The Chemistry of LifeThe Chemistry of Life
Chapter 2Chapter 2
AtomsAtoms
““Unable to Unable to be cut”be cut”
Element-pure substance composed of only one Element-pure substance composed of only one type of atomtype of atom
Isotope-atoms of same element containing Isotope-atoms of same element containing different numbers of neutronsdifferent numbers of neutrons
NucleusNucleus
Protons- +Protons- + Mass = 1Mass = 1 The sum of Protons The sum of Protons
and Neutrons is the and Neutrons is the mass numbermass number
Neutrons- 0 Neutrons- 0 (neutral)(neutral)
Mass = 1Mass = 1
ElectronElectron
Charge = -1Charge = -1 Mass = 1/1840Mass = 1/1840 Attracted to Attracted to
positively charged positively charged nucleus but their nucleus but their constant motion constant motion prevents them prevents them from entering the from entering the nucleusnucleus
Because atoms Because atoms have equal have equal numbers of numbers of electrons and electrons and protons atoms are protons atoms are neutral.neutral.
IsotopesIsotopes
Atoms of an element that have Atoms of an element that have differing numbers of neutronsdiffering numbers of neutrons
Because they have the same number Because they have the same number of electrons, all isotopes of an of electrons, all isotopes of an element have the same chemical element have the same chemical propertiesproperties
SimpleSimple
elements
CompoundCompound
Chemical compounds
Chemical CompoundsChemical Compounds
A substance formed A substance formed by the chemical by the chemical combination of two or combination of two or more elementsmore elements
Hydrogen gas + Hydrogen gas + Hydrogen gasHydrogen gas + + Oxygen gas =Oxygen gas =
HH22OO
Chemical CompoundsChemical Compounds
Physical and chemical properties of a Physical and chemical properties of a compound can be very different from compound can be very different from the elements that make itthe elements that make it
Sodium-a silver-colored metal that can Sodium-a silver-colored metal that can be cut with a knifebe cut with a knife
Chlorine-a poisonous, greenish gas Chlorine-a poisonous, greenish gas that was used to kill soldiers in WWIthat was used to kill soldiers in WWI
Chemical Bonds-The GlueChemical Bonds-The Glue
Ionic Bonds-Ionic Bonds-transferring transferring electrons from one electrons from one atom to anotheratom to another
Covalent BondingCovalent Bonding
Covalent Bonds form when electrons are Covalent Bonds form when electrons are shared between atoms.shared between atoms.
Van der Waals ForcesVan der Waals Forces
Minor attractions Minor attractions between moleculesbetween molecules
Involves opposite Involves opposite chargescharges
WaterWater
O H+
++ +
+
+++
++
- -
Hydrogen BondsHydrogen Bonds
Cohesion-an Cohesion-an attraction between attraction between molecules of the molecules of the same substancesame substance
Allows water to Allows water to form droplets on form droplets on smooth surfacessmooth surfaces
Hydrogen BondsHydrogen Bonds
Water molecules attract Water molecules attract each other because of each other because of partial chargespartial charges
Polar molecule charges are Polar molecule charges are written in ( )written in ( )
The ability of The ability of water to form water to form multiple bonds multiple bonds gives it important gives it important characteristicscharacteristics
A single water A single water molecule may molecule may form up to four H-form up to four H-bondsbonds
WaterWater
Cohesion-attraction to itselfCohesion-attraction to itself Adhesion-attraction to other Adhesion-attraction to other
substancessubstances Capillary action-moves water Capillary action-moves water
against gravity in tiny tubesagainst gravity in tiny tubes
Surface TensionSurface Tension
Cohesion
Mixing it UpMixing it Up
Mixture- two or Mixture- two or more elements or more elements or compounds that are compounds that are physically mixed physically mixed together but not together but not chemically joined.chemically joined.
Ex. Sugar and sand Ex. Sugar and sand mixed togethermixed together
Suspension-Suspension-mixtures of water mixtures of water and un-dissolved and un-dissolved particlesparticles
Solution: all Solution: all components are components are evenly distributedevenly distributed
Ex. Salt waterEx. Salt water SoluteSolute SolventSolvent
pHpH
HH22O HO H++ + OH + OH--
Water Hydrogen Ion + Water Hydrogen Ion + Hydroxide IonHydroxide Ion
AcidsAcids
Acid- any compound that forms HAcid- any compound that forms H++ in in solutionsolution Have higher concentrations of Hydrogen Have higher concentrations of Hydrogen
ions than pure waterions than pure water Have pH values BELOW 7Have pH values BELOW 7 7
ACIDS
BasesBases
Compounds that produce Compounds that produce OHOH-- (hydroxide) ions in (hydroxide) ions in solution.solution.
Basic solutions contain Basic solutions contain lower concentrations of lower concentrations of HH++ ions than pure water ions than pure water and have a pH value and have a pH value greater than 7.greater than 7.
Bases
7
Common SolutionsCommon Solutions
AcidicAcidic Tomato JuiceTomato Juice Lemon JuiceLemon Juice SodaSoda
BasicBasic AmmoniaAmmonia BleachBleach SoapSoap
BufferBuffer
pH of Human body is between 6.5 pH of Human body is between 6.5 and 7.5and 7.5
Buffers- weak acids or bases that can Buffers- weak acids or bases that can react with strong acids or bases to react with strong acids or bases to prevent sharp, sudden changes in pHprevent sharp, sudden changes in pH
Carbon CompoundsCarbon Compounds
Organic-contains Organic-contains carboncarbon
Four groups of Four groups of organic compounds organic compounds making up living making up living things arethings are CarbohydratesCarbohydrates LipidsLipids Nucleic AcidsNucleic Acids ProteinsProteins
Carbohydrates-Carbohydrates-starches and starches and sugarssugars
Lipids-fats, oils and Lipids-fats, oils and waxeswaxes
Nucleic Acids-DNA Nucleic Acids-DNA and RNAand RNA
Proteins- linked Proteins- linked amino acidsamino acids
CarbohydratesCarbohydrates
Compounds of C, H, Compounds of C, H, and Oand O
Living things use Living things use carbohydrates as carbohydrates as their main source of their main source of energyenergy
Plants and some Plants and some animals can use animals can use carbohydrates for carbohydrates for structurestructure
Living things store Living things store extra sugar as extra sugar as complex complex carbohydrates carbohydrates known as starchknown as starch
““carbon hydrate”carbon hydrate”
CCxx(H(H22O)O)xx
Formed when a carbon compound Formed when a carbon compound (CO(CO22) reacts with water) reacts with water
UsesUses EnergyEnergy StructureStructure Cell RecognitionCell Recognition ProtectionProtection
MonosaccharideMonosaccharide
MonomerMonomer Simplest sugarSimplest sugar
GlucoseGlucose GalactoseGalactose FructoseFructose RiboseRibose
Mono-Mono- Sacchar-Sacchar- They consist of one They consist of one
sugar and are sugar and are usually colorless, usually colorless, water soluble, water soluble, crystalline solidscrystalline solids
FructoseGlucose
DisaccharideDisaccharide
Covalent bond Covalent bond links two links two monosaccharides monosaccharides results in results in disaccharidedisaccharide Lactose-milkLactose-milk Sucrose-plantsSucrose-plants Maltose-grainsMaltose-grains
Di-Di- Sacchar-Sacchar-
Sucrose= glucose + fructose
Lactose= glucose + galactose
Maltose = glucose + glucose
LactoseLactose
SucroseSucrose
SucroseSucrose
SucroseSucrose
SucroseSucrose
StarchesStarches GlycogenGlycogen CelluloseCellulose ChitinChitin
StarchStarch
StarchStarch
Potato Corn
Oats
CelluloseCellulose
CelluloseCellulose
ChitinChitin
CarbohydratesCarbohydrates
LipidsLipids
Fats, oils, and waxesFats, oils, and waxes Generally not soluble in waterGenerally not soluble in water Many are made of a glycerol molecule Many are made of a glycerol molecule
with compounds of fatty acids with compounds of fatty acids attached.attached.
Saturated-has all possible H atoms Saturated-has all possible H atoms attachedattached
Un-saturated- has at least one double Un-saturated- has at least one double bond occupying an atom’s positionbond occupying an atom’s position
Glycerol Backbone
Saturated
Unsaturated
Saturated FatsSaturated Fats
Saturated FatsSaturated Fats
Unsaturated FatsUnsaturated Fats
Tend to be liquid at room temperatureTend to be liquid at room temperature Come from vegetable sourcesCome from vegetable sources Has at least one carbon-carbon bondHas at least one carbon-carbon bond Polyunsaturated-has more than one Polyunsaturated-has more than one
double bonddouble bond Corn oil, sesame oil, canola oil, and Corn oil, sesame oil, canola oil, and
peanut oil are polyunsaturatedpeanut oil are polyunsaturated
Unsaturated FatsUnsaturated Fats
Corn Oil
Canola Oil
Peanut Oil
NucleotidesNucleotides
Nucleic acids are assembled from Nucleic acids are assembled from individual monomers known as individual monomers known as nucleotidesnucleotides
Nucleotides have a 5-carbon sugar, a Nucleotides have a 5-carbon sugar, a phosphate group, and a nitrogenous phosphate group, and a nitrogenous base.base.
NucleotideNucleotide
Nucleic AcidsNucleic Acids
Store and transmit hereditary or Store and transmit hereditary or genetic information.genetic information.
Ribonucleic acid (RNA)- contains the Ribonucleic acid (RNA)- contains the sugar ribosesugar ribose
Deoxyribonucleic acid (DNA)- Deoxyribonucleic acid (DNA)- contains the sugar deoxyribosecontains the sugar deoxyribose
Arranged in sequence to form Arranged in sequence to form informational code that informational code that
DeoxyriboDeoxyribonuclnucleiceic AcidAcid
Deoxyribose-monosaccharide
RiboRibonucleicnucleic AcidAcid
Ribose- monosaccharide
RiboRibonucleicnucleic AcidAcid
ProteinsProteins
Macromolecules that contain nitrogen Macromolecules that contain nitrogen as well as carbon, hydrogen, and as well as carbon, hydrogen, and oxygenoxygen
Polymers, they are made of monomers Polymers, they are made of monomers called amino acids.called amino acids.
There are more than 20 amino acids There are more than 20 amino acids found in nature.found in nature.
Some amino acids are acidic or basic.Some amino acids are acidic or basic. Some are polar. Some are non-polar.Some are polar. Some are non-polar.
ProteinsProteins
The instructions for arranging amino The instructions for arranging amino acids into many different proteins are acids into many different proteins are stored in DNA.stored in DNA.
Some proteins control the rate of Some proteins control the rate of reactions, some form muscles, and reactions, some form muscles, and some transport substances or fight some transport substances or fight disease.disease.
ProteinsProteins
Protein TransportProtein Transport
EnzymesEnzymes
EnzymesEnzymes
Speed up chemical reactions that Speed up chemical reactions that take place in cellstake place in cells
Functioning depends on shape of Functioning depends on shape of twisted proteintwisted protein
Temperature and pH change shape Temperature and pH change shape of proteins and so change of proteins and so change functioning of enzymesfunctioning of enzymes
Chemical ReactionsChemical Reactions
Process that Process that changes one set of changes one set of chemicals into chemicals into another set of another set of chemicalschemicals
Reactants- go into Reactants- go into the reactionthe reaction
Products- come out Products- come out of the reactionof the reaction
Chemical reactions Chemical reactions always involve the always involve the breaking of bonds breaking of bonds in reactants and in reactants and the formation of the formation of new bonds in new bonds in productsproducts
CH3COOH + NaHCO3 CH3COONa + H2CO3
H2CO3 H2O + CO2
Baking Soda + Vinegar
Salt and Carbonic Acid
Carbonic Acid
Water and Carbon Dioxide
Energy in ReactionsEnergy in Reactions
Reactions that release energy often Reactions that release energy often occur spontaneouslyoccur spontaneously
Reactions that absorb energy will not Reactions that absorb energy will not occur without a source of energy.occur without a source of energy.
2H2 + O2 2H2O Burning releases energy
But . . .what do you have to have to start the fire?
Releasing EnergyReleasing Energy
Activation EnergyActivation Energy
The energy that is needed to get a The energy that is needed to get a reaction startedreaction started
Activation EnergyActivation Energy
Energy-AbsorbingEnergy-Absorbing
Endo-Endo- Therm-Therm-
Endo/ExoEndo/Exo
The reaction that The reaction that changes water into changes water into hydrogen and hydrogen and oxygen gas oxygen gas absorbs so much absorbs so much energy that it energy that it generally can’t generally can’t occur by itself.occur by itself.
Water can be made Water can be made through the through the burning reaction of burning reaction of Hydrogen and Hydrogen and Oxygen which Oxygen which produces lots of produces lots of energy and water.energy and water.
Energy ReleasingEnergy Releasing
Exo-
Therm-
CatalystCatalyst
Some chemical Some chemical reactions that reactions that make life possible make life possible are too slow or are too slow or have activation have activation energies that are energies that are too high to make too high to make them practical for them practical for living tissue.living tissue.
Amylase on cracker
CatalystCatalyst
EnzymesEnzymes
Proteins that act as Proteins that act as biological catalystsbiological catalysts
Speed up chemical Speed up chemical reactions that take reactions that take place in cellsplace in cells
Carbonic Carbonic anhydrase speeds anhydrase speeds up CO2 removal by up CO2 removal by a factor of 10 a factor of 10 millionmillion