The Chemistry of LifeThe Chemistry of Life

Characteristics of Living ThingsCharacteristics of Living Things

All living thingsAll living things Are made of one or more Are made of one or more cellscells Have a way to Have a way to reproducereproduce Grow and Grow and developdevelop Share a universal Share a universal genetic codegenetic code Must obtain material and use the Must obtain material and use the energyenergy from it from it Maintain a fairly stable Maintain a fairly stable internal environmentinternal environment Are able to Are able to respondrespond to to changeschanges in their in their

environment over timeenvironment over time

So why do we need to know about So why do we need to know about chemistry in a biology class?chemistry in a biology class?

All living things are made up of All living things are made up of chemicalschemicals. . The chemistry of living things is called The chemistry of living things is called biochemistrybiochemistry and includes concepts of and includes concepts of atomic structureatomic structure, , chemical bondingchemical bonding, and , and pHpH..

Chemistry BasicsChemistry Basics

Chemistry is the study of Chemistry is the study of mattermatter, its , its structurestructure and and compositioncomposition and and interactions.interactions.

All matter is made up of either All matter is made up of either elementselements or or compoundscompounds or a mixture of elements or a or a mixture of elements or a mixture of compounds or a mixture of mixture of compounds or a mixture of elements and compounds.elements and compounds.

Elements are the Elements are the chemicalchemical alphabet. alphabet.

More Basics…More Basics…

Element - Element - substance that can't be broken substance that can't be broken down into simpler substancesdown into simpler substances. .

9090 elements occur naturally, and about elements occur naturally, and about 2525 are essential to life.are essential to life.

4 elements make up 4 elements make up 96% 96% of human mass.of human mass. OOxygen, xygen, CCarbon, arbon, HHydrogen, ydrogen, NNitrogenitrogen Elements that occur in tiny amounts (such Elements that occur in tiny amounts (such

as iron and magnesium) are called as iron and magnesium) are called trace trace elements.elements.

Chemical BondingChemical Bonding

Two or more elements joined Two or more elements joined chemicallychemically make a compound. The way they are make a compound. The way they are joined is by a joined is by a chemical bondchemical bond..

There are 3 types of chemical bonds we There are 3 types of chemical bonds we are interested in for biology:are interested in for biology: CovalentCovalent IonicIonic HydrogenHydrogen

Atomic StructureAtomic Structure

Protons, neutrons, electrons, nucleus, Protons, neutrons, electrons, nucleus, energy levels, electron shellsenergy levels, electron shells

Ionic BondsIonic Bonds

Ionic bonds Ionic bonds are the result of two atoms are the result of two atoms that gain or lose electrons.that gain or lose electrons.

Ions have either a Ions have either a positivepositive or or negativenegative charge.charge.

Unlike charges attract each other so that Unlike charges attract each other so that electrical attraction holds electrical attraction holds the atoms the atoms together.together.

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Ionic BondingIonic Bonding

Covalent BondsCovalent Bonds

Form when Form when electronselectrons are are sharedshared between 2 between 2 atoms.atoms.

Atoms that Atoms that shareshare electrons form electrons form moleculesmolecules.. OrganicOrganic compoundscompounds which are which are moleculesmolecules that that

make up make up livingliving tissues are also formed with tissues are also formed with covalent bonds.covalent bonds.

Organic molecules have one or more Organic molecules have one or more carboncarbon atomsatoms, whose symbol is (C), combined with , whose symbol is (C), combined with hydrogen (H), combined with oxygen (O) and or hydrogen (H), combined with oxygen (O) and or nitrogen (N).nitrogen (N).

Covalent bondsCovalent bonds

WaterWater Water has many Water has many qualitiesqualities that make it important that make it important

to living things:to living things: It is It is transparenttransparent so sunlight passes through it to reach so sunlight passes through it to reach

plantsplants that live that live underwaterunderwater.. It can form positive or negative charged particles It can form positive or negative charged particles

called called ionsions.. It is an It is an universal solventuniversal solvent that can dissolve many that can dissolve many

substances easily so that they can be transported by substances easily so that they can be transported by the blood or other body fluids.the blood or other body fluids.

It is found It is found insideinside our cells and our cells and outsideoutside our cells our cells http://www.visionlearning.com/library/module_vie

wer.php?mid=57

It exists as a It exists as a liquidliquid at room temperature, and its at room temperature, and its solidsolid state state floatsfloats and does not sink. and does not sink.

Water is Water is polarpolar The The oxygenoxygen side of the side of the

molecule has a slightly molecule has a slightly negativenegative charge and the charge and the hydrogen hydrogen side of the molecule side of the molecule has a slightly has a slightly positivepositive charge charge which makes water a polar which makes water a polar molecule.molecule.

Hydrogen bonding-Hydrogen bonding- Attraction between the Attraction between the HH++

and the and the OO--

Water attracts other Water attracts other watewater r moleculesmolecules

Water molecules can Water molecules can form weak bonds called form weak bonds called hydrogenhydrogen bonds. bonds.

They make water They make water cohesivecohesive - a few - a few molecules stick together. molecules stick together.

This allows animals like a water This allows animals like a water strider to be able to “strider to be able to “walkwalk” on ” on

the the surfacesurface..

Hydrogen bonds cause Hydrogen bonds cause capillary actioncapillary action: : Water creeps up in thin tubesWater creeps up in thin tubes

Water molecules can Water molecules can form weak bonds form weak bonds called called hydrogenhydrogen bonds. They make bonds. They make water water cohesivecohesive - a - a few molecules stick few molecules stick together. together.

A. Water has a high A. Water has a high surface tensionsurface tension

Cohesion-Cohesion-Attraction Attraction between moleculesbetween molecules

Surface tension- Surface tension- surface of surface of HH22OO

molecules act like a molecules act like a filmfilm on surface on surface

Copy and answer questions:Copy and answer questions:

How many covalent bonds does water How many covalent bonds does water have?have?

Draw a water molecule and label the Draw a water molecule and label the charges.charges.

What is a hydrogen bond?What is a hydrogen bond? What gives water it unique properties?What gives water it unique properties? Why does water cling to surfaces?Why does water cling to surfaces? Why can a Jesus lizard walk on water?Why can a Jesus lizard walk on water?

3. Plants take 3. Plants take advantage of this to advantage of this to get waterget water

4. Water travels from 4. Water travels from roots to leavesroots to leaves

Water has a high heat of Water has a high heat of vaporizationvaporization

Takes Takes moremore energy to energy to breakbreak attraction and attraction and cause it to cause it to evaporateevaporate

This property helps This property helps coolcool human body human body

Water resists temperature Water resists temperature changechange

Requires Requires more heat more heat to to change change temperaturetemperature

Coastal areas have Coastal areas have less less fluctuationfluctuation in in temperature than other temperature than other areas of the same areas of the same latitudelatitude

Water makes up Water makes up 6060 to to 8080 % of all living % of all living organisms and organisms and 6565 to to 7070 % of the human % of the human body.body.

pHpH

Water is important because of its ability to form Water is important because of its ability to form ionsions. It forms positive . It forms positive HH ions and negative ions and negative OH OH ions.ions.

The pH scale is a measure of the amount of The pH scale is a measure of the amount of H H ionsions in a solution. in a solution.

The scale ranges from The scale ranges from 00 to to 1414 with with 77 being being neutralneutral..

Pure Pure waterwater has a has a pHpH of of 77.. A pH of A pH of 00 to to 6.9 6.9 is an acid, while a pH of is an acid, while a pH of 7.17.1 to to

1414 is a base or alkaline. is a base or alkaline.

Your body is designed so that each Your body is designed so that each systemsystem works best within a certain works best within a certain pH pH range.range.

AcidsAcids form positive H ions in solution. form positive H ions in solution.

pH of common substancespH of common substances Stomach acid 1.0 to 4.4 Stomach acid 1.0 to 4.4 Lemon juice 2.5Lemon juice 2.5 Soft drinks 2.0 – 3.5Soft drinks 2.0 – 3.5 Acid rain 4.5Acid rain 4.5 Pure water 7.0Pure water 7.0 Urine 7.2Urine 7.2 Saliva 7.4Saliva 7.4 Blood 7.4Blood 7.4 Ocean water 8.5Ocean water 8.5 Soap 10Soap 10 Oven cleaner 14Oven cleaner 14