UNIT 1

Chapter 3: Water & the Fitness of LifeChapter 5: The Structure & Function of

Macromolecules

The Nature of WaterThe Nature of Water

Water’s chemical properties make life Water’s chemical properties make life possible on Earth:possible on Earth:– water is a water is a polarpolar molecule molecule– organisms depend on the cohesion of water organisms depend on the cohesion of water

moleculesmolecules– water moderates temperatures on Earthwater moderates temperatures on Earth– solid water (ice) floatssolid water (ice) floats– water is an ALMOST universal solventwater is an ALMOST universal solvent

Water is a Polar MoleculeWater is a Polar Molecule

Oxygen is a VERY Oxygen is a VERY electronegativeelectronegative atom atom– region around oxygen is has a slight negative region around oxygen is has a slight negative

charge; region around hydrogens has a slight charge; region around hydrogens has a slight positive chargepositive charge

One water molecule One water molecule can can hydrogen bondhydrogen bond with up to 4 other with up to 4 other water moleculeswater molecules

Organisms Depends on the Cohesion of Organisms Depends on the Cohesion of Water MoleculesWater Molecules

Hydrogen bonds are constantly being Hydrogen bonds are constantly being broken and reformedbroken and reformed– the phenomenon of the phenomenon of cohesioncohesion describes how describes how

water molecules are held to one anotherwater molecules are held to one another

Water molecules also Water molecules also adhereadhere to other to other substances/surfacessubstances/surfaces

Surface tensionSurface tension makes makes water behave as if covered water behave as if covered by a filmby a film

Water Moderates Temperatures on Water Moderates Temperatures on EarthEarth

Definitions:Definitions:– kinetic energykinetic energy– heatheat– temperaturetemperature

Heat is measured in units called Heat is measured in units called caloriescalories (cal)(cal)– amount of heat necessary to raise one gram amount of heat necessary to raise one gram

of water by 1°Cof water by 1°C

The The specific heatspecific heat of a substance is the of a substance is the amount of heat that needs to be amount of heat that needs to be gained/lost to raise/lower it’s temperature gained/lost to raise/lower it’s temperature by 1°Cby 1°C– water = 1water = 1– ethyl alcohol = 0.6ethyl alcohol = 0.6– iron = 0.1iron = 0.1

Bodies of water act to moderate air Bodies of water act to moderate air temperaturestemperatures– ocean temperatures and coastal areas are ocean temperatures and coastal areas are

more stable than inlandmore stable than inland

Water requires a lot of heat to vaporizeWater requires a lot of heat to vaporize– 580 calories required to vaporize 1g of water580 calories required to vaporize 1g of water– hydrogen bonds must be broken firsthydrogen bonds must be broken first

Evaporative coolingEvaporative cooling prevents water from prevents water from vaporizing too much or too quicklyvaporizing too much or too quickly

Solid Water (ice) FloatsSolid Water (ice) Floats

Ice is less dense than liquid waterIce is less dense than liquid water– a volume of water expands ~109% as it a volume of water expands ~109% as it

freezesfreezes

Water is an ALMOST Universal SolventWater is an ALMOST Universal Solvent

The polarity of water makes it able to form The polarity of water makes it able to form hydrogen bonds with charged and other hydrogen bonds with charged and other polar moleculespolar molecules

Water can interact with molecules that are Water can interact with molecules that are ionic or polarionic or polar– hydrophilichydrophilic

Non-polar molecules are insoluble in water Non-polar molecules are insoluble in water and will not dissolveand will not dissolve– hydrophobichydrophobic (ex. oil) (ex. oil)

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Most Macromolecules are PolymersMost Macromolecules are Polymers

Three of the four macromolecules Three of the four macromolecules (Carbohydrates, proteins, and nucleic (Carbohydrates, proteins, and nucleic acids…not lipids) form chainlike structures acids…not lipids) form chainlike structures called called polymerspolymers Individual pieces, Individual pieces, monomersmonomers, are joined , are joined

to create polymersto create polymers Monomers joined by Monomers joined by dehydrationdehydration

(condensation) reaction(condensation) reaction Polymers disassembled by Polymers disassembled by hydrolysishydrolysis

Dehydration & HydrolysisDehydration & Hydrolysis

Dehydration: one monomer provides Dehydration: one monomer provides a hydrogen, the other provides a a hydrogen, the other provides a hydroxylhydroxyl

Hydrolysis: water is used to “restore” Hydrolysis: water is used to “restore” a hydrogen to one monomer and a a hydrogen to one monomer and a hydroxyl to the otherhydroxyl to the other Common to the digestive processCommon to the digestive process

CarbohydratesCarbohydrates

Carbohydrates exist as monomers, Carbohydrates exist as monomers, dimers, and polymersdimers, and polymers Special names: Special names: monosaccharidemonosaccharide, ,

disaccharidedisaccharide, , polysaccharidepolysaccharide

Monosaccharides are joined by Monosaccharides are joined by dehydration reactionsdehydration reactions Bond created: Bond created: glycosidic linkageglycosidic linkage

Polysaccharides are Polysaccharides are monosaccharides joined by many monosaccharides joined by many glycosidic linkagesglycosidic linkages

Polysaccharides perform storage and Polysaccharides perform storage and structural rolesstructural roles StarchStarch is composed entirely of glucose is composed entirely of glucose

monomersmonomers

Plants store starch in Plants store starch in plastidsplastids

CelluloseCellulose is stored in plants’ cell walls is stored in plants’ cell walls

Animals store glucose in the form of Animals store glucose in the form of glycogenglycogen

Highly branched like amylopectinHighly branched like amylopectin

Chitin Chitin is found in exoskeletons of is found in exoskeletons of arthropods and cell walls of many fungiarthropods and cell walls of many fungi

LipidsLipids

Lipids (fats) are not constructed of Lipids (fats) are not constructed of monomersmonomers Created from Created from glycerolglycerol and and fatty acidsfatty acids

Fatty acids are joined to glycerol by Fatty acids are joined to glycerol by an an ester linkageester linkage 3 fatty acids + 1 glycerol = 3 fatty acids + 1 glycerol = triglyceridetriglyceride

Fatty acids vary in the number of Fatty acids vary in the number of carbons and the number of double carbons and the number of double bonds present between carbonsbonds present between carbons No double bonds = No double bonds = saturatedsaturated One double bond = One double bond = unsaturatedunsaturated More than one double bond = More than one double bond =

polyunsaturatedpolyunsaturated

PhospholipidsPhospholipids contain two fatty acids contain two fatty acids and a phosphate groupand a phosphate group

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ProteinsProteins

Proteins are instrumental in virtually Proteins are instrumental in virtually everything an organism doeseverything an organism does

They are polymers constructed of They are polymers constructed of amino acidamino acid monomers monomers Combinations of 20 amino acids are Combinations of 20 amino acids are

joined to form joined to form polypeptidespolypeptides

Amino acids are categorized based Amino acids are categorized based on their propertieson their properties

Amino acids are joined by Amino acids are joined by dehydration reactions and form dehydration reactions and form peptide bondspeptide bonds

Polypeptide orientation: Polypeptide orientation: Amino end = N-terminusAmino end = N-terminus Carboxyl end = C-terminusCarboxyl end = C-terminus

Protein function is based on it’s 3-D Protein function is based on it’s 3-D shape, or shape, or conformationconformation Protein conformation has four levelsProtein conformation has four levels

PrimaryPrimary: linear sequence of amino acids: linear sequence of amino acids SecondarySecondary: : heliceshelicesandandpleatedpleatedsheets, sheets,

created by hydrogen bonding among created by hydrogen bonding among polypeptide backbonepolypeptide backbone

TertiaryTertiary: marked by hydrogen, ionic, and : marked by hydrogen, ionic, and covalent bonding between R-groups of covalent bonding between R-groups of amino acidsamino acids

QuaternaryQuaternary: occurs only when a protein is : occurs only when a protein is constructed of more than one polypeptideconstructed of more than one polypeptide

PrimaryPrimary SecondarySecondary TertiaryTertiary QuaternaryQuaternary

Nucleic AcidsNucleic Acids

Nucleic acids, Nucleic acids, DNADNA (DeoxyriboNucleic (DeoxyriboNucleic Acid) and Acid) and RNARNA (RiboNucleic Acid), (RiboNucleic Acid), store and transmit genetic store and transmit genetic informationinformation

DNA has the ability to replicate itself DNA has the ability to replicate itself as well as the ability to create RNAas well as the ability to create RNA RNA used to create proteinsRNA used to create proteins Central DogmaCentral Dogma: DNA : DNA RNA RNA proteins proteins

Nucleic acids are polymers of Nucleic acids are polymers of monomers called monomers called nucleotidesnucleotides Nucleotides = nitrogenous base + Nucleotides = nitrogenous base +

phosphate group + pentose (5 carbon) phosphate group + pentose (5 carbon) sugarsugar

Nucleotides are joined by Nucleotides are joined by phosphodiester linkphosphodiester link

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