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Carbohydrates sugar sugar sugar sugar sugar sugar Carbohydrates Carbohydrates are composed of C, H, O Function: carbo - hydr - ate CH2O energy storage u structural materials u Monomer: monosaccharide ex: sugars, starches, cellulose Simple & complex sugars Monosaccharides simple 1 monomer sugars u Glucose, fructose, galactose CH2OH H O H OH H H OH HO u Disaccharides 2 monomers u Sucrose, Lactose, Maltose u Polysaccharides large polymers u Starch, Cellulose, Glycogen, Chitin u Glucose H OH Building sugars Dehydration synthesis monosaccharides | glucose H2O | fructose disaccharide | sucrose (table sugar) Polysaccharides Polymers of monosaccharides costs little energy to build u easily reversible = release energy u Function: u energy storage starch (plants) glycogen (animals) in liver & muscles u structure cellulose (plants) chitin (arthropods & fungi) Digesting starch vs. cellulose starch easy to digest enzyme cellulose hard to digest enzyme Cellulose Most abundant organic compound on Earth herbivores have evolved a mechanism to digest cellulose u most carnivores have not u that’s why they eat meat to get their energy & nutrients cellulose = undigestible roughage But it tastes like hay! Who can live on this stuff?! Cow can digest cellulose well; no need to eat other sugars Gorilla can’t digest cellulose well; must add another sugar source, like fruit to diet Helpful bacteria How can herbivores digest cellulose so well? u u BACTERIA live in their digestive systems & help digest cellulose-rich (grass) meals This is called SYMBIOSIS Caprophage Ruminants Lipids Lipids Lipids are composed of C, H, O u long hydrocarbon chains (H-C) “Family groups” fats u phospholipids u steroids u Do not form polymers big molecules made of smaller subunits u not a continuing chain u FATS long term energy storage concentrated energy Building Fats Triglycerol (fancy name for FAT) u Glycerol linked to 3 fatty acids Fats store energy Long HC chain u hydrophilic or hydrophobic? Function: u Why do humans like fatty foods? energy storage concentrated all H-C! 2x carbohydrates cushion organs u insulates body u think whale blubber! Saturated fats All C bonded to H No C=C double bonds long, straight chain u most animal fats u solid at room temp. u contributes to cardiovascular disease (atherosclerosis) = plaque deposits Unsaturated fats C=C double bonds in the fatty acids plant & fish fats u vegetable oils u liquid at room temperature u the kinks made by double bonded C prevent the molecules from packing tightly together mono-unsaturated? poly-unsaturated? Saturated vs. unsaturated saturated unsaturated Phospholipids Hydrophilic heads “attracted” to H2O Hydrophobic tails “hide” from H2O Why is this important? Phospholipids create a barrier in water define outside vs. inside u they make cell membranes! u Steroids Structure: u 4 fused rings different steroids created by attaching different molecules to rings different structure creates different function u examples: cholesterol, sex hormones cholesterol Cholesterol Important cell component helps keep cell membranes fluid & flexible animal cell membranes u high levels in blood may contribute to cardiovascular disease u Proteins Proteins Multipurpose molecules Proteins Most structurally & functionally diverse group Function: involved in almost everything in living things u u u u u u u enzymes (pectinase, amylase) structure (skin, hair, nails) carriers & transport (hemoglobin) cell communication (insulin & other hormones) defense (antibodies) movement (muscle) storage (nuts/seeds) Proteins Structure u monomer = amino acids 20 different amino acids u polymer = polypeptide large & complex molecules complex 3-D shape hemoglobin Rubisco growth hormones Monomer: Amino acid Structure H central carbon u amino group u carboxyl group (acid) u R group (side chain) u H O | || —C— C—OH —N— | H R variable group different for each amino acid confers unique chemical properties to each amino acid like 20 different letters of an alphabet can make many words (proteins) Oh, I get it! amino = NH2 acid = COOH Protein structure & function Function depends on structure u 3-D structure twisted, folded, coiled into unique shape pepsin hemoglobin collagen Sickle cell anemia I’m hydrophilic! Just 1 out of 146 amino acids! But I’m hydrophobic! Protein denaturation Unfolding a protein u In Biology, size doesn’t matter, SHAPE matters! conditions that disrupt bonds temperature pH salinity u alter structure alter 3-D shape u destroys function some proteins can return to their functional shape after denaturation, many cannot