Chapter 3: The Molecules of Life

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Vocabulary

Organic compounds

Compounds that contain carbon

Organic chemistry

Study of organic compounds

Hydrocarbons

Organic molecules that contain only carbon and hydrogen

Functional groups

Atoms that form the chemically reactive part of a molecule

Macromolecules

Very large molecule in a living organism: protein, polysaccharide, lipid, nucleic acid

Polymer

A large molecule consisting of many identical or similar molecular units (monomers) covalently joined together in a chain

Monomer

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

Dehydration synthesis(condensation)

Chemical process in which a polymer forms as monomers are linked together by the removal of water molecules

Hydrolysis

Chemical process in which macromolecules are broken down by the chemical addition of water molecules to the bonds linking their monomers; an essential part of digestion

Carbohydrates

Biological molecule consisting of simple single-monomer sugars (monosaccharides), two-monomer sugars (disacchsride) and other multi-unit sugars (polysaccharides)

Monosaccharides

Smallest kind of sugar molecule; single sugar unit

Isomers

Organic compounds with the same molecular formula but different structures and thus different properties

Disaccharides

Sugar molecule consisting of two monosacccharides linked by a dehydration (condensation) reaction

Polysaccharides

Carbohydrate polymer consisting of hundreds to thousands of monosaccharides linked by covalent bonds

Starch

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

Glycogen

A complex, extensively branched polysaccharide made up of glucose monomers; serves as as 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

Hydrophilic

"water-loving"; pertaining to polar or charged molecules (or parts of molecules) that are soluble in water

Hydrophobic

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

Fat

A large lipid molecule made from an alcohol called glycerol and three fatty acids; a trigyceride; Most fats function as energy-storage

Triglyceride

A fat that consists of a molecule of glycerol linked to three fatty acid molecules

Unsaturated

Refers to fats and fatty acids whose hydrocarbon chains lack the maximum number of hydrogen atoms and therefore have one or more double covalent bonds. Unsaturated fats and fatty acids 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. Saturates fats and fatty acids solidify at room temperature

Atherosclerosis

A cardiovascular disease where growths called plaques develop on inner artery walls narrowing their diameter

hydrogenation

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

Trans fat

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

Steroids

Type of lipid whose carbon skeleton is in the form of four fused rings; three 6-sided rings and on 5-sided ring; examples include cholesterol, testosterone, estrogen

Anabolic steroids

Synthetic variant of the male hormone testosterone that mimics some of its side effects

Protein

A biological polymer constructed from amino acids monomers

Amino acid

An organic molecule containing a carboxyl group and an amino group; protein monomers

Enzyme

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

Peptide bond

Covalent linkage between two amino acid molecules in a polypeptide; formed by dehydration reaction

Polypeptide

A chain of amino acids linked by peptide bonds

Primary structure

First level of protein structure; specific sequence of amino acids making up a polypeptide

Denaturation

Process where a protein loses its specific conformation and thus its function; separation of strands in the DNA double helix; can be caused by changes in pH, salt concentration, high temperature

Nucleic acids

Polymer consisting of many nucleotide monomers

DNA

Double-stranded helical macromolecule consisting of nucleotide monomers with the sugar deoxyribose and nitrogen bases A,T,G,C

RNA

Nucleic acid consisting of nucleotide monomers with a ribose sugar and nitrogenous bases adenine, cytosine, guanine and uracil

Nucleotide

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

Nitrogenous base

A molecule that contains nitrogen and has the chemical properties of a base

Sugar-phosphate backbone

Alternating chain of sugar and phosphate attached to nitrogenous bases

Double helix

Native form of DNA; two polynucleotide chains held together with hydrogen bonds and wound into a spiral shape

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