AP Biology Notes Unit 1

Essential Elements

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

Trace Elements

Elements required by organisms in only minute quantitites

Covalent Bond

The sharing of a pair of valence electrons by two atoms

Electronegativity

The attraction of a particular atom for the electrons of a covalent bond

Polar Covalent Bond

A covalent bond between atoms that differ in electronegativity

Polar Molecule

A molecule with an uneven distribution of charges in different regions of the molecule

Cohesion

The linking together of like molecules, often by hydrogen bonding

Adhesion

the clinging of one substance to another

Surface Tension

A measure of how difficult it is to stretch

How does water moderate air temperature?

By absorbing heat from air that is warmer and releasing the stored heat to air that is cooler

Kinetic Energy

The energy of motion

Temperature

The average kinetic energy of molecules

Specific Heat

The amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1 degree Celsius

Evaporation

The transformation from liquid to gas by molecules moving fast enough to overcome intermolecular attractions

Heat of Vaporization

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

Evaporative Cooling

The surface of an object becomes cooler during evaporation as the molecules with the greatest kinetic energy change phases

Solution

Completely homogeneous mixture of two or more substances

Solvent

Dissolving agent of a solution

Solute

The substance that is dissolved

Hydrophilic

A substance that has an affinity for water

What types of molecules are hydrophilic?

Ionic and Polar

What types of molecules are hydrophobic?

non-polar and nonionic

Molecular Mass

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

Molarity

Number of moles of solute per liter of solution

Hydrogen Ion

A single proton with a charge of 1+

Hydroxide Ion

OH-

Hydronium Ion

H3O+

Acid

A substance that increases the hydrogen ion concentration of a solution

Base

A substance that reduces the hydrogen ion concentration of a solution

pH

The negative logarithm of the hydrogen ion concentration

Buffer

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

Hydrocarbons

Organic Molecules consisting of only carbon and hydrogen

Are carbon to hydrogen linkages polar or nonpolar?

relatively non-polar

Isomers

Compounds that have the same numbers of atoms of the same elements but different structures and hence different properties

Structural Isomers

Differ in the covalent arrangements of their atoms

Cis-trans isomers

carbons have covalent bonds to the same atoms, but these atoms differ in their spatial arrangements due to the inflexibility of double bonds

Enantiomers

Isomers that are mirror images of each other adn that differ due to the presence of an asymmetric carbon

Functional Groups

a specific configuration of atoms commonly attached to the carbon skeletons of organic molecules that affect molecular function by being directly involved in chemical reactions

Macromolecules

A giant molecule formed by the joining of smaller molecules (usually by dehydration reaction)

Polymer

A long molecule consisting of many similar or identical building blocks linked by covalent bonds

Monomers

The repeating units that serve as the building blocks of a polymer (are smaller molecules)

Enzymes

Specialized macromolecules that speed up chemical reactions

Dehydration Reaction

A reaction in which two molecules are covalently bonded to each other, with the loss of water molecule(s)

How are monomers connected?

By dehydration reaction (one monomer provides a hydroxyl group and the other provides a hydrogen ion)

Hydrolysis

A chemical reaction that breaks bonds between two molecules by the addition of waterH

How are polymers dissassembled to monomers?

Hydrolysis

Monosaccharides

Simple sugars and the simplest form of carbohydrates

Disaccharides

Double sugars consisting of two monosaccharides joined by a covalent bond (glycosidic linkage)

Polysaccharides

Polymers composed of many sugar building blocks

What is the most common monosaccharide?

glucose

Glycosidic Linkage

A covalent bond formed between two monosaccharides by a dehydration reaction

Starch

A polymer of glucose monomers

Glycogen

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

What is the animal equivalent of starch?

glycogen

What releases sugar from starch/glycogen when demand for sugar increases?

Hydrolysis

Microfibrils

units of parallel cellulose molecules held together by hydrogen-bonds of hydroxyls

Chitin

A structural polysaccharide used by arthropods to build their exoskeletons

What material do organisms commonly use to build strong materials?

Structural polysaccharides

What is the one class of large biological molecules that does not include true polymers?

Lipids

Do lipids mix well with water?

No, they mix poorly, if at all, with water

Name 3 common examples of lipids

Fats, phospholipids, and steroids

Ester Linkage

A bond between a hydroxyl and carboxyl group

Tricylglycerol

A fat consisting of 3 fatty acids linked to 1 glycerol molecule by an Ester linkage

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 are attached to the carbon skeleton (SATURATED WITH HYDROGEN)

Unsaturated Fatty Acid

A fatty acid that has one or more double bonds between carbons in the hydrocarbon tail (reduces amount of hydrogen attached to carbon skeleton)

Are Unsaturated Fatty Acids liquid or solid at room temperature?

Liquid - double bonds cause bending in the carbon skeleton

What is the major function of fats?

energy storage

Are fats or polysaccharides a more compact reservoir of fuel?

Fats

Phospholipids

Two fatty acids attached to a glycerol (make up cell membranes)

Describe the behavior towards water of each end of a phospholipid

Hydrocarbon tail is hydrophobic, phosphate group and its attachments form a hydrophilic head

Phospholipid Bilayer

A boundary between the cell and its external environment formed by phospholipids in an attempt to shield their hydrophobic portions from water

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings

Cholesterol

A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other important steroids (such as hormones)

Enzymatic Proteins

Proteins that regulate metabolism by acting as catalysts

Proteins

Unbranched polymers constructed from the same set of 20 amino acids

Polypeptides

A polymer of many amino acids linked together by peptide bonds

Protein

A biologically functional molecule that consists of one or more polypeptides

Amino Acid

An organic molecule possessing both an amino group and a carboxyl group