Chapter 2Chapter 2

The Chemistry of LifeThe Chemistry of Life

Chapter OutlineChapter Outline

Section 1: The Nature of Section 1: The Nature of MatterMatter

Section 2: Water and Section 2: Water and SolutionsSolutions

Section 3: Chemistry of CellsSection 3: Chemistry of Cells

Section 4: Energy and Section 4: Energy and Chemical Chemical ReactionsReactions

Section 2.1Section 2.1Nature of MatterNature of Matter

Why look at chemistry in a biology class?Why look at chemistry in a biology class?– All living organisms have chemical All living organisms have chemical

“machinery”“machinery”

2.1 Covers:2.1 Covers:– Atoms, Elements, Chemical BondingAtoms, Elements, Chemical Bonding

AtomsAtoms

Atom is the smallest unit of matter Atom is the smallest unit of matter that that cannot be broken down by cannot be broken down by chemical meanschemical means

Very small and always changingVery small and always changing

3 particles make up an atom3 particles make up an atom– Electrons (-) Electrons (-) – Protons (+)Protons (+)– Neutrons (neutral)Neutrons (neutral)

Attract each other…

*Therefore atom itself has no charge (negative electron cancels out positive proton)

Atomic StructureAtomic Structure

Electron CloudElectron Cloud made of made of electrons (-)electrons (-)

NucleusNucleus made made up of protons (+) up of protons (+) and neutrons and neutrons (neutral), (neutral), nucleus nucleus has a (+) chargehas a (+) charge

ElementElement

An element is a pure substance An element is a pure substance made of only one kind of atommade of only one kind of atom– Represented by chemical symbols (C, N, H)Represented by chemical symbols (C, N, H)– Elements have different atomic numbers Elements have different atomic numbers

(C=6, O=8)(C=6, O=8) Atomic number = # of protonsAtomic number = # of protons

Differences in Differences in ElementsElements

Atomic NumberAtomic Number all atoms of a all atoms of a particular element have the particular element have the same same number of protonsnumber of protons which is called which is called the atomic number.the atomic number.– Ex: Helium = 2 b/c it has 2 protonsEx: Helium = 2 b/c it has 2 protons

IsotopesIsotopes

Different number of neutrons than protonsDifferent number of neutrons than protons– Carbon 12, 13, 14Carbon 12, 13, 14

6 Protons6 Protons in each in each butbut Carbon 13 has 7 neutronsCarbon 13 has 7 neutrons and and carbon 14 has 8 neutronscarbon 14 has 8 neutrons

Energy LevelsEnergy Levels

Chemical BondingChemical Bonding

Atoms can join together to form a stable substanceAtoms can join together to form a stable substance– The force that joins atoms together is called a The force that joins atoms together is called a chemical chemical

bondbond

A compound is a substance made of 2 or more elements.A compound is a substance made of 2 or more elements.

3 Types of Bonds3 Types of Bonds– CovalentCovalent– HydrogenHydrogen– IonicIonic

Arrangement of electrons determine how atoms bond Arrangement of electrons determine how atoms bond togethertogether

Electron levelsElectron levelsClosest to nucleus = 2 electronsClosest to nucleus = 2 electronsSecond level = 8 electronsSecond level = 8 electrons

Atom becomes Atom becomes stablestable when the when the outer electron outer electron level is fulllevel is full

Covalent bondsCovalent bonds

Hydrogen =HHydrogen =H has has only 1 electron in only 1 electron in its outer most its outer most levellevelOxygen =OOxygen =O has has only 6 electrons only 6 electrons in its outer most in its outer most levellevelThey react to fill They react to fill each ones outer each ones outer most levelmost level

22

1

65

4

32

Form when 2+ atoms share electrons to form a molecule.

Ionic BondingIonic Bonding

Atoms gain or lose an electron, causing Atoms gain or lose an electron, causing them to be charged.them to be charged.

They become charged because they They become charged because they contain an contain an unequalunequal number of electrons number of electrons and protonsand protons

Gaining/Loosing an ElectronGaining/Loosing an Electron

Gaining an electron makes the atom Gaining an electron makes the atom negativenegative– You have more electrons (-) than protons (+)You have more electrons (-) than protons (+)

Loosing an electron makes the atom Loosing an electron makes the atom positivepositive– You have more protons (+) than electrons (-)You have more protons (+) than electrons (-)

Ionic Bond ExampleIonic Bond Example Na LOST an e- so it became more positive

Cl GAINED an e- so it became more negative

Hydrogen bondsHydrogen bonds

Electrons more strongly Electrons more strongly attracted to the oxygen attracted to the oxygen nucleus than by the nucleus than by the hydrogen’shydrogen’s

This unequal distribution of This unequal distribution of electrical charge are called electrical charge are called polar moleculespolar molecules

Partially positive end of Partially positive end of one molecule is attracted one molecule is attracted to the partially negative to the partially negative end of anotherend of another

Polar MoleculePolar Molecule(Water)(Water)

Which pole attracts which pole?

Exit TicketExit Ticket

Draw a carbon atom (Atomic number = 6)Draw a carbon atom (Atomic number = 6)– Label all the parts and correctly show the Label all the parts and correctly show the

number of electrons in the right levelsnumber of electrons in the right levels

Write 3 things you learned todayWrite 3 things you learned today

Begin 2.1 Section ReviewBegin 2.1 Section Review– Page 30Page 30– Questions 1-4Questions 1-4– Finish for HWFinish for HW

Chapter 2Chapter 2Section 2Section 2

Water and SolutionsWater and Solutions

Water in Living ThingsWater in Living Things

• 70%70% of your body is made of water of your body is made of water• Water helps move nutrients and other Water helps move nutrients and other

substances into and out of your cellssubstances into and out of your cells

• Certain properties of water make it Certain properties of water make it such an important substance for lifesuch an important substance for life– Storage of heatStorage of heat– Cohesion & AdhesionCohesion & Adhesion

Storage of HeatStorage of Heat

• WaterWater heats more slowly and heats more slowly and retains heatretains heat longer than many longer than many other substancesother substances

• Many organisms release heat Many organisms release heat through water through water evaporationevaporation– SweatingSweating

• Helps maintain Helps maintain homeostasishomeostasis

Cohesion & AdhesionCohesion & Adhesion

• The The hydrogen bondshydrogen bonds betweenbetween water molecules water molecules cause the cause the cohesion of liquid watercohesion of liquid water

• CohesionCohesion– Attraction between substances of the same kindAttraction between substances of the same kind– Surface tensionSurface tension prevents water from breaking easily prevents water from breaking easily

• AdhesionAdhesion– Attraction between substances of a different kindAttraction between substances of a different kind

• Substances get wetSubstances get wet• Capillary actionCapillary action water molecules move up through a water molecules move up through a

narrow tube (stem of plant)narrow tube (stem of plant)

• Because of these water can move up the stems of Because of these water can move up the stems of leavesleaves

Aqueous SolutionsAqueous Solutions

• Many substances dissolve in waterMany substances dissolve in water• Solution is: Solution is: a mixture in which one or more a mixture in which one or more

substances are evenly distributed in another substances are evenly distributed in another substance.substance.

• Because certain substances can dissolve Because certain substances can dissolve in water they can more easily move in water they can more easily move throughout the bodythroughout the body

PolarityPolarity

• Enables many substances to dissolve in Enables many substances to dissolve in waterwater– When ionic compounds are dissolved in water, When ionic compounds are dissolved in water,

the ions become surrounded by polar water the ions become surrounded by polar water moleculesmolecules•Ions and molecules become evenly distributed in Ions and molecules become evenly distributed in

the waterthe water

• Non polar molecules do not dissolve in Non polar molecules do not dissolve in water well (oils)water well (oils)

Acids and BasesAcids and Bases

• PuPure waterre water always has a always has a even even concentrationconcentration of hydrogen ions (H+) of hydrogen ions (H+) and hydroxide ions (OH-)and hydroxide ions (OH-)

• Acids have a higher concentration of Acids have a higher concentration of hydrogen ions.hydrogen ions.

• Bases have a higher concentration of Bases have a higher concentration of hydroxide ions.hydroxide ions.

pH ScalepH Scale

2.3 Chemistry of Cells2.3 Chemistry of Cells

• Most matter in your body that isn’t water ISIS an organic molecule

– Organic = Carbon based• 4 classes of organic molecules in your

body (can’t function w/o them)

– Carbohydrates– Lipids– Proteins– Nucleic Acids

Carbohydrates

• Organic molecules made of carbon, hydrogen and oxygen

• Major source of Major source of energyenergy for the body for the body

• Found in most foods (fruits, veggies, grain) in the form of sugars– 3 types of sugars

• Monosaccharide (1 sugar unit)

• Disaccharide (2 sugar units)• Polysaccharide ( 3+ sugar units)

– Macromolecule large molecule made of many smaller

Examples of Sugars (Carbs)• PolysaccharidesPolysaccharides

storehouses for energy

• starch, glycogen, cellulose– Starch – made by

plants– Glycogen- made by

animals• Both made from linked

glucose molecules (pg 34)

– Cellulose- made by plants (for structure)

LipidsLipids• Non-polar molecules… soluble or non-

soluble?

• Fats, phospholipids, steroids and waxes• Steroids (cholesterol, estrogen, testosterone)

• Important for structure and function of cell membranes

• Lipids store energy

StructureStructure• 3 fatty acids bonded to a glycerol molecule

backbone (pg 35)

• Fatty acid is long chain of carbon atoms carbon atoms with hydrogen bondedwith hydrogen bonded to them

• Strong bonds between carbon and hydrogen can store lots of energy

Saturated and Saturated and UnsaturatedUnsaturated

Saturated• All carbons are

bonded to 2+ hydrogen

• Most animal fats– Butter, lard, grease

• Usually solids at room temperature

Unsaturated• Some carbons linked

by a double covalent bond– Causes kinks in chain

• Plant oils, olive oil, fish oils

• Liquids at room temperature

Unsaturated Fats

Proteins• Large molecules formed by linked smaller

molecules called amino acids (AA)– AA are building blocks of proteins

• Only 20 AA

• Cause various shapes of proteins• Some proteins are enzymes (help chemical

reactions)• Others used for structure

– Skin, ligaments, bone (Collagen)– Hair & nails (keratin)– Muscle (myoglobin)– Blood (hemoglobin)

Example of a Protein??? Enzymes!

• ENZYMES!– Lower the amount of energy needed to start

the reaction without changing the original reactants.

– Reaction runs faster!

Energy Chemical Reaction

Reactant 1 Products +Reactant 2

Hydrogen

Oxygenwater

Enzymes• Shape specific - Fits like puzzle piece

– Active site

• Each enzyme has its own specific substrate (reactant)

Enzymes• What affects enzymes?

– pH, temperature, environment

Collagen

Hemoglobin

Nucleic AcidsNucleic Acids• All cells contain nucleic acids (in all cells)• Long chain of smaller molecules (nucleotides)

– 3 parts • Sugar• Base• Phosphate group (P& O)

• 2 types of nuclei acids– DNA- deoxyribonucleic acid– RNA- ribonucleic acid

DNADNA• 2 strands of

nucleotides that spiral around each other

• Chromosomes contain long strands of DNA (stores heredity)

RNA• Single strand of nucleotides

• Key roles in protein synthesis

• Acts as enzyme helping chemical

reactions link AA to form proteins