AP Biology Unit 1

Matter

Matter

Anything that takes up space and has mass (Rocks, metals, oils, gases, organisms)

Element

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

Compound

A substance consisting of two or more different elements combined in a fixed ratio (H2O, NaCl)

Atomic number

Number of protons

Atomic Mass

Number of protons plus neutrons averaged over all isotopes

Octet rule

Elements will gain, lose, or share electrons to complete their valence shell and become stable (like noble gases)

Chemical Bonds

An attraction between two atoms, resulting from the sharing or transferring of valence electrons.

Electronegativity

The measure of an atoms ability to attract electrons itself

Covalent bonds

When two or more atoms share electrons (usually between two nonmetals)

Non polar covalent

Electrons are shared equally between two atoms

Polar covalent

electrons are not shared equally between 2 atoms

Ionic Bonds

The attraction between oppositely charged atoms (ions).

Cation

Positively charged ion

Anion

Negatively charged ion

Hydrogen Bonds

The partially positive hydrogen atom in one polar covalent molecule will be attracted to an electronegative atom in another polar covalent molecule

Intermolecular bond

Bond that forms between molecules

Polarity

Polar bonds created by the unequal sharing of electrons between oxygen and hydrogen within the molecule of water

Cohesion

Attraction of molecules for other molecules of the same kind (H20, to H20)

Adhesion

The tendency of two or more different molecules to bond with each other

Capillary action

The upward movement of water due to the forces of cohesion, adhesion, and surface tension (adhesion is greater than cohesion).

High specific heat

H2O resists changes in temperature due to Hydrogen bonds

Density

As water solidifies it expands and becomes less dense

Solvent

Dissolving agent in a solution

pH

A numerical measure of the acidity or alkalinity of a solution, usually measured on a scale of 0 to 14

Acid

Substance that releases hydrogen ions (H+) when dissolved in water (pH less than 7).

Base

substance that accepts H+ OR releases hydroxide ions (OH-) when dissolved in water (pH of greater than 7).

Buffer

A solution that resists changes in pH when an acid or base is added (helps maintain pH stability in biological systems).

Evaporative cooling

As water molecules evaporate, the surface they evaporate from gets cooler

Organic chemistry

The study of compounds with covalently bonded carbon

Organic compounds

compounds that contain carbon and hydrogen

Functional groups

Chemical groups attached to the carbon skeleton that participate in chemical reactions

Polymers

Chain like macromolecules of similar or identical repeating units that are covalently bonded together.

Monomers

The repeating units that make up polymers

Dehydration reaction

Bonds two monomers with the loss of H2O.

Hydrolysis

Breaks the bonds in a polymer by adding H2O.

Hydrocarbons

Organic molecules consisting only of carbon and hydrogen

What are carbohydrates?

Includes sugars and polymers of sugars; contain a carbonyl group and many hydroxyl groups; comprised of C, H, and O.

Monosaccharides

Simple sugars with molecular formulas as multiples of CH₂O; most common is glucose; serve as nutrients and fuel for cells, used in cellular respiration, and as building blocks for di- and polysaccharides.

Disaccharides

Two monosaccharides joined by covalent bonds; most common is sucrose, composed of glucose and fructose; plants transfer carbohydrates in the form of sucrose.

Polysaccharides

Polymers with many sugars joined via dehydration reactions; storage polysaccharides include starch (plants) and glycogen (animals); structural polysaccharides include cellulose (plant cell walls) and chitin (exoskeletons of arthropods).

Lipids

A class of molecules that do not include true polymers; generally small in size; nonpolar and hydrophobic.

Types of lipids

Fats, phospholipids, steroids.

Fats

Composed of glycerol and fatty acids; glycerol is an alcohol; fatty acids are long carbon chains with a carboxyl group; joined by ester linkage; classified as saturated or unsaturated.

Saturated fatty acids

No double bonds between carbons in the chain; "saturated" with hydrogen.

Unsaturated fatty acids

Contains one or more double bonds between carbons.

Phospholipids

Major component of cell membranes; consist of two fatty acids, glycerol, and a phosphate; form a bilayer in water with hydrophobic tails and a hydrophilic head.

Steroids

Lipids with four fused rings; unique groups attached to these rings determine the type of steroid; example: testosterone.