Biology Vocab Chapter 2

Atom

The basic unit of matter

Nucleus

The center of an atom which contains protons and neutrons, the structure that contains DNA

Electron

Negatively charged particle located in space surrounding nucleus.

Element

A pure substance that consists entirely of one type of atom.

Isotopes

Atoms of the same number that differ in number of neutrons they contain

Compound

A substance formed by the chemical combination of two or more elements in definite proportions

Ionic bond

Chemical bond formed when one or more electrons are transferred from one atom to another

Ions

An atom that has a positive or negative charge

Covalent bond

Type of bond between atoms in which the electrons are shared

Molecule

The smallest unit of most compounds that is a result of the joining of atoms by covalent bonds

Van der Waals force

Slight attraction that develops between oppositely charged regions of nearby molecules

Hydrogen bond

The attraction between a hydrogen atom with a partial positive charge and another atom with a partial negative charge

Cohesion

The attraction between molecules of the same substance

Adhesion

The attraction between molecules of different substances

Mixture

A material composed of two or more elements or compounds that are physically mixed together but not chemically combined

Solution

Type of mixture in which all the components are evenly distributed

Solute

The substance that is dissolved

Solvent

The substance in which the solute dissolves

Suspensions

Mixture of water and now dissolved material

PH scale

Scale with values 0 to 14; used to measure the concentration of H+ ions in a solution; a pH 0 to 7 is acidic, a pH of 7 is neutral, a pH of 7 to 14 is basic.

Acid

Any compound that releases H+ ions into solution

Base

A compound that produces hydroxide (OH-) ions in solution

Buffers

Weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH

Monomer

Small chemical unit that makes up a polymer

Polymer

Molecule composed of many monomers; make up macromolecules

Carbohydrates

Compound made of carbon, hydrogen, and oxygen atoms; types of nutrients that are the major source of energy to the body

Lipids

Macromolecule made mostly from carbon and hydrogen atoms; includes fats, oils, and waxes

Nucleotides

Monomers that consist of three components: a 5-carbon sugar, a phosphate group (-PO4), and a nitrogenous base

Nucleic acids

Polymers assembled from nucleotides

Proteins

Macromolecules containing nitrogen as well as carbon, hydrogen, and oxygen

Amino acids

Compounds with an amino group (-NH2) on one end and a carboxyl group (-COOH) on the other end

Chemical reaction

A process that changes, or transforms, one set of compound into another

Reactants

Elements or compounds that engage in a chemical reaction

Products

Elements or compounds produced by a chemical reaction

Activation energy

The energy that is needed to get a reaction started

Catalyst

A substance that speeds up the rate of a chemical reaction without being consumed by the reaction

Enzymes

Biological catalysts, and most enzymes are proteins

Substrates

The reactants of enzyme-catalyzed reactions