1 Chapter 3 Biochemistry Topics:Water Carbon Compounds Molecules of Life CPI

2 Water Water is polar, but the molecule is neutral  Slightly + end (hydrogens)  Slightly – end (oxygen) Water is covalently bonded Water is “universal” solvent; dissolves many solutes (but not all)  Ionic compounds  Sugars  Some proteins

3 Ionic Compounds in Solution Water dissolves ionic compounds Ionic cmpds in solution dissociate into the respective ions which are hydrated by water molecules NaCl in aqueous solution important for proper body function; ie, muscle contraction & nerve impulses Dissociated ions in aqueous solution are necessary for many body functions; they are electrolytes

4 Hydrogen Bonding Bond type occurring between a hydrogen atom (  +) and a negatively charged area of another atom Weak bond, easily broken Bond type between DNA base pairs Responsible for many structural shapes of biological molecules; holds the folds/bends of molecules in place to ensure functionality

5 Capillary Action Cohesion - attractive force between molecules of the same type  Surface tension is an example; H 2 O forms rounded drops due to H bonding between H 2 O molecules Adhesion – attractive force between molecules of different types Capillary Action – occurs when these forces work together; H 2 O can move against gravity in this way

6 Specific Heat The quantity of heat req’d to raise a unit of mass of a homogeneous material 1K or 1ºC at constant temp/pressure Specific heat H 2 O = 1 Takes much E to heat of body of H 2 O; takes long time for heated H 2 O to cool

7 Organic Compounds Contain CARBON  Inorganic cmpds contain other elements Carbon bonds covalently to other nonmetals like C, N, O, H Carbon – 4 valence electrons  Can form up to 4 covalent bonds  Can form double & triple bonds  Can form straight chain, branched chain, or ringed molecules  (Look at handout)

8 Functional Groups A group of bonded atoms that influence the properties of the molecule of which it is a part One example: Alcohols  Functional group is –OH, hydroxyl group  It is attached to a carbon in a terminal (end) position  Makes the molecule polar  Can form H bonds Examples:  Methanol, Ethanol, Glycerol  (Look at handout)

9 Organic Molecules Can be simple to complex Units – monomers Monomer units bonded together form polymers Rxn type forming polymers – condensation reaction  Monomer units bonded forming H 2 O and polymer

10 Condensation Reaction To form sucrose (polymer) - condensation rxn is needed Glucose (monomer) + fructose (monomer) bond to form sucrose (polymer) + H 2 O (See handout for this rxn) Note that the reverse of a condensation rxn is Hydrolysis  Hydrolysis – rxn requiring H 2 O & breaking a polymer bond forming monomers

11 Energy Molecule ATP Energy made available to cells in form of a high E molecule called ATP  Adenosine Triphosphate  ATP is a polymer Energy stored in the terminal phosphate bonds Hydrolysis – add H 2 O, breaks polymer into units thus releasing energy (exergonic); yields ADP + P- OH Condensation Rxn – rebuilds ATP from ADP + P losing H 2 O (See next slide)

12 ATP Molecule

13 Carbohydrates Composed of C, H, O (CH 2 O) n n = 3 to 8 Saccharide – another term for sugar  Monosaccharide – 1 unit  Disaccharide – 2 units  Polysaccharide – many units 3 common monosaccharides  Glucose  Fructose  Galactose

14 Isomers Consider: Glucose, Mannose, Galactose Chemical formula: C 6 H 12 O 6 Structural formulas differ – how they are put together is different If chemical formula same, but structural formula different, then the compounds are isomers Remember: when structure differs, function differs

15 Isomers

16 Function of Carbohydrates Main functions: Energy source, form structural molecules Glycogen (Animals)  Polysaccharide of glucose  Branched chain  Stored in liver, muscles  Used for quick energy Starch (Plants)  Polysaccharide of glucose  Straight or branched chains  Energy source Cellulose (Plants)  Polysaccharide of glucose  Straight chain  Structural molecule; very strong  Not digestible by humans

17 Proteins Composed of C, H, O, N Polymers (macromolecules) made of monomer subunits called amino acids Amino acids bonded by peptide bonds; so proteins often called polypeptides Functions: compose tissues such as skin & muscle; compose enzymes (catalysts) Twenty amino acids; differ by the functional “R” group Twist & fold into many shapes

18 Amino Acid Structure Basic structure Functional Group -R Amino Group –NH 2 Carboxyl Group -COOH

19 Polypeptide (Protein) A condensation rxn forms a protein (polypeptide) Bond formed – peptide bond  (See next slide) Enzymes – special protein that lower activation energy (catalysts); thought to work by changing substrate shape, thus weakening bonds and so lowers E A Functions within tight parameters of temperature, pH, electrolyte balance, etc. When these exceeded, proteins may fail to function (denatured)

20 Formation of Peptide Bond

21 Lipids Large, non-polar molecules Store E efficiently Many C-H bonds Not miscible in H 2 O Monomer units – fatty acids  Long, straight C chains; -COOH (carboxyl group) at end  Carboxyl group is polar & hydrophilic  Hydrocarbon end is non-polar & hydrophobic Fatty acids with C-C are saturated Fatty acids with 1+ C=C are unsaturated

22 3 Classes of Lipids Triglycerides  3 f.a. joined to a glycerol  Saturated triglycerides have only saturated f.a. Hi mp Solid at RT Shortening, animal fat  Unsaturated triglycerides have some unsaturated f.a. Liquid at RT Plants, seeds, fruit

23 Phospholipids  2 f.a. + glycerol  Structural component of cell membranes (lipid bilayer)  Hydrophobic tail, hydrophilic head Waxes  Long f.a. chain joined to a long alcohol chain  Waterproof molecule; forms protective coating Plant surfaces Earwax Steroids – another important molecule composed of 4 fused C rings with functional groups attached.  Hormones  Cholesterol: precursor to sex hormones, enables nerve & cell function

24 Phospholipids

25 Nucleic Acids Large complex molecules used to store info DNA – deoxyribonucleic acid RNA – ribonucleic acid Monomer unit – nucleotides Nucleotide components:  Phosphate group  5 carbon sugar  Nitrogen base

26 Nucleic Acids

27 Quiz #1 1. What is the energy molecule of a cell? 2. Name the reaction that makes a polymer. 3. Organic compounds contain what element? 4. Adhesion is ___. 5. T/F Water does not dissolve ionic compounds. Bonus – define capillary action

28 Answers #1 1. ATP, adenosine triphosphate 2. condensation rxn 3. C, carbon 4. attractive force between unlike particles 5. F, false B. adhesion/cohesion working together