1. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Chapter 3 The Molecules of Cells

2. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Got Lactose? Many people in the world suffer from lactose intolerance –Lacking an enzyme that digests lactose, a sugar found in milk

3. 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

4. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings INTRODUCTION TO ORGANIC COMPOUNDS 3.1 Life’s molecular diversity is based on the properties of carbon A carbon atom can form four covalent bonds –Allowing it to build large and diverse organic compounds 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. Figure 3.1A

5. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Carbon chains vary in many ways Figure 3.1A

6. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Hydrocarbons –Are composed of only hydrogen and carbon Some carbon compounds are isomers –Molecules with the same molecular formula but different structures

7. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 3.2 Functional groups help determine the properties of organic compounds Examples of functional groups Table 3.2

8. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Functional groups are particular groupings of atoms –That give organic molecules particular properties Female lion Estradiol HO OH O Testosterone Figure 3.2 Male lion

9. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 3.3 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

10. 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 a dehydration reaction H OHH H OHOH Unlinked monomer Dehydratio n reaction Longer polymer Short polymer OH H H Unlinked monomer Dehydration reaction Short polymer H2OH2O Figure 3.3A

11. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Polymers are broken down to monomers –By the reverse process, hydrolysis H H2OH2O OH H H Hydrolysis Figure 3.3B

12. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CARBOHYDRATES 3.4 Monosaccharides are the simplest carbohydrates The carbohydrate monomers –Are monosaccharides Figure 3.4A

13. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings A monosaccharide has a formula that is a multiple of CH 2 O –And contains hydroxyl groups and a carbonyl group

14. 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 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 Figure 3.4B

15. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Monosaccharides can also occur as ring structures H H H H H H H H H H O C C CC O OH HO OH CH 2 OH C OH O Structural formula Abbreviated structure Simplified structure 6 5 4 3 2 1 Figure 3.4C

16. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 3.5 Cells link two single sugars to form disaccharides Monosaccharides can join to form disaccharides –Such as sucrose (table sugar) and maltose (brewing sugar) 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 Figure 3.5

17. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 3.6 How sweet is sweet? Various types of molecules, including nonsugars –Taste sweet because they bind to “sweet” receptors on the tongue Table 3.6

18. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 3.7 Polysaccharides are long chains of sugar units Polysaccharides are polymers of monosaccharides –Linked together by dehydration reactions

19. 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 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

20. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings LIPIDS 3.8 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

21. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Lipids are grouped together –Because they are hydrophobic Figure 3.8A

22. 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 CH 2 CH 3 H2OH2O HH HH OH H HO CO C CC 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 Figure 3.8BFigure 3.8C

23. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 3.9 Phospholipids, waxes, and steroids are lipids with a variety of functions Phospholipids are a major component of cell membranes Waxes form waterproof coatings Steroids are often hormones HO CH 3 H3CH3C Figure 3.9

24. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 3.10 Anabolic steroids pose health risks Anabolic steroids –Are synthetic variants of testosterone –Can cause serious health problems

25. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PROTEINS 3.11 Proteins are essential to the structures and activities of life A protein –Is a polymer constructed from amino acid monomers

26. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Proteins –Are involved in almost all of a cell’s activities As enzymes –They regulate chemical reactions. Figure 3.11

27. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 3.12 Proteins are made from amino acids linked by peptide bonds Protein diversity –Is based on different arrangements of a common set of 20 amino acid monomers

28. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Each amino acid contains –An amino group –A carboxyl group –An R group, which distinguishes each of the 20 different amino acids H H N H C R C O OH Amino group Carboxyl (acid) group Figure 3.12A

29. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Each amino acid has specific properties –Based on its structure H H N H C CH 2 CH CH 3 C O OH H H NC H CH 2 OH C O H H NC H C O CH 2 C OHO Leucine (Leu)Serine (Ser)Aspartic acid (Asp) HydrophobicHydrophilic Figure 3.12B

30. 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 Figure 3.12C

31. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Groove Figure 3.13BFigure 3.13A 3.13 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

32. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 3.14 A protein’s shape depends on four levels of structure

33. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Primary Structure A protein’s primary structure –Is the sequence of amino acids forming its polypeptide chains 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 Figure 3.14A

34. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Secondary structure A protein’s secondary structure –Is the coiling or folding of the chain, stabilized by hydrogen bonding Figure 3.14B 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 C C O N H O C C N H C C O N H O C C N H C O C N H O C C N 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

35. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Tertiary Structure A protein’s tertiary structure –Is the overall three-dimensional shape of a polypeptide Tertiary structure Polypeptide (single subunit of transthyretin) Figure 3.14C

36. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Quaternary Structure A protein’s quaternary structure –Results from the association of two or more polypeptide chains Quaternary structure Transthyretin, with four identical polypeptide subunits Figure 3.14D Polypeptide chain Collagen

37. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings TALKING ABOUT SCIENCE 3.19 Linus Pauling contributed to our understanding of the chemistry of life Linus Pauling made important contributions –To our understanding of protein structure and function Figure 3.15

38. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings NUCLEIC ACIDS 3.20 Nucleic acids are information-rich polymers of nucleotides Nucleic acids such as DNA and RNA –Serve as the blueprints for proteins and thus control the life of a cell

39. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The monomers of nucleic acids are nucleotides –Composed of a sugar, phosphate, and nitrogenous base Sugar OH OPO OO CH 2 H O HH OH H H N N H N N H HH N Phosphate group Nitrogenous base (A) Figure 3.16A

40. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The sugar and phosphate –Form the backbone for the nucleic acid or polynucleotide Sugar-phosphate backbone T G C T A Nucleotide Figure 3.16B

41. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings DNA consists of two polynucleotides –Twisted around each other in a double helix C TA GC CG T A CG AT A G C A T AT T A Base pair T Figure 3.16C

42. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings RNA, by contrast –Is a single-stranded polynucleotide

43. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Stretches of a DNA molecule called genes –Program the amino acid sequences of proteins