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How To Make Biological Molecules (Ch. 5) Macromolecules • Smaller organic molecules join together to form larger molecules – macromolecules • 4 major classes of macromolecules: – carbohydrates – lipids – proteins – nucleic acids Polymers • Long molecules built by linking repeating building blocks in a chain – monomers • building blocks • repeated small units H 2O – covalent bonds HO H HO H Dehydration synthesis HO H How to build a polymer You gotta be open to “bonding! • Synthesis – joins monomers by “taking” H2O out • one monomer donates OH– • other monomer donates H+ • together these form H2O H 2O – requires energy & enzymes HO H Dehydration synthesis HO H enzyme Condensation reaction HO H How to break down a polymer Breaking up is hard to do! • Digestion – use H2O to breakdown polymers • reverse of dehydration synthesis • cleave off one monomer at a time • H2O is split into H+ and OH– – H+ & OH– attach to ends – requires enzymes – releases energy HO H2O enzyme H Hydrolysis Digestion HO H HO H Any Questions?? 2007-2008 CH2OH H O H OH H H OH HO H OH Carbohydrates energy molecules Carbohydrates • Carbohydrates are composed of C, H, O carbo - hydr - ate CH2O • Function: (CH2O)x – energy C6H12O6 – energy storage – raw materials – structural materials • Monomer: sugars • ex: sugars, starches, cellulose sugar sugar sugar sugar sugar sugar sugar sugar Sugars • Most names for sugars end in -ose • Classified by number of carbons – 6C = hexose (glucose) – 5C = pentose (ribose) – 3C = triose (glyceraldehyde) CH2OH H O H OH 6H HO H OH Glucose H CH2OH OH C O H HO H 5 OH O H HO H Ribose H H H C OH C 3OH H Glyceraldehyde Functional groups determine function carbonyl aldehyde carbonyl ketone Sugar structure 5C & 6C sugars form rings in solution Where do you find solutions in biology? In cells! Carbons are numbered Numbered carbons C 6' 5' C O 4' C C1' energy stored in C-C bonds C3' C2' Simple & complex sugars CH2OH H • Monosaccharides – simple 1 monomer sugars – glucose • Disaccharides – 2 monomers – sucrose • Polysaccharides – large polymers – starch O H OH H H OH HO Glucose H OH Building sugars • Dehydration synthesis monosaccharides | glucose H2O | glucose disaccharide | maltose glycosidic linkage Building sugars • Dehydration synthesis monosaccharides | glucose H2O | fructose Let’s go to the videotape! disaccharide | sucrose (table sugar) Polysaccharides • Polymers of sugars – costs little energy to build – easily reversible = release energy • Function: – energy storage • starch (plants) • glycogen (animals) – in liver & muscles – structure • cellulose (plants) • chitin (arthropods & fungi) Linear vs. branched polysaccharides slow release starch (plant) energy storage What does branching do? glycogen (animal) fast release Let’s go to the videotape! Polysaccharide diversity • Molecular structure determines function in starch in cellulose isomers of glucose structure determines function… 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 – most carnivores have not • 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?! Chitin, a different structural polysaccharide H OH CH2OH O OH H OH H H H NH C O CH3 (a) The structure of the chitin monomer. (b) Chitin forms the exoskeleton of arthropods. This cicada is molting, shedding its old exoskeleton and emerging in adult form. It is also found in Fungal Cell Walls. (c) Chitin is used to make a strong and flexible surgical thread that decomposes after the wound or incision heals. 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? – BACTERIA live in their digestive systems & help digest celluloserich (grass) meals Caprophage Ruminants Tell Ime about eat the rabbits, WHAT! again, George!
