AP Biology CH. 5 Macromolecules Building Blocks of Life

AP Biology Macromolecules  Smaller organic molecules join together to form larger molecules  macromolecules  4 major classes of macromolecules:  carbohydrates  lipids  proteins  nucleic acids

AP Biology H2OH2O HO H HH Polymers  Long molecules built by linking repeating building blocks in a chain  monomers  building blocks  repeated small units  covalent bonds Dehydration synthesis

AP Biology H2OH2O HO H HH How to build a polymer  Synthesis  joins monomers by “taking” H 2 O out  one monomer donates OH –  other monomer donates H +  together these form H 2 O  requires energy & enzymes enzyme Dehydration synthesis Condensation reaction You gotta be open to “bonding!

AP Biology H2OH2O HOH H H How to break down a polymer  Digestion  use H 2 O to breakdown polymers  reverse of dehydration synthesis  cleave off one monomer at a time  H 2 O is split into H + and OH –  H + & OH – attach to ends  requires enzymes  releases energy Breaking up is hard to do! Hydrolysis Digestion enzyme

AP Biology Carbohydrates  Carbohydrates are composed of C, H, O carbo - hydr - ate CH 2 O (CH 2 O) x C 6 H 12 O 6  Function:  energy u energy storage  raw materials u structural materials  Monomer: sugars  ex: sugars, starches, cellulose sugar C 6 H 12 O 6 (CH 2 O) x

AP Biology Sugars  Most names for sugars end in -ose  Classified by number of carbons  6C = hexose (glucose)  5C = pentose (ribose)  3C = triose (glyceraldehyde) OH H H HO CH 2 OH H H H OH O Glucose H OH HO O H H H Ribose CH 2 OH Glyceraldehyde H H H H OH O C C C 653

AP Biology Functional groups determine function carbonyl ketone aldehyde carbonyl

AP Biology Sugar structure 5C & 6C sugars form rings in solution Carbons are numbered Where do you find solutions in biology? In cells!

AP Biology Numbered carbons C CC C C C 1' 2'3' 4' 5' 6' O energy stored in C-C bonds

AP Biology Simple & complex sugars  Monosaccharides  simple 1 monomer sugars  glucose  Disaccharides  2 monomers  sucrose  Polysaccharides  large polymers  starch OH H H HO CH 2 OH H H H OH O Glucose

AP Biology Building sugars  Dehydration synthesis | fructose | glucose monosaccharides | sucrose (table sugar) disaccharide H2OH2O

AP Biology 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)

AP Biology Linear vs. branched polysaccharides starch (plant) glycogen (animal) energy storage What does branching do? Let’s go to the videotape! slow release fast release

AP Biology Polysaccharide diversity  Molecular structure determines function  isomers of glucose  structure determines function… in starchin cellulose

AP Biology Digesting starch vs. cellulose starch easy to digest enzyme cellulose hard to digest

AP Biology 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?!

Regents Biology 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

Regents Biology Helpful bacteria  How can herbivores digest cellulose so well?  BACTERIA live in their digestive systems & help digest cellulose-rich (grass) meals Ruminants Tell me about the rabbits, again, George! I eat WHAT!

AP Biology Lipids long term energy storage concentrated energy

AP Biology Lipids  Lipids are composed of C, H, O  long hydrocarbon chains (H-C)  “Family groups”  fats  phospholipids  steroids  Do not form polymers  big molecules made of smaller subunits  not a continuing chain

AP Biology Fats  Structure:  glycerol (3C alcohol) + fatty acid  fatty acid = long HC “tail” with carboxyl (COOH) group “head” dehydration synthesis H2OH2O enzyme

AP Biology Building Fats  Triacylglycerol  3 fatty acids linked to glycerol  ester linkage = between OH & COOH hydroxylcarboxyl

AP Biology Dehydration synthesis dehydration synthesis H2OH2OH2OH2OH2OH2OH2OH2O enzyme

AP Biology Fats store energy  Long HC chain  polar or non-polar?  hydrophilic or hydrophobic?  Function:  energy storage  concentrated  all H-C!  2x carbohydrates  cushion organs  insulates body  think whale blubber! Why do humans like fatty foods?

AP Biology Saturated fats  All C bonded to H  No C=C double bonds  long, straight chain  most animal fats  solid at room temp.  contributes to cardiovascular disease (atherosclerosis) = plaque deposits

AP Biology Unsaturated fats  C=C double bonds in the fatty acids  plant & fish fats  vegetable oils  liquid at room temperature  the kinks made by double bonded C prevent the molecules from packing tightly together mono-unsaturated? poly-unsaturated?

AP Biology Phospholipids  Structure:  glycerol + 2 fatty acids + PO 4  PO 4 = negatively charged

AP Biology Phospholipids  Hydrophobic or hydrophilic?  fatty acid tails =  PO 4 head =  split “personality” interaction with H 2 O is complex & very important! “repelled by water” “attracted to water” Come here, No, go away! hydrophobic hydrophillic

AP Biology Phospholipids in water  Hydrophilic heads “attracted” to H 2 O  Hydrophobic tails “hide” from H 2 O  can self-assemble into “bubbles”  bubble = “micelle”  can also form a phospholipid bilayer  early evolutionary stage of cell? bilayer water

AP Biology Why is this important?  Phospholipids create a barrier in water  define outside vs. inside  they make cell membranes! Tell them about soap!

AP Biology Steroids  Structure:  4 fused C rings + ??  different steroids created by attaching different functional groups to rings  different structure creates different function  examples: cholesterol, sex hormones cholesterol

AP Biology Cholesterol  Important cell component  animal cell membranes  precursor of all other steroids  including vertebrate sex hormones  high levels in blood may contribute to cardiovascular disease

AP Biology Cholesterol helps keep cell membranes fluid & flexible Important component of cell membrane

AP Biology From Cholesterol  Sex Hormones  What a big difference a few atoms can make!