Chapter 2

MatterAny substance that has mass and takes up spaceComposed of 1 or more elementsFound in 1 of 3 states

Gas – no definite shape or volumeLiquid – shape conforms to container Solid – definite shape

ElementsSubstances that can’t be broken down

by ordinary chemical processes92 occur naturally on Earth

About 25 are essential to life96% of human body, as well as other living

organisms, from 4 elements (CHON)

Composed of atoms2+ of same atoms is a molecule (O2)2+ of different atoms is a compound (NaCl, H2O)

Metal + poisonous gas = edible product Gas + gas = liquid

Oxygen 61.0%Carbon 23.0Hydrogen 10.0Nitrogen 2.6Calcium 1.4Phosphorus 1.1Potassium 0.2Sulfur 0.2

Human

96%

AtomsSmallest particles that retain the

properties of an elementMade up of subatomic particles:

Protons (+) in nucleusElectrons (-) orbits nucleusNeutrons (no charge) in nucleus

Protons and neutronsMass of about 1 dalton (atomic mass unit,

amu)Electrons

Mass is negligible (1/2000 amu)

Reading A Periodic TableElements differ depending on the number

of subatomic particlesAtomic symbol

1st letter or 2 (usually)Atomic number

Determined by number of protons Neutral atoms contain equal # of electrons

Element specificMass number

Determined by number of protons + neutrons

Atomic weight: average of relative weights of all isotopes, versions of the element

The Periodic TableMost Common Elements

in Living Organisms

Chemical BondsEnergy relationship between electrons

Energy is the capacity to do work, cause change, or move matter Kinetic: energy of motion Potential: energy due to location or structure; capability

Electrons repel one another (magnets), but attracted to protons (opposites attract)

Determine chemical properties, reactivity, of atomsOrbitals are key

Closer to the nucleus = lower energy and filled firstOctet rule: hold up to 8 electrons (not 1st = 2)Outermost is valence shell

Chemical reactions are making and breaking bonds

Inert versus reactive elementsValence electrons

Ionic BondsOne atom loses electron(s) to become _____ charge?Another atom gains these electrons to become _____

charge?Charge difference attracts the two ions to each other

Clinically called electrolytesVery weak bondE.g. Salts cation anion

Covalent BondsAtoms share a pair(s) of electrons to fill valence

shellForm single, double, or triple covalent bond, based

on number of electrons sharedStrong bonds

What’s Mine is Yours or Just MineNonpolar molecules Polar Molecules

Electrons shared equallyExample: carbon

dioxide(CO2)

Electrons spend more time near the nucleus with the most protons (electronegativity)

Example: water (H20)

Hydrogen BondsSpecial case of covalent bondsAttractions between molecules

Polar hydrogen (slightly ‘+’ charge) attracted to another polar molecule (slightly ‘-’ charge)

Hold large molecules in a specific 3D shape

Chemical ReactionsChemical equation: reactant(s) + reactant(s) =

product(s)May be reversibleMove to equilibrium

TypesSynthesis: (A + B AB) usually anabolic and endergonicDecomposition: (AB A + B) usually catabolic and

exergonicExchange: (AB + CD AD + BC) may or may not be

endergonic/exergonicRedox: may gain or lose electrons

Oxidized – loses electrons (LEO) Reduced – gains electrons (GER)

Affected by temperature, concentration, catalysts, etc.

Biologically Important Compounds Inorganics lack carbon (generally)

E.g. salts, water, acids, and bases Organics contain carbon, are covalently

bonded, and generally largeE.g. carbohydrates, lipids, proteins, and

nucleic acids

Properties of WaterTemperature-stabilizing effects

Absorbs and releases large amounts of heat w/o significant change

Sun, wind, muscle activityHigh heat of evaporation

Absorption of heat breaks bonds; liquid gasSweating

Polar moleculeHydrophobic and hydrophilic

Solvent/solute relationship Blood circulation, waste disposal, and cleaning

ReactivityHydrolysis and dehydration reactions

ElectrolytesIons able to conduct electrical

currentKidneys regulateSalts contain ions other than H+ or

OH-

E.g. NaCl, CaCO3, and calcium phosphates

Acids are hydrogen ion (H+) donorsConcentration determines acidity of

a solutionE.g. pH < 7; HCl, H2CO3

Bases are hydrogen acceptorsForm water upon disassociationE.g. pH > 7; Mg(OH) 2, HCO3

-, and NH3

Buffers release H + with increasing pH and accept H + when decreasingH2CO3 HCO3

- + H+

Building Organic MoleculesMonomers: small repeating units

Universal, similar in all forms of lifePolymers: chains of monomers, functional

components of cells (macromolecules)DNA is composed of 4 monomers (nucleotides)

Variation based on arrangementProteins from 20 different amino acids (AA’s)

Variation distinguishes within and between species

Making and Breaking PolymersDehydration reaction Hydrolysis reactionLinks monomersLoss of water for each

monomer addedForms a covalent bond

Breaks polymersAddition of water for

each broken bond

1 42

21

3

3 4

1

2

2 3

3

4

41

CarbohydratesGeneral (CH2O)n ratio, end in ‘ose’Fuel source for cellsGlycosidic bonds

Dehydration vs. hydrolysisMonosaccharides (simple)

Pentoses: ribose and deoxyriboseHexoses: glucose, fructose, & lactose

(energy production)Disaccharides (simple)

Maltose, lactose (glu + gal), & sucrose (glu + fru)

Polysaccharides (complex)Glycogen (animal storage)Starch (plant storage)

Lipids Composed of fatty acids (long carbon chains) and a glycerol (3

carbons) Triglycerides

3 FA’s Most usable form of energy Fats (animal) and oils (plants) Saturated or unsaturated (mono- or poly-)

Phospholipids 2 FA’s and a phosphate group Amphipathic molecule

Cell membranes Steroids

Hydrocarbon rings Cholesterol and sex hormones

Eicosanoids In all cell membranes Prostaglandins role in blood clotting,

inflammation, and labor contractions

ProteinsChains of amino acids joined by peptide bonds

20 different types (alphabet)Peptide, polypeptides, and proteins (words) are all slightly

differentStructural levels

Primary (1°) – sequence of amino acidsSecondary (2°) – primary level folds to form alpha (α) – helixes

and beta (β) - pleated sheetsTertiary (3°) – folding of secondary structures on each otherQuaternary (4°) – 2+ polypeptides interact to form a protein

Denaturation destroys structure which alters or inhibits functionChanges in pH and temperatureReversible or permanent depending on extend of change

(fevers)

Protein TypesFibrous (structural proteins)

Building materials of the body Keratin, elastin, and collagen

MovementGlobular (functional proteins)

Enzymes TransportImmunity

EnzymesGlobular proteins acting as catalysts to speed a reaction

Lower energy of activation (EA)

End in ‘ase’ and named for substrateMechanism of enzyme action:

Enzyme binds substrate at its active site on the enzyme.

Enzyme-substrate complex undergoes an internal rearrangement that forms a product.

Product released and now catalyzes another reaction

Nucleic AcidsDNA and RNA Composed of nucleotides with

3 componentsPentose sugarPhosphate group (PO4)Nitrogenous base form

complementray pairs Purines (2 rings): adenine (A)

and guanine (G) Pyrimidines (1 ring): thymine (T),

cytosine (C), and uracil (U)

How DNA and RNA DifferDNA

(deoxyribonucleic acid)

RNA(ribonucleic acid)

Directs protein synthesis; replicates self; genetic material

Sugar is deoxyriboseHas –H

Bases are A,C, G, and TDouble-stranded helixOnly in nucleus1 type

Carries out protein synthesis

Sugar is riboseHas -OH

Bases are A, C, G, and USingle-strandedNot confined to nucleus3 major types

Adenosine Triphosphate (ATP)RNA nucleotide with 3

phosphate groupsStores energy from

break down of glucoseTransfers phosphate

groups to release energy, phosphorylation

Controls energy release