CHAPTER 2 CHEMISTRY OF LIFE

Level of organisation  ATOM  MOLECULE  ELEMENT  COMPOUND  SOLUTION Water

 Only 4 of the 90 elements make up more than 96% of the mass of the human body. They are: Carbon (C) Hydrogen (H) Oxygen (O) Nitrogen (N)

Mixture and Solutions  When elements combine to form a compound, the elements no longer have their original properties.  A mixture is a combination of substance in which the individual components retain their properties. Ex: Sand and sugar

 A solution is mixture in which one or more substances (solute) are distributed evenly in another substance (solvent). Ex: Kool-aid  *The concentration of solute is important to organisms  A suspension is a mixture of water and nondissolved materials

Acids and Bases  Chemical reactions can occur only when conditions are right; they depend on the pH of the environment  pH is a measure of how acid or basic (alkaline) a solution is  A scale with values ranging from 0 to 14 is used to measure pH

 ACID is any substance that forms hydrogen ions (H+) in water. Ex: HCl (H+) and (Cl-) has a pH of below 7  BASE is any substance that forms hydroxide ions (OH-) in water. Ex: NaOH (Na+) & (OH-) has a pH above 7 H+OH-

 Buffers=dissolved compounds that control pH in the body ( HOMEOSTASIS)  Buffers are weak acids or bases that can react with strong acids or bases to prevent sharp sudden changes in pH.

Importance of Acids and Bases to Biological Systems  Chemical reactions in organisms depend on the pH of the environment Ex: Pepsidase is an enzyme that works best in the acidic human stomach

 Certain organisms require a certain pH environment for optimum (best) growth Organism A__________ Organism B

Life Substances 1.Organic compounds are derived from living things and contain Carbon, must have Carbon and Hydrogen to be organic 2.Inorganic compounds are derived from nonliving things (ex: Water, Carbon Dioxide)

 Carbon compounds: easily form 4 covalent bonds to create chains, rings, or branches

Polymerization: when a large compound (polymer) is produced from smaller compounds (monomers) as the smaller compounds are joined together. Macromolecules: large polymers

 Condensation Reaction (dehydration synthesis) to make or build, water is produced  Hydrolysis to split, water is added

1.Carbohydrates 2.Lipids 3.Proteins 4.Nucleic Acids

Carbohydrates  Composed of C (Carbon), Hydrogen (H), Oxygen (O) in approximate ratio 1:2:1

Monosaccharide: single (simple) sugar Molecular formula for all 3: C 6 H 12 O 6  GLUCOSE-Produced by plants through photosynthesis  FRUCTOSE-found in fruits  GALACTOSE-found in milk

Disaccharides formed by 2 sugars C 12 H 22 O 11  Sucrose = glucose + Fructose  Maltose = glucose + Glucose  Lactose = glucose + Galactose

Polysaccharides formed by more than 2 sugars  Starch-storage for plants  Glycogen-storage for animals (liver)  Cellulose-cell wall of plants  Chitin=cell wall of fungi

 What makes them different from one another is the arrangement of the individual atoms (structural formulas)  Isomers – compounds that differ in structure but nor in molecular composition

Synthesis of Dissachharides GlucoseFructoseSucroseWater + + C 6 H 12 O 6 C 12 H 22 O 6 H2OH2O + + * Dehydration synthesis-water is squeezed out ++

Hydrolysis of Disaccharide Water Sucrose FructoseGlucose C 6 H 12 O 6 C 12 H 22 O 6 H2OH2O * Hydrolysis-water is added

Lipids: Fatty Compounds  Made of C, H, O w/ a greater # in C:H atoms and a smaller # of O atoms than carbohydrates (No uniform Ratio)  Ex: fats, oils, waxes (do Not dissolve in water)

Many common lipids are constructed of a unit of: Glycerol (3-Carbon Alcohol) combined by dehydration synthesis 3 fatty acids-hydrocarbon chain with an Carboxyl Group -COOH

 Hydrophilic End (water loving-carboxyl end that is polar)  Hydrophobic End (water fearing- hydrocarbon end that is nonpolar)

 Functions: forms much of cell membrane to serve as a barrier between the inside and outside of the cell – energy storage for cells  Ex: waxes, triglycerides

Proteins: Organic Compounds made of C, H, O, N  Polymer made of amino acids (monomers); organisms have thousands of proteins

Amino Acids: 20 different kinds that form proteins-has 5 Groups: a) Central C atom b) Single H atom c) Carboxyl Group (COOH) d) Amine Group (NH 2 ) e) R Group (repeating CH 2 + CH 2 of different lengths)

Dipeptide: 2 amino acids bound together covalently by condensation reaction (a molecule of H 2 O is lost)- held together by peptide bonds a)c) e) d) b) Amino acid Dipeptide Water

Polypeptide:  A long chain of amino acids held together by peptide bonds  Ex of Proteins: Insulin (hormone), hemoglobin, and enzymes

Nucleic Acids: complex organic molecules that store important information in the cell  2 important types of nucleic acids are DNA and RNA 1.DNA (deoxyribonucleic acid): stores essential info for almost all cell activities-including cell division 2.RNA (ribonucleic acid): stores and transfers info for proteins

Nucleotides: monomers that make up both DNA & RNA-made up of 3 main components:  Phosphate Group  Five-Carbon Sugar  Nitrogen Base (ring)