1. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Got Lactase? Many people in the world suffer from lactose intolerance –Lacking an enzyme (lactase) that digests lactose, a sugar found in milk –“ase” = enzyme –“ose” = sugar CARBON COMPOUNDS ORGANIC CHEMISTRY

2. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Lactose intolerance illustrates the importance of biological molecules –To the functioning of living cells and to human health –The atoms carbon (C), hydrogen (H), oxygen (O) and nitrogen (N) make up molecules that support life

3. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Lipids Fats/Oils/Steroids/Wax 4 Categories of Organic Molecules Molecules of Life Biochemicals (CHON) Proteins Enzymes/Structure/ Movement/Protection Nucleic Acids (DNA/RNA) Carbohydrates Glucose/Fructose Starch/Cellulose

4. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings All compounds are either organic, containing carbon bonded to hydrogen and oxygen or inorganic. The chemistry of carbon is the chemistry of life. Structural formula Methane H H H H H H H H Ball-and-stick model Space-filling model C C The 4 single bonds of carbon point to the corners of a tetrahedron. HYDROCARBONS

5. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings I.Carbon bonding: Has 4 electrons in outer energy level Atoms are most stable with 8 electrons in outer shell Carbon forms bonds with other atoms, including carbon 6P 6N

6. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings I. Carbon bonding: Single Bond Represents 2 electrons Double Bond Represents 4 electrons Triple Bond Represents 6 electrons

7. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Cells make a huge number of large molecules from a small set of small molecules The four main classes of biological molecules –Are carbohydrates, lipids, proteins, and nucleic acids Many of the molecules are gigantic –And are called macromolecules

8. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Cells make most of their large molecules –By joining smaller organic molecules into chains called polymers Cells link monomers to form polymers –By dehydration synthesisdehydration synthesis H OHH H OHOH Unlinked monomer Dehydratio n reaction Longer polymer Short polymer OH H H Unlinked monomer Dehydration reaction Short polymer H2OH2O

9. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Polymers are broken down to monomers –By the reverse process, hydrolysis Animation: Hydrolysis of sucroseHydrolysis of sucrose H H2OH2O OH H H Hydrolysis

10. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings VI. Molecules of Life A. Carbohydrates- main source of energy for cells Monosaccharides are the simplest carbohydrates The carbohydrate monomers are monosaccharides A monosaccharide has a formula that is a multiple of CH 2 O ( the ratio 1:2:1) –And contains hydroxyl groups and a carbonyl group

11. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The monosaccharides glucose and fructose are isomers –That contain the same atoms but in different arrangements –Monosaccharides can also occur as ring structures C C C C C C C C C C H H H H H H H H H H H HO H H H C O OH CO Glucose Fructose

12. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Monosaccharides can join to form disaccharides –Such as sucrose (table sugar) and maltose (brewing sugar) –Polysaccharides are long chains of sugar units Polysaccharides are polymers of monosaccharides –Linked together by dehydration reactions H H H H H H H H H H H H H H H H H H H H OH HO O O O OH CH 2 OH H2OH2O OH HO O OH O H Glucose Maltose O OH Polysaccharide - starch

13. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Starch and glycogen are polysaccharides –That store sugar for later use Cellulose is a polysaccharide found in plant cell walls – provides structure Starch granules in potato tuber cells Glycogen granules in muscle tissue Cellulose fibrils in a plant cell wall Glucose monomer Cellulose molecules STARCH GLYCOGEN CELLULOSE O O O O OOO O OOO O O O O O O O O O O O O O O O O O O O O O OO OOOOO O O OO O OO O OH Figure 3.7

14. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings B. LIPIDS Fats are lipids that are mostly energy-storage molecules Lipids are diverse compounds –That consist mainly of carbon and hydrogen atoms linked by nonpolar covalent bonds –Hydrophobic –water fearing Insulation- thermal & electrical

15. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Fats, also called triglycerides –Are lipids whose main function is energy storage –Consist of glycerol linked to three fatty acids –Saturated – no double bonds (solid room temp.) –Unsaturated - has double bonds (liquid room temp.) CH 2 CH 3 H2OH2O H H H H OH H HO C O C C C Fatty acid Glycerol H HH HH CH 2 OO O CH 3 CH 2 CH 3 CH 2 CH CH 2 CH 3 CCC O OO CC C H Unsaturated Fat

16. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Phospholipids, waxes, and steroids are lipids with a variety of functions Phospholipids are a major component of cell membranes (phospholipid bilayer) Waxes form waterproof coatings (cuticle on leaf) Steroids are often hormones (anabolic steroids - synthetic)

17. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings What are trans fats and why are they such a big deal? Twinkie Video

18. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings C. PROTEINS Proteins are essential to the structures and activities of life A protein –Is a polymer constructed from amino acid monomers –Transport substances and fight disease (antibodies) –As enzymes they regulate chemical reactions

19. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Proteins are made from amino acids linked by peptide bonds Proteins are based on different arrangements of a common set of 20 amino acid monomers Each amino acid contains –A carboxyl group –An amino group –And an “R” group which makes it unique H H N H C R C O OH Amino group Carboxyl (acid) group

20. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Cells link amino acids together –By dehydration synthesis The bonds between amino acid monomers –Are called peptide bonds H H NCC O OH H H N+C H R C O H2OH2O H H NCCNC C R HR O Peptide bond Dipeptide Amino acid Dehydration reaction Amino group H R Amino acid Carboxyl group HO H

21. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Groove A protein’s specific shape determines its function A protein consists of one or more polypeptide chains –Folded into a unique shape that determines the protein’s function

22. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings A protein’s shape depends on four levels of structurelevels of structure 1.Primary Structure Is the sequence of amino acids forming its polypeptide chains 2. Secondary structure Is the coiling or folding of the chain, stabilized by hydrogen bonding 3. Tertiary Structure Is the overall three dimensional shape of a polypeptide 4. Quaternary Structure Results from the association of two or more polypeptide chains

23. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Primary Structure Levels of Protein Structure Primary structure Gly Thr Gly Glu SerLys Cys Pro LeuMet Val Lys Val Leu Asp AlaVal Arg Gly Ser Pro Ala Ile Asn Val Ala Val His Val Amino acids Phe Arg Secondary structure C N O C C N H O C C H Hydrogen bond O C N H C C O N H O C C N H C N O C C N H O C C N H C O C H N H C O H C R H N Alpha helix C N H C C H H O N R CC O N H O C C N H CC O N H O C C N H C O C N H O C CN H C O O C C N H C C O N H C C O N H C C O N H C C O N H C C O N H C C O N H C C O H N C Pleated sheet Amino acids Secondary structure Tertiary structure Polypeptide (single subunit of transthyretin) Tertiary Structure Quaternary structure Transthyretin, with four identical polypeptide subunits Quaternary Structure

24. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings D. NUCLEIC ACIDS Examples of nucleic acids include deoxyribonucleic acid (DNA) and ribonucleic (RNA) –Serve as the code for building proteins and thus control the life of a cell The monomers of nucleic acids are nucleotides –Nucleotides are composed of a 5-carbon sugar, phosphate group, and nitrogenous base Sugar OH OPO OO CH 2 H O HH OHH H N N H N N H HH N Phosphate group Nitrogenous base (A)

25. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings DNA and RNA –Stretches of a DNA molecule called genes make specific proteins –DNA programs the amino acid sequences of proteins. DNA is double-stranded forming a helix –RNA is a single-stranded polynucleotide