AP BIOLOGY - UNIT 1

Matter

Anything that has mass and takes up space

Element

A substance that cannot be broken down into any other substances by chemical reactions

Compound

a thing that is composed of two or more separate elements combined in a fixed ratio

essential elements

elements that an organism needs to live a healthy life and reproduce

trace elements

required by an organism in only minute quantities

Atom

the smallest unit of matter that still retains the properties of an element

Neutrons

the particles of the nucleus that have no charge

Protons

positively charged subatomic particles

Electrons

negatively charged subatomic particles. Mass is 1\2,000 of a proton or neutron

Atomic nucleus

The dense, positively charged center of every atom

Dalton

A measure of mass for atoms and subatomic particles; the same as the atomic mass unit, or amu. 17x10^-24

Atomic number

the number of protons in the nucleus of an atom(same as the number of electrons.)

mass number

the sum of the number of neutrons and protons in an atomic nucleus

atomic mass

total mass of an atom, usually equal to the mass number

isotopes

Atoms of the same element with different numbers of neutrons

radioactive isotope

An isotope whose nucleus decays spontaneously, giving off particles and energy.

energy

the capacity to cause change; the ability to do work

potential energy

stored energy that results from the position or shape of an object

electron shells

An energy level representing the distance of an electron from the nucleus of an atom. The further away from the nucleus, the more energy.

valence shell

the outermost electron shell; the number of electrons in that shell determine the chemical behavior of an atom.

chemical bonds

the attractive forces that hold atoms together

Covalent bond

the sharing of a pair of valence electrons by two atoms; strong interaction.

Molecule

two or more atoms held together by covalent bonds

single bond

A pair of shared electrons

An atom's valence

1. an atom's bonding capacity corresponding to the number of covalent bonds the atom can form

2. usually equals the number of unpaired electrons required to complete the atom's most outermost (valence) shell

double bond

A chemical bond formed when atoms share two pairs of electrons

Electronegativity

the ability of an atom to attract electrons when the atom is in a compound

nonpolar covalent bond

a covalent bond in which the electrons are shared equally by the two atoms

polar covalent bond

A covalent bond in which electrons are not shared equally

ionic bond

Formed when one or more electrons are transferred from one atom to another, making one atom positively charge and the other negatively charged, causing them to attract; strong bond

Ion

A charged atom. Cation is positive. Anion is Positive

Salts

compounds formed by ionic bonds

hydrogen bond

Attraction between a slightly positive hydrogen atom and a slightly negative atom (noncovalent). Weak bond

Van der Waals interactions

attractions between molecules that are close together as a result of these charges

chemical reactions

the making and breaking of chemical bonds, leading to changes in the composition of matter

reactants and products

number of atoms stays the same in both

chemical equilibrium

In a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time.

Water

polar molecule( overall charge is unevenly distributed)

Cohesion

an attraction between molecules of the same substance

Adhesion

An attraction between molecules of different substances

surface tension

A measure of how difficult it is to stretch or break the surface of a liquid. Water has a high one

kinetic energy

the energy an object has due to its motion(thermal energy-dependant on size)

Temperature

A measure of how hot (or cold) something is; specifically, a measure of the average kinetic energy of the particles in an object.

Calorie

Amount of energy needed to raise temperature 1 gram of water 1 degree C

Joule

unit of energy. =0.239 calories

specific heat

the amount of heat that must be absorbed or lost for 1 gram of that substance to change its temperature by 1 C. Water has a high one.

heat of vaporization

the quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state

evaporative cooling

The process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid to the gaseous state.

solution

a liquid that is a completely homogeneous mixture of two or more substances

Solvent

the dissolving agent of a solution

Solute

A substance that is dissolved in a solution.

aqueous solution

a solution in which water is the solvent

hydration shell

the sphere of water molecules around each dissolved ion

Hydrophilic

Having an affinity for water.

Hydrophobic

substances that repel water

molecular mass

The sum of the masses of all the atoms in a molecule

Molarity

the number of moles of solute per liter of solution

hydrogen ion

a single proton with a charge of 1+

hydroxide ion

a water molecule that has lost a proton; OH-

hydronium ion

the positive ion formed when a water molecule gains a hydrogen ion

Acid

A substance that increases the hydrogen ion concentration of a solution.

Base

A substance that decreases the hydrogen ion concentration in a solution, sometimes by forming hydroxide ions

pH

declines as hydrogen ions/hydronium ions increase

buffer

a substance that minimizes changes in the concentrations of H+ and OH- in a solution

organic compound

Compounds that contain carbon

macromolecules

large polymers

atom's valence

the number of covalent bonds it can form

hydrocarbons

Compounds composed of only carbon and hydrogen. Are hydrophobic and can release large amounts of energy.

Functional groups

the components of organic molecules that are most commonly involved in chemical reactions. Seven most important are hydroxyl (-OH), carbonyl (//C=O), carboxyl(-COOH), amino(-NH2), sulfhydryl(-SH), phosphate(-OPO3^2-), and methyl(-CH3).

ATP

(adenosine triphosphate) main energy source that cells use for most of their work. Made of three phosphate groups, ribose, and adenine.

polymer

A long molecule consisting of many similar or identical monomers linked together by covalent bonds

Enzymes

Catalysts for chemical reactions in living things

dehydration synthesis

A chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule.

Hydrolysis

Breaking down complex molecules by the chemical addition of water

Carbohydrates

sugars and polymers of sugars. Remember that sugars have a carbonyl group and multiple hydroxyl groups.

Monosaccharides

Single sugar molecules. Glucose is the most important one

disaccharide

two monosaccharides joined by a glycosidic linkage

glycosidic linkage

a covalent bond formed between 2 monosaccharides by a dehydration reaction

starch

storage form of glucose in plants

Glycogen

An extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch.

Cellulose

a structural polysaccharide of plant cell walls, consisting of glucose monomers joined by beta glycosidic linkages

Chitin

A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods.

Lipids

Energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen. HYDROPHOBIC

fat

constructed from glycerol and fatty acids

Triacylglycerides

three fatty acids linked to one glycerol molecule

saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that can attach to the carbon skeleton.

unsaturated fatty acid

A fatty acid possessing one or more double bonds between the carbons in the hydrocarbon tail. Such bonding reduces the number of hydrogen atoms attached to the carbon skeleton.

Phospholipid

a lipid that contains phosphorus and that is a structural component in cell membranes

Steroids

lipids characterized by a carbon skeleton consisting of four fused rings

catalysts

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

polypeptides

polymers of amino acids

Protein

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

amino acid

Organic molecule composed of an amino group and an acid group

peptide bond

covalent bond formed between amino acids

primary structure of protein

sequence of amino acids

secondary structure of protein

protein structure is formed by folding and twisting of amino acid chain

tertiary structure of protein

Defined by the hydrophilic and hydrophobic interactions between R groups of amino acid chains.

quaternary structure

The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits.

Denaturation

In proteins, a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. In DNA, the separation of the two strands of the double helix.