Chapter 2

Chemical Basis of Lifecontinued…

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Atomic Structure:Atomic Structure:ProtonsProtons

NucleusNucleus+ charge+ charge1 AMU (atomic mass unit ~ 1.67 1 AMU (atomic mass unit ~ 1.67 ×× 1010−−2424 g )g )

NeutronsNeutronsNucleusNucleus0 charge0 charge~ 1 AMU (1AMU + ~ 9.11 ~ 1 AMU (1AMU + ~ 9.11 ×× 1010--2828 g)g)

ElectronsElectronsOrbit nucleusOrbit nucleus-- chargecharge~ 1~ 1⁄⁄1836 AMU (~ 9.11 1836 AMU (~ 9.11 ×× 1010--2828 g)g)

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An electrically neutral atom has An electrically neutral atom has equal numbers of protons and electrons.equal numbers of protons and electrons.

The number of protons denotes theThe number of protons denotes the atomic atomic numbernumber of an elementof an element

The number of protons plus the average The number of protons plus the average number of neutrons equals the number of neutrons equals the atomic weight.atomic weight.

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Periodic TablePeriodic Table

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HydrogenHydrogen

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OxygenOxygen

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CarbonCarbon

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Bonding of Atoms: Bonding of Atoms: 1. Atoms form bonds by gaining, losing, 1. Atoms form bonds by gaining, losing, or sharing electrons.or sharing electrons.2. Electrons are found in shells around 2. Electrons are found in shells around the nucleus.the nucleus.

a. first energy shell holds a maximum a. first energy shell holds a maximum of of twotwo electronselectronsb. other energy shells each hold a b. other energy shells each hold a maximum of maximum of eighteight electronselectrons

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3. Atoms with incompletely filled outer 3. Atoms with incompletely filled outer shells tend to be reactive to form shells tend to be reactive to form stable outer shells of 8.stable outer shells of 8.

4. When atoms gain or lose electrons, 4. When atoms gain or lose electrons, they become they become ionsions with a charge. with a charge.

5. Oppositely5. Oppositely--charged ions attract each charged ions attract each other and form an other and form an ionic bondionic bond..

1010Ionic Flash

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Covalent Flash

Covalent bondCovalent bondatoms share electrons to become stableatoms share electrons to become stablewith filled outer shells.with filled outer shells.

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D.D. Molecules and Compounds:Molecules and Compounds:

Molecule = two or more atoms combinedMolecule = two or more atoms combined

Compound = two or more atoms of different Compound = two or more atoms of different elements combinedelements combined

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Formulas:Formulas:1. 1. A molecular formula represents the numbers A molecular formula represents the numbers

and types of atoms in and types of atoms in a molecule. a molecule. Ex: Glucose = CEx: Glucose = C66HH1212OO66

2. 2. Various representations, called structural Various representations, called structural formulas, can be used to illustrate formulas, can be used to illustrate molecules.molecules.Ex: Glucose =Ex: Glucose =

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Chemical Reactions: Chemical Reactions: 1. Bonds are formed or broken between 1. Bonds are formed or broken between

atoms, ions, or molecules.atoms, ions, or molecules.2. 2. Reactants Reactants transformed totransformed to ProductsProducts..3. Synthesis3. Synthesis A + B A + B →→ CC4. Decomposition4. Decomposition A A →→ B + CB + C5. Exchange reactions5. Exchange reactions AB + C AB + C →→ A + BCA + BC6. Reversible reactions6. Reversible reactions A + B A + B ↔↔ CC

7. Catalysts7. Catalysts speed chemical reactions.speed chemical reactions.

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Acids and Bases: Acids and Bases: 1. Substances that release ions in water 1. Substances that release ions in water

are called electrolytes.are called electrolytes.

2. Electrolytes that release hydrogen 2. Electrolytes that release hydrogen ions in water are called acids.ions in water are called acids.

3. Electrolytes that release ions that 3. Electrolytes that release ions that combine with hydrogen ions in water combine with hydrogen ions in water are called bases.are called bases.

4. pH = concentration of hydrogen ions [HpH = concentration of hydrogen ions [H++] ] in solutionin solution

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5. pH of 7 = neutral solution 5. pH of 7 = neutral solution equal numbers of Hequal numbers of H++ and OHand OH-- ions.ions.

6. pH of 0 to <7 = more H+ and so acid6. pH of 0 to <7 = more H+ and so acid

7. pH of <7 to 14 = less H+ and so basic7. pH of <7 to 14 = less H+ and so basic

8. each whole number increase in pH = 10x 8. each whole number increase in pH = 10x increase in concentration of H+ ionsincrease in concentration of H+ ions

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ΞΞ Chemical Constituents of Cells:Chemical Constituents of Cells:

InorganicInorganicWaterWater HH22OO

Most abundant compound in cellsMost abundant compound in cells2/3 of adult weight2/3 of adult weightPolar structure allows formation of H bondsPolar structure allows formation of H bondsUniversal solvent Universal solvent High heat capacityHigh heat capacityCarries O2, sugars, and waste Carries O2, sugars, and waste Can absorb and transport heatCan absorb and transport heat

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Oxygen Oxygen OO22

Driver of cellular metabolismDriver of cellular metabolismReleases energy from nutrientsReleases energy from nutrients

Carbon DioxideCarbon Dioxide COCO22

Metabolic waste product Metabolic waste product

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Inorganic SaltsInorganic SaltsPlay important roles in metabolic processes. Play important roles in metabolic processes. SodiumSodium NaNa++

ChlorideChloride ClCl--PotassiumPotassium KK++

CalciumCalcium CaCa2+2+

MagnesiumMagnesium MgMg2+2+

PhosphatePhosphate POPO4433--

CarbonateCarbonate COCO3322--

BicarbonateBicarbonate HCOHCO33--

Sulfate.Sulfate. SOSO4422--

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Organic Substances:Organic Substances:

CarbohydratesCarbohydratesprovide energy for cellular activities provide energy for cellular activities C, H, OC, H, O general formula Cgeneral formula C6x6xHH12x12xOO6x6x

monosaccharides = simple sugars = simple sugars disaccharides = two = two monosaccharidesmonosaccharidespolysaccharides built of many sugarsbuilt of many sugars

CopyrightCopyright©©The McGrawThe McGraw--Hill Companies, Inc. Permission required for reproduction or disHill Companies, Inc. Permission required for reproduction or display.play.

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Lipids: includeFats

energy store energy store Glycerol +3 fatty acidsGlycerol +3 fatty acidsLess O2 than carbohydratesLess O2 than carbohydrates

PhospholipidsGlycerol +2 fatty acids +1 phosphate groupGlycerol +2 fatty acids +1 phosphate groupimportant in cell structures.important in cell structures.

SteroidsComplex ring structuresComplex ring structuresEx/ cholesterolEx/ cholesterol

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Proteins:Proteins:C, O, H, NC, O, H, NAmino AcidsAmino Acids

carboxyl groupcarboxyl groupamino group amino group R group.R group.

Serve asStructural materialsStructural materialsEnergy sourcesEnergy sourcesHormonesHormonesReceptors on cell membranesReceptors on cell membranesAntibodiesAntibodiesEnzymesEnzymes

Protein Denaturation Flash

Complex shapes held Complex shapes held together by H bonds.together by H bonds.

Protein shapes determine Protein shapes determine function and can be altered function and can be altered (denatured) by pH, (denatured) by pH, temperature, radiation, or temperature, radiation, or chemical forcing.chemical forcing.

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Some Latin to remember for the lab Some Latin to remember for the lab (and for later)(and for later)

--oseose = sugar= sugar