Chapter 2 Atoms, Molecules, and Life Flashcards
Acid
A substance that releases hydrogen ion (H+) into a solution; a solution with a pH of less than 7.
Amino Acid
The individual subunit of which proteins are made, composed of a central carbon atom bonded to an amino group, a carboxyl group. a hydrogen atom, and a variable group of atoms denoted by the letter R.
Atom
The smallest particle of an element that retains the properties of the element.
Atomic Nucleus
The central region of an atom, consisting of protons and neutrons.
Atomic Number
A number of protons in the nuclei of all atoms of a particular element.
Base
(1) a substance capable of combining with and neutralizing H+ ions in a solution; a solution with a pH of more than 7; (2) in molecule genetrics, one of the nitrogen-containing, single or double ringed structures that distinguishes one nucleotide from another. In DNA, the bases are adenine, guanine, cytosine, and thymine.
Buffer
A compound that minimizes changes in pH by reversibly taking up or releasing H+ ions.
Carbohydrate
A compound composed of carbon, hydrogen, and oxygen, with the approximate chemical formula includes sugars and starches.
Chemical Bond
The process that forms and breaks chemical bonds that hold atoms together.
Chemical Reaction
The process that forms and breaks chemical onds that hold atoms together.
Cohesion
The tendency of the molecules of a substance to stick together.
Covalent Bond
A chemical bond between atoms in which electrons are shared.
Dehydration Synthesis
A chemical reaction in which two molecules are joined by a covalent bond with the simultaneous removal of a hydrogen atom from one molecuyle and a hydroxly group from the other, forming water; the reverse of hydrolysis.
Denature
To disrupt the secondary and or tertiary structure of a protein while leaving its aino acid sequence intact. Denatured proteins can no longer perform their biological functions.
Electron
A subatomic particle, found in an electron shell outside the nucleus of an atom, that bears a unit of negative charge and very little mass.
Electron Shell
A region within which electrons orbit that corresponds to a fixed energy level at a given distance from the atomic nucleus of an atom.
Element
A substance thatt cannot be broken down, or converted, to a simpler substance by ordinary chemical means.
Functional Group
One of several groups of atoms commonly found in an organic molecule, including hydrogen, hydroxyl, amino, carboxyl, and phosphate groups, that dertmine the characteristics and chemical reactivity of the molecule.
Hydrogen Bond
The weak attraction between a hydrogen atom that bears a partial positive charge (due to polar covalent bonding with another atom) and another atom, normally oxygen or nitrogen, that bearts a partial negative charge; hydrogen bonds may form between atoms of a single molecule or of different molecules
Hydrolysis
The chemical reaction that breaks a covalent bond by means of the addition of hydrogen to the atom on one side of the original bond and a hydroxyl to the atom on the other side; the reverse of dehydration synthesis.
Ion
A charged atom or molecule; an atom or molecule that either has an excess of electrons (and hence is negatively charged) or has lost electrons (and is positively charged).
Ionic Bond
A chemical bond formed by the eletrical attraction between positively and negatively charged ions.
Isotope
One of several forms of a single element, the nuclei of which contain the same number of protons but different numbers of neutrons.
Lipid
One of a number of organic molecules containing large nonpolar regions composed solely of carbon and hydrogen, which make lipids hydrophobic and insoluble in waterl includes oils, fats, waxes, phospholipids, and steroids.
Molecule
A particle composed of one or more atoms held together by chemical bonds; the smallest particle of a compound that displays all of the properties of that compound.
Neutron
A subatomic particle that is found in the nuclei of atoms, bears no charge, and has a mass approximately equal to that of a proton.
Nonpolar Molecule
A molecule bound by covalent bonds in which eletrical charge is symmetrically distributed, so that no portion of the molecule is eletrically charged relative to other portions.
Nucleic Acid
An organic molecule composed of nucleotide subunits; the two common types of nuclei acids are ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).
Organic Molecule
A molecule that contains both carbon and hydrogen.
pH Scale
A scale, with values from 0 to 14, used for the relative acidity of a solution; at pH 7 a solution is netrual, pH 0 to 7 acidic, and pH 7 to 14 is basicl each unit on the scale represents a tenfold change in H+ concentration.
Polar Molecule
A molecule bound by covalent bonds in which electrical change is asymmetrically distrubuted, so that the eletrical charge differes in different portions of the molecule.
Protein
A polymer of amino acids joined by peptide bonds.
Proton
A subatomic particle that is found in the nuclei of atoms, bears a unit of positive charge, and has a relatively large mass, roughly equal to the mass of the neutron.
Radioactive
Pertaining to an atom with an unstable nucleus that spontaneously disintegrates, with the emission of radiation.
Solvent
A liquid capable of dissolving (uniformly dispersing) other substances in itself.
Surface Tension
A tendency of a liquid to resist penetration by objects at its interface with the air, due to cohesion between molecules of a liquid.
Wax
A lipid composed of fatty acids covalently bonded to long-chain alcohols.
