9/27/2015 1 Biology 102 Biology 102 Lecture 4: Lecture 4: Biomolecules Biomolecules • Molecules that make up living things Molecules that make up living things • Based on carbon Based on carbon-carbon bonds carbon bonds • Contain other elements (H, O, N, P, S) Contain other elements (H, O, N, P, S) • Simplest organic molecules are the hydrocarbons Simplest organic molecules are the hydrocarbons • Contain only C and H Contain only C and H • Non Non-polar polar • Soluble in water?? Soluble in water?? Biomolecules Biomolecules • Biomolecules Biomolecules are are modified hydrocarbons modified hydrocarbons • Contain functional Contain functional groups that change groups that change the chemical the chemical properties of the properties of the molecule molecule Biomolecules Biomolecules • 4 broad categories of 4 broad categories of biomolecules biomolecules Biomolecules Biomolecules • All All biomolecules biomolecules are built in the same are built in the same fundamental way, regardless of complexity fundamental way, regardless of complexity Biomolecules Biomolecules • Make up less than 3% of human body weight Make up less than 3% of human body weight • Much more prevalent in plants Much more prevalent in plants • Made of exclusively C, H, O Made of exclusively C, H, O • Ratio of 1:2:1 or CH Ratio of 1:2:1 or CH 2 O (= O (= carbo carbo-hydrate) hydrate) Carbohydrates Carbohydrates
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Biology 102Biology 102
Lecture 4: Lecture 4: BiomoleculesBiomolecules
•• Molecules that make up living thingsMolecules that make up living things
•• Based on carbonBased on carbon--carbon bondscarbon bonds
•• Contain other elements (H, O, N, P, S)Contain other elements (H, O, N, P, S)
•• Simplest organic molecules are the hydrocarbonsSimplest organic molecules are the hydrocarbons
•• Contain only C and HContain only C and H
•• NonNon--polarpolar
•• Soluble in water??Soluble in water??
BiomoleculesBiomolecules
•• BiomoleculesBiomolecules are are
modified hydrocarbonsmodified hydrocarbons
•• Contain functional Contain functional
groups that change groups that change
the chemical the chemical
properties of the properties of the
moleculemolecule
BiomoleculesBiomolecules
•• 4 broad categories of 4 broad categories of biomoleculesbiomolecules
BiomoleculesBiomolecules
•• All All biomoleculesbiomolecules are built in the same are built in the same fundamental way, regardless of complexityfundamental way, regardless of complexity
BiomoleculesBiomolecules
•• Make up less than 3% of human body weightMake up less than 3% of human body weight
•• Much more prevalent in plantsMuch more prevalent in plants
•• Made of exclusively C, H, OMade of exclusively C, H, O
•• Ratio of 1:2:1 or CHRatio of 1:2:1 or CH22O (= O (= carbocarbo--hydrate)hydrate)
•• Carboxyl group at one endCarboxyl group at one end
•• Polarity??Polarity??
•• Saturated or unsaturated Saturated or unsaturated –– with what?with what?
Fatty AcidsFatty Acids
•• Saturated or unsaturated with Saturated or unsaturated with hydrogenshydrogens
•• Carbon needs 4 bonds to be stableCarbon needs 4 bonds to be stable
•• Has 3 options to get themHas 3 options to get them
C C CC CC
Carbon SaturationCarbon Saturation
•• In a fatty acid, almost all carbons are bound to 2 In a fatty acid, almost all carbons are bound to 2 other carbonsother carbons
•• This builds the backbone of the fatty acid chainThis builds the backbone of the fatty acid chain
C C CC CC
Carbon SaturationCarbon Saturation
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•• If all bonds between carbons are single, a If all bonds between carbons are single, a greater number of greater number of hydrogenshydrogens can bindcan bind
•• This is said to be a This is said to be a saturatedsaturated fatty acid fatty acid –– one one with the maximum number of with the maximum number of hydrogenshydrogens
C C CC CC
Carbon SaturationCarbon Saturation
HH HH HH
HH HH HH
•• Every carbon has 4 single bondsEvery carbon has 4 single bonds
•• 2 with carbons2 with carbons
•• 2 with 2 with hydrogenshydrogens (except at the ends)(except at the ends)
Saturated Fatty AcidsSaturated Fatty Acids
•• Very stable Very stable –– not prone to ranciditynot prone to rancidity
•• Solid at room temperatureSolid at room temperature
•• Found in butter, animal fats, eggs, coconut oil, Found in butter, animal fats, eggs, coconut oil, palm oil palm oil –– and in your body!and in your body!
Saturated Fatty AcidsSaturated Fatty Acids
•• Carbons can also form double bondsCarbons can also form double bonds
•• Leaves less room for hydrogenLeaves less room for hydrogen
•• Said to be Said to be unsaturatedunsaturated
Unsaturated Fatty AcidsUnsaturated Fatty Acids
•• Double bonds prone to rancidityDouble bonds prone to rancidity
•• Bent chains do not stack as tightlyBent chains do not stack as tightly
•• Liquid at room temperatureLiquid at room temperature
•• Found in plant oilsFound in plant oils
Unsaturated Fatty AcidsUnsaturated Fatty Acids
•• One double bond = One double bond = monounsaturatedmonounsaturated
•• Olive, avocadoOlive, avocado
•• > 1 double bond = > 1 double bond = polyunsaturatedpolyunsaturated
•• In the early 1900s, Proctor & Gamble cornered In the early 1900s, Proctor & Gamble cornered the market on cottonseed oilthe market on cottonseed oil
•• Electricity meant people weren’t using candles Electricity meant people weren’t using candles much anymore much anymore –– what to do with the oil?what to do with the oil?
An Unfortunate DiscoveryAn Unfortunate Discovery
•• Oil hydrogenation turns double bonds into single Oil hydrogenation turns double bonds into single bondsbonds
An Unfortunate DiscoveryAn Unfortunate Discovery
•• Don’t want to completely saturate oilDon’t want to completely saturate oil
•• Turns waxy and grossTurns waxy and gross
•• Instead only partially hydrogenate, which Instead only partially hydrogenate, which changes some of the double bonds from changes some of the double bonds from ciscis to to transtrans
An Unintended ConsequenceAn Unintended Consequence
•• Changes shape to something not found in natureChanges shape to something not found in nature
An Unintended ConsequenceAn Unintended Consequence
•• Changes the shapeChanges the shape
•• Fat behaves more like it’s saturatedFat behaves more like it’s saturated
An Unintended ConsequenceAn Unintended Consequence ShorteningShortening
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•• CheapCheap
•• Lend “buttery” quality to processed foodsLend “buttery” quality to processed foods
•• Used in crackers, cookies, pie crusts, French Used in crackers, cookies, pie crusts, French fries, fried chicken, even coffee creamerfries, fried chicken, even coffee creamer
•• Less prone to rancidity than vegetable oil, lard, Less prone to rancidity than vegetable oil, lard, or butteror butter
•• Extend shelf life of productsExtend shelf life of products
Trans Trans Fatty AcidsFatty Acids
•• Shape doesn’t occur in natureShape doesn’t occur in nature
•• No enzymes that break it down No enzymes that break it down –– in us, or in in us, or in bacteria!bacteria!
•• Solid at room temperature Solid at room temperature –– and at body and at body temperature!temperature!
•• Body doesn’t know how to deal with itBody doesn’t know how to deal with it
•• You’re probably eating more than you thinkYou’re probably eating more than you think
Trans Trans Fatty AcidsFatty Acids
Trans Trans Fat Free?? Don’t Buy It!!Fat Free?? Don’t Buy It!!
•• Shape does occur in natureShape does occur in nature
•• Prone to oxidationProne to oxidation
•• But at least your body knows what to do with it!But at least your body knows what to do with it!
CisCis Fatty AcidsFatty Acids
Cis fat
So Which Fat Is Healthiest?So Which Fat Is Healthiest?
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•• Form when fatty acids bind to glycerolForm when fatty acids bind to glycerol
•• Most common Most common dietarilydietarily = triglycerides= triglycerides
•• 3 fatty acids3 fatty acids
GlyceridesGlycerides
+ 3H2O
•• Very efficient longVery efficient long--term energy storageterm energy storage
•• Large molecules = high potential energyLarge molecules = high potential energy
•• Gram for gram more than twice the energy of Gram for gram more than twice the energy of carbohydratescarbohydrates
•• Fat deposits under skin and throughout body cut Fat deposits under skin and throughout body cut heat loss by 2/3heat loss by 2/3
•• Protects and cushions organsProtects and cushions organs
•• Virtually nonVirtually non--polar polar –– allows for more efficient allows for more efficient storagestorage
Triglycerides in the BodyTriglycerides in the Body
Problem: We have too much of it!Problem: We have too much of it!
•• Modified triglyceridesModified triglycerides
•• One fatty acid replaced One fatty acid replaced
with a phosphorus and with a phosphorus and
nitrogennitrogen--containing containing
functional groupfunctional group
PhospholipidsPhospholipids
•• Phosphorus group is polar = hydrophilicPhosphorus group is polar = hydrophilic
•• Fatty acids are nonFatty acids are non--polar = hydrophobicpolar = hydrophobic
•• Allows nonAllows non--polar molecules to associate with polar molecules to associate with waterwater
•• Extremely important in cell membrane structureExtremely important in cell membrane structure
•• More about them laterMore about them later
PhospholipidsPhospholipids•• Synthesized by all living organismsSynthesized by all living organisms
•• Humans make in liverHumans make in liver
•• Dietary cholesterol Dietary cholesterol esterifiedesterified and poorly and poorly absorbedabsorbed
•• High cholesterol usually due to metabolic High cholesterol usually due to metabolic disregulationdisregulation rather than dietary sourcesrather than dietary sources