Presentation on theme: "AP Biology Chapter 3: Structure and Function of Macromolecules (Independently brush up on Ch 2 and Ch 3.1)"— Presentation transcript:
1 AP Biology Chapter 3: Structure and Function of Macromolecules (Independently brush up on Ch 2 and Ch 3.1)
2 MacromoleculesSmaller organic molecules join together to form larger moleculesmacromolecules4 major classes of macromolecules:carbohydrateslipidsproteinsnucleic acids
3 PolymersLong molecules built by linking repeating building blocks in a chainmonomersbuilding blocksrepeated small unitscovalent bondsH2OHOH
4 How to build a polymer Synthesis joins monomers by “taking” H2O out one monomer donates OH–other monomer donates H+together these form H2Orequires energy & enzymesH2OHOHenzymeCondensation reaction - two molecules join, lose a smaller oneDehydration synthesis - Condensation reaction, in which the lost molecule = H2O
6 How to break down a polymer Digestionuse H2O to breakdown polymersreverse of dehydration synthesiscleave off one monomer at a timeH2O is split into H+ and OH–H+ & OH– attach to endsrequires hydrolytic enzymesreleases energyH2OHOHenzymeHydrolysisDigestion
7 DiscussionUnder what circumstances would you expect to find a cell conducting a great deal of dehydration synthesis?In which organs or under what circumstances would you expect to find body cells conducting hydrolysis?
8 Variety of PolymersEvery cell has thousands of varieties of macromoleculesThese molecules are constructed from only 40 to 50 common monomersAnalogy: 26 letters of the alphabet can be combined to form millions of wordsShortcoming: macromolecules are much longer than the average word and they can be branched or 3D.
17 Polysaccharides Polymers of sugars Functions: costs little energy to buildeasily reversible = release energyFunctions:energy storagestarch (plants)glycogen (animals)in liver & musclesstructurecellulose (plants)chitin (arthropods & fungi)
18 Polysaccharide diversity Molecular structure determines function - a major theme!in starchin celluloseIsomers of glucoseDifferent structure = connect to the next monomer in the chain differently = different 3D structure.Starch - helical. Cellulose - straight, with free OH to bond to neighboring celluloses = rigid structure!
19 Cellulose Most abundant organic compound on Earth herbivores have evolved a mechanism to digest cellulosemost carnivores have notthat’s why they eat meat to get their energy & nutrientscellulose = undigestible roughageCross-linking between polysaccharide chains:= rigid & hard to digestThe digestion of cellulose governs the life strategy of herbivores.Either you do it really well and you’re a cow or an elephant (spend a long time digesting a lot of food with a little help from some microbes & have to walk around slowly for a long time carrying a lot of food in your stomach)Or you do it inefficiently and have to supplement your diet with simple sugars, like fruit and nectar, and you’re a gorilla.
20 Helpful bacteria How can herbivores digest cellulose so well? BACTERIA live in their digestive systems & help digest cellulose-rich (grass) mealsRuminants
21 DiscussionIn EXACTLY 20 words, summarize the most important point or points to remember about carbohydrates.
23 Lipid Primary Function: long term energy storageconcentrated energy
24 Lipids Lipids are composed of C, H, O “Family groups” Same as carbohydrates, but different structure = different function!Lipids are composed of C, H, Olong hydrocarbon chains (H-C)“Family groups”fatsphospholipidssteroidsDo not form polymersbig molecules made of smaller subunitsnot a continuing chain
25 dehydration synthesis FatsStructure:glycerol (3C alcohol) + fatty acidfatty acid = long HC “tail” with carboxyl (COOH) group “head”enzymeH2Odehydration synthesis
26 Building Fats Triacylglycerol 3 fatty acids linked to glycerol ester linkage between OH & COOHhydroxylcarboxylBIG FAT molecule!!
27 Dehydration synthesis H2Odehydration synthesisenzymeH2OPulling the water out to free up the bondenzymeH2OenzymeH2O
28 DiscussionWhat kind of molecule would you expect to be hydrophobic - polar or non-polar?Why?Do you think lipids (such as fats, oils, waxes) are probably polar or non-polar?
29 Fats store energy Long HC chain Functions: polar or non-polar? hydrophilic or hydrophobic?Functions:energy storage2x carbohydratescushion organsmembranes &waterproofinginsulates bodythink whale blubber!
30 DiscussionShow me a human who doesn’t want to eat this and I’ll show you a LIAR.Knowing their major functions, hypothesize: what occurred in evolutionary history that led to humans enjoying the tastes of fatty and sugary foods?
31 Structure & Function Saturated Fats All C bonded to H No C=C double bondslong, straight chainmost animal fatssolid at room temp.contributes to cardiovascular disease (atherosclerosis) = plaque depositsMostly animal fats
32 Structure & Function Unsaturated Fats C=C double bonds in the fatty acidsplant & fish fatsvegetable oilsliquid at room temperaturethe kinks made by double bonded C prevent the molecules from packing tightly togetherMostly plant lipidsThink about “natural” peanut butter:Lots of unsaturated fats Oil separates outCompanies want to make their product easier to use:Stop the oil from separating Keep oil solid at room temp.Hydrogenate it = chemically alter to saturate itAffect nutrition?
33 DiscussionUnsaturated fats are widely considered to be healthier (sometimes called “good fats” for short) than saturated fats.Why might this be? (Hint: think of their structures, and what they might mean for how easily the body would use them for energy vs. storing them in fat cells)
35 Phospholipids Hydrophobic or hydrophilic? fatty acid tails = PO4 head =split “personality”interaction with H2O is complex & very important!
36 Phospholipids in water heads H2Otails H2Ocan self-assemble into “bubbles” called micellescan also form a phospholipid bilayerEarly Earth history - a cell part that self-assembles!bilayer
37 Why is this important? Phospholipids create a barrier in water define outside vs. insidethey make cell membranes!
38 Steroids Structure: 4 fused C rings + ?? different steroids created by attaching different functional groups to ringsdifferent structure creates different functionexamples: cholesterol, sex hormonescholesterol
39 Cholesterol Important cell component animal cell membranes precursor of all other steroidsincluding vertebrate sex hormoneshigh levels in blood may contribute to cardiovascular disease
40 Cholesterol Important component of cell membrane helps keep cell membranes fluid & flexible
41 From Cholesterol Sex Hormones What a big difference a few atoms can make!Same C skeleton, different functional groups
42 DiscussionIn EXACTLY 20 words, summarize the most important point or points to remember about lipids.