex, extensively branched polysaccharide made up of many glucose monomers; serves as an energy-storage molecule in liver and muscle cells

cellulose

a large polysaccharide composed of many glucose monomers linked into cable like fibrils that provide structural support in plant cell walls because cellulose cannot be digested by animals, it acts as roughage or fiber, in the diet

hydrophilic

"water-loving"; pertaining to polar, or charged, molecules (or parts of molecules) which are soluable in water

lipid

an organic compound consisting mainly of carbon and hydrogen atoms linked by nonpolar convalent bonds and therefore mostly hydrophobic and insoluble in water; includes fats, waxes, phopholipids, and steroids

hydrophobic

"water-fearing"; pertaining to nonpolar molecules (or parts of molecules) which do not dissolve in water

fat

a large lipid molecule made from an alcohol called glycerol and three fatty acids; a triglyceride; most fats function as energy storage molecules

triglyceride

a dietary fat, which consists of a molecule of glycerol linked to three molecules of fatty acid

unsaturated

pertaining to fats and fatty acids whose hydrocarbon chains lack the maximum number of hydrogen atoms and therefore have one or more double covalent bonds; do not solidify at room temperature

saturated

pertaining to fats and fatty acids whose hydrocarbon chains contain the maximum number of hydrogens and therefore have no double covalent bonds saturated fats and fatty acids solidify at room temperature

atherosclerosis

a cardiovascular disease in which growths called plaques develop on the inner walls of the arteries narrowing the passageways through which blood can flow

hydrogenation

the process of converting unsaturated fats to saturated fats by the addition of hydrogen

trans fat

an unsaturated fatty acids produced by the partial hydrogenation of vegetable oils and present in hardened vegetable oils; most margarines, commercial baked foods, and many fried foods

steroids

a type of lipid whose carbon skeleton is in the form of four fused rings: 3 6-sides rings and one 5-sided ring (i.e: choleserol, testosterone, and estrogen)

anabolic steroids

synthetic variants of testosterone

protein

a biological polymer constructed from amino acid monomers

enzyme

a protein that serves as a biological catalyst, changing the rate of a chemical reaction without itself being changed in the process

amino acid

an organic molecule containing a carboxyl group, an amino group, a hydrogen atom, and a variable side chain; serves as the monomer of proteins

peptide bond

the covalent linkage between two amino acid units in a polypeptide, formed by a dehydration reaction between two amino acids

polypeptide

a chain of amino acids linked by peptide bonds

primary structure

the first level of protein structure; the specific sequence of amino acids making up a polypeptide chain

denaturation

a process in which a protein unravels, losing its specific conformation and hence function; can be caused by changes in pH or salt concentration or by high temperature; also refers to the separation of the two strands of the DNA double helix, caused by similar factors

nucleotide

an organic monomer consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group; are the building blocks of nucleic acids

nucleic acids

macromolecules that provide the directions for building proteins

DNA

deoxyribonuclic acid; the genetic material that organisms inherit from their parents; a double-stranded helical macromolecule consisting of nucleotide monomers with deoxyribose sugar, a phosphate group, and the nitrogenous bases adenine (A), cytosine (C), guanine (G) and thymine (T)

RNA

ribonucleic acid; a type of nucleic acid consisting of nucleotide monomers with a ribose sugar, a phosphate group, and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; function in protein syntheisis and the the genome of some viruses

nitrogeneous base

nitrogen containing; accepts hydrogen ions (H+) in aqueous solutions

sugar-phosphate backbone

the alternating chain of sugar and phosphate to which DNA and RNA nitrogenous bases are attached

gene

A specific stretch of DNA that programs the amino acid sequence of a polypeptide

double helix

the form assumed by DNA in living cells, referring to its two adjacent polynucleotide strands wound into a spiral shape