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