unit 1 chapter 3: water & the fitness of life chapter 5: the structure & function of...
TRANSCRIPT
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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