AP Biology Life Substances The Role of Carbon

AP Biology Cells  Composed of 70-95% water the rest is made up of CARBON based compounds  Molecules that contain CARBON are said to be ORGANIC  Examples: methane, carbon dioxide, proteins

AP Biology Carbon’s Reactivity  Carbon (C) appears in the 2 nd row of the periodic table and has 4 bonding electrons in its valence shell.  Can form 4 bonds with other atoms (each bond consisting of one of the carbon’s electrons and one of the bonding atom’s electrons)  These bonds form a tetrahedron  A pyramid with a spike at the top and angles of 109°

AP Biology Hydrocarbons  Simplest organic compound  Gets its name because it only contains hydrogen and carbon atoms  Examples:  Methane  Ethane  Hexane  Isohexane  Cyclohexane

AP Biology Carbon Bonds Single bondingDouble bonding Triple bonding There appears to be no limit to the number of different structures carbon can form… Keep in mind  carbon can form 4 bonds. So, as the number of bonds between carbon atoms increases, the number of hydrogen atoms decreases

AP Biology Simple Hydrocarbons  Alkanes  carbon-carbon (single bond)  Chemical formula: C n H 2n+2  All enter combustion reactions with oxygen to produce CO2 and water vapor  They are flammable!  Alkenes  carbon = carbon (double bond)  Chemical formula: C n H 2n  Alkynes  carbon carbon=carbon (triple bond)  Chemical formula: C n H 2n-2

AP Biology Isomers  Structures that have identical chemical formulas but their structural formulas are different  Different chemical properties too  Because carbon can bond in so many ways, a single molecule can have different bonding configurations

AP Biology Structural Isomers  two substances having the same molecular formula but different physical and chemical properties because the arrangement of their component atoms is different. molecular formula physical chemical propertiesatoms

AP Biology Geometric Isomers  A chemical compound having the same molecular formula as another but a different geometric configuration, as when atoms or groups of atoms are attached in different spatial arrangements on either side of a bond or a ring.

AP Biology Enantiomers  Two substances having the same molecular formula but they are mirror images of one another.

AP Biology What type of isomer are these?

AP Biology Functional Groups  Hydroxyl – OH  These are referred to as alcohols  The existence of a functional group completely changes the chemical properties of a molecule  Example:  Ethane (2C alkane): gas at room temp  Ethanol (2C alcohol): liquid at room temp  Common drinking alcohol  active ingredient in “alcoholic” beverages such as beer and wine

AP Biology OH H H HO CH 2 OH H H H OH O Carbohydrates energy molecules

AP Biology Carbohydrates

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

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 Sugar structure 5C & 6C sugars form rings in solution Carbons are numbered Where do you find solutions? 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 Dehydration Synthesis= Polymerization Remove H 2 O 2 Monomers Bond= Polymer Anabolic reaction Anabolic reaction Produces polymer Produces polymer Monomer + Monomer  Polymer + Water Monomer + Monomer  Polymer + Water

AP Biology Building sugars  Dehydration synthesis glycosidic linkage | glucose | glucose monosaccharidesdisaccharide | maltose

AP Biology Building sugars  Synthesis | fructose | glucose monosaccharides | sucrose (table sugar) disaccharide Let’s go to the videotape!

AP Biology Catabolic reaction Catabolic reaction Produces monomers Produces monomers Ex) Polysaccharides  monosaccharides Ex) Polysaccharides  monosaccharides Polymer + Water  Monomer + Monomer Polymer + Water  Monomer + Monomer Hydrolysis Add H 2 O Separate polymer into: 2 monomers

AP Biology Polysaccharides  Polymers of sugars  costs little energy to build  easily reversible = release energy  Function:  energy storage  starch (plants)  glycogen (animals)  structure = building materials  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!

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 can digest cellulose  most carnivores cannot digest cellulose  that’s why they eat meat to get their energy & nutrients  cellulose = roughage BIG DEAL! Who can live on this stuff?!

AP 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

AP Biology Helpful bacteria  How can cows digest cellulose?  bacteria live in their gut & help digest cellulose-rich (grass) meals

AP Biology Let’s build some Carbohydrates!