The Chemistry of Carbon BUILDING BLOCKS OF LIFE

Why study Carbon? All life (on our planet) is carbon-based Cells ◦~72% H 2 O ◦~25% carbon compounds ◦Carbohydrates ◦Lipids ◦Proteins ◦Nucleic acids ◦~3% salts ◦Na, Cl, K ….

Organic Chemistry The study of carbon compounds C atoms are versatile building blocks ◦4 stable covalent bonds HH C H H

Hydrocarbons Combinations of C & H ◦Nonpolar ◦Not soluble in H 2 O ◦Hydrophobic ◦Stable ◦Very little attraction between molecules methane (simplest HC)

Hydrocarbons can grow …

Isomers Molecules with same molecular formula, but different structures ◦Different chemical properties ◦Different biological functions 6 carbons It’s the same, but different

Form affects function Structural differences create important functional significance ◦Amino acid alanine ◦L-alanine used in proteins ◦D-alanine is not ◦Medicine ◦L-alanine is active ◦D-alanine is not ◦Sometimes with tragic results stereoisomers

Form affects function Thalidomide ◦Prescribed to pregnant women in 50s & 60s ◦Reduced morning sickness, but … ◦Stereoisomer caused severe birth defects Control isomer in production? Evidence shows that body pH can cause racemizing

Functional groups generate diversity of molecules Substitute other atoms or groups around the carbon ◦Ethane vs ethanol ◦H replaced by an –OH ◦Nonpolar becomes polar ◦Gas becomes liquid ◦Different biological effects! ethane (C 2 H 6 ) ethanol (C 2 H 5 OH)

Functional groups Parts of organic molecules that are involved in chemical reactions ◦Give organic molecules distinctive properties ◦hydroxyl ◦carbonyl ◦carboxyl Affect reactivity ◦Makes hydrocarbons hydrophilic ◦Increases solubility in water ◦amino ◦sulfhydryl ◦phosphate

It makes a difference! Basic structure of male & female hormones is identical ◦Identical carbon skeleton ◦Attachment of different functional groups ◦Interact with different targets in the body ◦Different effects

Hydroxyl -OH ◦Organic compounds with OH = alcohols ◦Names typically end in –ol ◦ethanol

Carbonyl C=O ◦O double bonded to C ◦If C=O at end of molecule = aldehyde ◦If C=O in middle of molecule = ketone

Carboxyl -COOH ◦C double bonded to O & single bonded to OH group ◦Compounds with COOH = acids ◦Fatty acids ◦Amino acids

Amino -NH 2 ◦N attached to 2 H ◦Compounds with NH 2 = amines ◦Amino acids ◦NH 2 acts as a base ◦Ammonia picks up H+ from solution

Sulfhydryl -SH ◦S bonded to H ◦Compounds with SH = thiols ◦SH groups stabilize the structure of proteins

Phosphate -PO4 ◦P bonded to 4 O ◦Connects to C through an O ◦Lots of O = lots of negative charge ◦Highly reactive ◦Transfers energy between organic molecules ◦ATP, GTP, etc Becomes important with Gel electrophoresis

Macromolecules The Building Blocks of Life

Macromolecules Smaller organic molecules join together to form larger molecules 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 ◦Covalent bonds ◦Strong ◦Can store energy H2OH2O HO H HH Dehydration synthesis

How to build a polymer H2OH2O HO H HH Synthesis ◦Joins monomers by “taking” H 2 O out ◦One monomer donates –OH ◦One monomer donates H ◦Together these form H 2 O ◦Requires energy & enzymes ◦Called dehydration synthesis, condensation reaction, or anabolic reaction enzyme It requires energy to form bonds

How to break down a polymer Digestion ◦Use H 2 O to breakdown polymers ◦Reverse of dehydration synthesis ◦Remove one monomer at a time ◦H 2 O is split into H and OH ◦Requires enzymes ◦Releases energy ◦Called hydrolysis, digestion, or catabolic reaction H2OH2O HOH H H enzyme Breaking up is hard to do!

Any Questions?

Homework Compare the thermal properties of water with those of methane list, t-chart, venn diagram ….