Chapter 3: Carbon and the Molecular Diversity of LIfe

Organic Compound

A compound containing carbon

Macromolecules

Critically important large molecules of all living things (carbohydrates, lipids, proteins, and nucleic acids)

Hydrocarbons

Organic molecules consisting of only carbon and hydrogen

ATP

Adenosine triphosphate; an organic molecule called adenosine attached to a string of three phosphate groups. When a phosphate group is broken off, a high amount of energy is released.

Polymer

A long molecule consisting of many similar or identical building blocks linked by covalent bonds.

Monomer

The repeating units that serve as the building blocks of a polymer

Enzymes

specialized macromolecules (usually proteins) that speed up chemical reactions.

Dehydration Reaction

A reaction in which two molecules are covalently bonded to each other, with the loss of a water molecule

Hydrolysis reaction

The breaking apart of the covalent bonds between two monomers by the addition of a water molecule.

Carbohydrate

sugars and polymers of sugars

Monosaccharide

molecular formulas that are some multiple of the unit CH2O

Disaccharides

two monosaccharides joined together by a glycosidic linkage

Glycosidic linkage

a covalent bond formed between two monosaccharides by a dehydration reaction

Polysaccharide

macromolecules; polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages.

Starch

A polymer of glucose monomers, as granules within cells; made by plants

Glycogen

A polymer of glucose with many branches; made by animals

Cellulose

A polysaccharide that is a major component of the tough walls that enclose plant cells

Chitin

Polysaccharide used by arthropods to build their exoskeletons

Lipids

Molecules that mix poorly with water because they mostly consist of hydrocarbon regions

Fat

Constructed from two kinds of smaller molecules: glycerol and fatty acids

Fatty acid

A molecule that has a long carbon skeleton, usually 16 or 18 carbon atoms in length, with many hydrogen atoms bonded to it

Triglyceride

A fat with three fatty acid molecules joined to a glycerol molecule

Unsaturated fatty acid

A fatty acid which has one or more double bonds between carbon atoms on the hydrocarbon chain, resulting in one fewer hydrogen atom on each double-bonded carbon.

Saturated fatty acid

A fatty acid which has no double bonds between carbon atoms on the hydrocarbon chain, resulting in as many hydrogen atoms as possible bonded to the carbon skeleton

Phospholipids

The main constituent of cell membranes; a molecule with two fatty acid molecules and a phosphate group joined to the glycerol molecule

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings

Protein

A biologically functional molecule consisting of one or more polypeptides folded and coiled into a specific three-dimensional structure

Polypeptide

Polymer of amino acids; polypeptides make up proteins

Catalyst

Chemical agents that selectively speed up chemical reactions without being consumed by the reaction

Amino Acid

An organic molecule with both an amino group and a carboxyl group; the monomer of proteins

Peptide Bond

The covalent bond joining two amino acids together through a dehydration reaction

R group

The part of an amino acid that varies from one amino acid to the next. The R group gives the amino acid its chemical properties. For example, if the R group contains many carbon-hydrogen bonds, it is chemically nonpolar.

Primary structure of a protein

A protein's sequence of amino acids

Secondary structure of a protein

A protein's coils and folded patterns, which result from the hydrogen bonding of atoms in amino acids located near by each other

Tertiary structure of a protein

The overall shape of a polypeptide resulting from interactions between the R groups of the various amino acids

Alpha helix

A common secondary structure of a protein that results in a coil shape along the polypeptide chain

Beta-pleated sheets

A common secondary structure of a protein that results in two or more segments of the polypeptide chain lying side by side in a folded manner

Hydrophobic interaction

Contributes to the tertiary structure of a polypeptide chain, in which the nonpolar regions of the chain tend to cluster together at the core of the protein, away from water

Quaternary structure

The overall protein structure that results from the aggregation of the polypeptide subunits

Denaturation

In proteins, a process in which a protein loses its native shape due to the disruption of weak chemical bonds and interactions (such as hydrogen bonds), thereby becoming biologically inactive

Nucleic acid

A polymer made up of nucleotide monomers

Nucleotide

A monomer of nucleic acids; composed of a nitrogenous base, a five-carbon sugar, and a phosphate group

Deoxyribonucleic acid (DNA)

A type of nucleic acid, usually a double-stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), guanine (G), cytosine (C) and thymine (T); capable of being replicated and determining the inherited structure of a cell's proteins.

Ribonucleic acid (RNA)

A type of nucleic acid consisting of a polynucleotide made up of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), guanine (G), cytosine (C), or uracil (U); usually single-stranded; functions in protein synthesis, gene regulation, and as the genome of some viruses

Deoxyribose

The sugar found in DNA

Ribose

The sugar found in RNA

Nitrogenous base

A molecule containing one or two rings which include nitrogen atoms

Purine

The larger type of nitrogenous base with a six-membered ring of carbon and nitrogen atoms fused to a five-membered ring; includes adenine and guanine

Pyrimidine

The smaller type of nitrogenous base with a six-membered ring of carbon and nitrogen atoms; includes cytosine and thymine

Double helix

The overall shape of a DNA molecule, which has two polynucleotides or strands that spiral around an imaginary axis

Complementary base pairing

In DNA, adenine nitrogenous bases always pair with thymine from the second strand, while guanine always pairs with cytosine. This feature allows DNA to produce new strands by using one strand as a template to build the opposite strand.