AP Biology Discuss the following with your group and be prepared to discuss with the class 1. Why is the shape of a molecule important? 2. How is a covalent bond different from ionic? 3. How are hydrogen bonds different from covalent? We are beginning our first Unit today: Bio-Molecules Right now, the test is set for Tuesday, Sept 17th

Functional groups -parts of organic molecules that are involved in chemical reactions They give organic molecules distinctive properties hydroxyl amino carbonyl (ketones and aldehydes) sulfhydryl carboxyl phosphate

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 larger Bio-molecule  Dehydration Synthesis (also called Condensation Reaction)  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 This is an example of an Anabolic, endergonic reaction.

H2OH2O HOH H H How to break down a larger molecule  Hydrolysis (also called Digestion)  use H 2 O to breakdown polymers  reverse of dehydration synthesis  takes off one monomer at a time  H 2 O is split into H + and OH –  H + & OH – attach to ends  requires enzymes  releases energy enzyme This is an example of an Catabolic, exergonic reaction.

Bio-Molecules  Large organic molecules formed by smaller molecules bonding together  macromolecules  4 major classes of macromolecules:  carbohydrates  lipids  proteins  nucleic acids

AP Biology Proteins Multipurpose molecules

Proteins  Various functions:  enzymes (speed up metabolism)  structure physical stability and movement (keratin-hair/nails/skin, collagen- bones/cartilage/tendons, myosin-muscles)  transport (hemoglobin- in red blood cells, proteins in cell membranes)  cell communication/regulatory  signals (insulin & other hormones)  receptors  defense (antibodies/recognize foreign invaders)  storage (hold amino acids for later use) - Most structurally & functionally diverse group

Amino acids  central carbon  Two functional groups:  carboxyl group (acid)  amino group  R group (side chain)  variable group that is different for each amino acid  gives unique chemical properties to each amino acid  like 20 different letters of an alphabet  can make many words (proteins) —N— H H C—OH || O R | —C— | H Protein monomer (building block)

Peptide Bonds – Linking of Amino Acids

Effect of different R groups: Nonpolar amino acids  nonpolar & hydrophobic

Effect of different R groups: Polar amino acids  polar or charged & hydrophilic

Building proteins  Peptide bonds  covalent bond between NH 2 (amino) of one amino acid & COOH (carboxyl) of another  C–N bond peptide bond dehydration synthesis H2OH2O

Building proteins  Polypeptide chains have direction  N-terminus = NH 2 end  C-terminus = COOH end  repeated sequence (N-C-C) is the polypeptide backbone

Protein structure & function hemoglobin  Function depends on structure  3-D structure  twisted, folded, coiled into unique shape collagen pepsin

Primary (1°) structure  Order of amino acids in chain  amino acid sequence determined by genes (DNA)  slight change in amino acid sequence can affect protein’s structure & its function  even just one amino acid change can make all the difference!

(Example of structure determining function) Sickle Cell Anemia What type of mutation is this?

Secondary (2°) structure  “Local folding”  folding along short sections of polypeptide  interactions between adjacent amino acids  H bonds  weak bonds between R groups  forms sections of 3-D structure  helix  pleated sheet

Tertiary (3°) structure  “Whole molecule folding”  interactions between distant amino acids and R groups

Quaternary (4°) structure  More than one polypeptide chain bonded together collagen = skin & tendons hemoglobin

Protein denaturation  Unfolding a protein  conditions that disrupt H bonds and ionic bonds  temperature  pH  salinity  alter 2° & 3° structure  alter 3-D shape  destroys functionality  some proteins can return to their functional shape after being denatured, many cannot

 Enzymes a type of protein that acts as a catalyst, speeding up chemical reactions

H2OH2O Substrate (sucrose) Fructose Glucose

Some enzymes require other atoms or molecules in order to function: -Cofactors: inorganic ions, such as iron, copper, or zinc that bind to enzymes in order to help break down specific substances. -Coenzymes: organic molecules that are required by certain enzymes to carry out catabolic reactions.