Biology Chapter 2: The Chemistry of Life

Atom
The basic unit of matter

Nucleus
The center of the atom, where protons and neutrons are bound together

Electron
Negatively charged part of an atom that orbits the nucleus

Proton
Positively charged part of an atom that is located in the nucleus

Neutron
Neutrally charged part of the atom that is located in the nucleus

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

Isotope
Atoms of the same element that differ in the number of neutrons they contain.

Mass Number
The sum of the number of protons and neutrons in nucleus of an atom

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

Valence electrons
Electrons that are available to form bonds

Ionic bond
Formed when one or more electrons are transferred from one atom to another.

Covalent bond
When electrons are shared between atoms.

Molecule
Smallest unit of most compounds. Structure that results when atoms are joined together by covalent bonds.

Van der Walls force
Slight attractions between oppositely charged regions of nearby molecules.

Polarity
When there is an uneven distribution of electrons between the atoms in a molecule

Hydrogen bonds
The attraction between the hydrogen atom on one water molecule and the oxygen atom on another. Weaker than ionic or covalent bonds, but is responsible for cohesion

Cohesion
Attraction between molecules of same substance

Adhesion
Attraction between molecules in different substances

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

Solution
When all the components are evenly distributed throughout the solution

Solute
The substance that is dissolved

Solvent
The substance in which the solute dissolves

Suspension
Non-dissolved material in a liquid

pH scale
Scale that indicates the concentration of H+ ions in solution. Lower is acidic, higher is basic

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

Macromolecule
Large molecules that are made up of many other smaller molecules

Monomers
Single unit of polymer

Polymer
Made up of monomers

Carbohydrate
Made of Carbon, Hydrogen, and Oxygen atoms in a ratio of 1:2:1. Used for main source of energy and plants and some animals also use carbohydrates for structural purposes. Monomer-monosaccharaides. Polymer-polysaccharides.

Lipids
Made of Carbon and Hydrogen atoms. Used to store energy, make up membranes, and waterproof coverings. Formed from Glycerol molecule combines with compounds called fatty acids. If no double bonds—saturated (butter), if one double bond—unsaturated (olive oil), if multiple double bonds—polyunsaturated (Cooking oils). Monomer—Glycerol and fatty acids

Nucleic acid
Contains hydrogen, oxygen, nitrogen, carbon, and phosphorus. They store and transmit hereditary/genetic information. Two kinds—RNA and DNA. Monomer—nucleotides. Consists of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Protein
Contain Nitrogen, Carbon, Hydrogen, and Oxygen. They control rate of reaction, regulate cell processes, form bones and muscles, or help fight disease. Monomer—amino acids

Chemical reaction
A process that changes one set of chemicals into another set of chemicals

Reactant
Elements or compounds that enter a chemical reaction

Product
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

Enzyme
Proteins that act as biological catalysts

Enzyme-substrate complex
The site where reactants can be brought together to react. Site reduces energy needed for reaction.

Substrate
The reactants of enzyme-catalyzed reactions

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