Presentation on theme: "AP Biology Chapter 3: Structure and Function of Macromolecules (Independently brush up on Ch 2 and Ch 3.1)"— Presentation transcript:
AP Biology Chapter 3: Structure and Function of Macromolecules (Independently brush up on Ch 2 and Ch 3.1)
Macromolecules Smaller organic molecules join together to form larger molecules macromolecules 4 major classes of macromolecules: carbohydrates lipids proteins nucleic acids
H2OH2O HO H HH Polymers Long molecules built by linking repeating building blocks in a chain monomers building blocks repeated small units covalent bonds
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, in which the lost molecule = H2O Condensation reaction - two molecules join, lose a smaller one
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 hydrolytic enzymes releases energy Hydrolysis Digestion enzyme
Discussion Under 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 ?
Variety of Polymers Every cell has thousands of varieties of macromolecules These molecules are constructed from only 40 to 50 common monomers Analogy: 26 letters of the alphabet can be combined to form millions of words Shortcoming: macromolecules are much longer than the average word and they can be branched or 3D.
a.k.a. wheeee energy! :D
Carbohydrates Carbohydrates are composed of C, H, O carbo - hydr - ate CH 2 O) x C 6 H 12 O 6 Function: energy u energy storage raw materials u structural materials Monomer: sugars (monosaccharide) sugar C 6 H 12 O 6 (CH 2 O) x
Sugars Most names for sugars end in - ose Classified by number of carbons 6C = hexose (glucose) 5C = pentose (ribose) 3C = triose (glyceraldehyde) 653
Sugar structure 5C & 6C sugars form rings in solution
Numbered carbons C CC C C C 1' 2'3' 4' 5' 6' O energy stored in bonds Youll see this come back in our DNA unit…
Polysaccharides Polymers of sugars costs little energy to build easily reversible = release energy Functions: energy storage starch (plants) glycogen (animals) in liver & muscles structure cellulose (plants) chitin (arthropods & fungi)
Polysaccharide diversity Molecular structure determines function - a major theme! Isomers of glucose Different 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! in starch in cellulose
Cellulose Most abundant organic compound on Earth herbivores have evolved a mechanism to digest cellulose most carnivores have not thats why they eat meat to get their energy & nutrients cellulose = undigestible roughage
Helpful bacteria How can herbivores digest cellulose so well? BACTERIA live in their digestive systems & help digest cellulose-rich (grass) meals Ruminants
Discussion In EXACTLY 20 words, summarize the most important point or points to remember about carbohydrates.
Lipids: Fats & Oils
Lipid Primary Function: long term energy storage concentrated energy
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 Same as carbohydrates, but different structure = different function!
Fats Structure: glycerol (3C alcohol) + fatty acid fatty acid = long HC tail with carboxyl (COOH) group head dehydration synthesis H2OH2O enzyme
Building Fats Triacylglycerol 3 fatty acids linked to glycerol ester linkage between OH & COOH hydroxylcarboxyl
Discussion What 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? Why?
Fats store energy Long HC chain polar or non-polar? hydrophilic or hydrophobic? Functions: energy storage 2x carbohydrates cushion organs membranes & waterproofing insulates body think whale blubber!
Discussion Show me a human who doesnt want to eat this and Ill 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?
Structure & Function 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
Structure & Function 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
Discussion Unsaturated 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)
Phospholipids Structure: glycerol + 2 fatty acids + PO 4 PO 4 = negatively charged
Phospholipids Hydrophobic or hydrophilic? fatty acid tails = PO 4 head = split personality interaction with H 2 O is complex & very important!
Phospholipids in water heads H 2 O tails H 2 O can self-assemble into bubbles called micelles can also form a phospholipid bilayer Early Earth history - a cell part that self-assembles! bilayer
Why is this important? Phospholipids create a barrier in water define outside vs. inside they make cell membranes !
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
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
Cholesterol helps keep cell membranes fluid & flexible Important component of cell membrane
From Cholesterol Sex Hormones What a big difference a few atoms can make!
Discussion In EXACTLY 20 words, summarize the most important point or points to remember about lipids.