BIOL 101 Chp 4: Carbon and the Molecular Diversity of Life


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This is a lecture presentation for my BIOL 101 General Biology I students on Chapter 4: Carbon and the Molecular Diversity of Life. (Campbell Biology, 10th Ed. by Reece et al).

Rob Swatski, Associate Professor of Biology, Harrisburg Area Community College - York Campus, York, PA. Email:

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BIOL 101 Chp 4: Carbon and the Molecular Diversity of Life

  1. 1. BIOL 101 General Biology I Chapter 4 Carbon & the Molecular Diversity of Life Rob Swatski Associate Professor of Biology HACC – York Campus 1
  2. 2. Carbon: The Backbone of Life •Living organisms consist mostly of carbon-based compounds •Carbon is unparalleled in its ability to form large, complex, and diverse molecules •Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds 2
  3. 3. Carbon: Life’s Backbone 3
  4. 4. Organic Chemistry C H O N 4
  5. 5. Vitalism 5 the idea that organic compounds arise only in organisms - was disproved when chemists synthesized these compounds
  6. 6. Mechanism 6 the view that all natural phenomena are governed by physical and chemical laws
  7. 7. Organic Molecules and the Origin of Life on Earth •Stanley Miller’s classic experiment demonstrated the abiotic synthesis of organic compounds •Experiments support the idea that abiotic synthesis of organic compounds, perhaps near volcanoes, could have been a stage in the origin of life 7
  8. 8. Water vapor “Atmosphere” Electrode Condenser Cold water Cooled water containing organic molecules Sample for chemical analysis H2O “sea” EXPERIMENT CH4 8
  9. 9. Electron Configuration 9
  10. 10. Valence Hydrogen valence = 1 Oxygen valence = 2 Nitrogen valence = 3 Carbon valence = 4 H O N C 10
  11. 11. 4 valence electrons 4 covalent bonds Tetravalence 11
  12. 12. Valence Electrons of Carbon Tetrahedral 12
  13. 13. Name and Comment Molecular Formula (a) Methane (b) Ethane •CH4 Ball-and- Stick Model Space-Filling Model (c) Ethene (ethylene) •C2H6 •C2H4 Structural Formula 13
  14. 14. Carbon dioxide CO2 Urea CO(NH2)2 O = C = O 14
  15. 15. Carbon Skeletons & Molecular Diversity 15
  16. 16. Ethane Propane 1-Butene 2-Butene Double bonds Rings Cyclohexane Benzene Butane 2-Methylpropane (isobutane) Branching Length 16
  17. 17. Hydrocarbons 17
  18. 18. •Nucleus •Fat droplets (b) A fat molecule (a) Part of a human adipose cell •10 m 18
  19. 19. Isomers Structural Cis-Trans (Geometric) Enantiomers 19
  20. 20. Isomers •Isomers are compounds with the same molecular formula but different structures and properties –Structural isomers have different covalent arrangements of their atoms –Cis-trans (Geometric) isomers have the same covalent bonds but differ in spatial arrangements –Enantiomers are isomers that are mirror images of each other 20
  21. 21. Pentane Structural isomers Cis-Trans (Geometric) isomers 2-methyl butane cis isomer same trans isomer across Enantiomers L isomer D isomer 21
  22. 22. •Enantiomers are important in the pharmaceutical industry •Two enantiomers of a drug may have different effects •Usually only one isomer is biologically active •Differing effects of enantiomers demonstrate that organisms are sensitive to even subtle variations in molecules 22
  23. 23. Dr. George Cotzias 1967 23
  24. 24. Enantiomers L-dopa D-dopa inactive active 24
  25. 25. Drug Ibuprofen Albuterol Condition Pain, inflammation Asthma Effective Enantiomer S-Ibuprofen R-Albuterol R-Ibuprofen S-Albuterol Ineffective Enantiomer 25
  26. 26. The Chemical Groups Most Important in the Processes of Life •Functional groups are the components of organic molecules that are most commonly involved in chemical reactions •The number and arrangement of functional groups give each molecule its unique properties 26
  27. 27. Functional groups Estradiol Testosterone 27
  28. 28. Na+ Na+ Na+ Ca++ Ca++ Ca++ Ca++ 28
  29. 29. 7 Major Functional Groups Hydroxyl group Carbonyl group Carboxyl group Amino group Sulfhydryl group Phosphate group Methyl group 29
  30. 30. STRUCTURE EXAMPLE Alcohols -Their specific names usually end in -ol. (may be written HO—) Ethanol Is polar as a result of the electrons spending more time near the electronegative oxygen atom. Can form hydrogen bonds with water molecules, helping dissolve organic compounds such as sugars. Hydroxyl 30
  31. 31. Carbonyl STRUCTURE EXAMPLE Ketones if the carbonyl group is within a carbon skeleton Aldehydes if the carbonyl group is at the end of the carbon skeleton A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal. Acetone Propanal Ketone and aldehyde groups are also found in sugars, giving rise to two major groups of sugars: ketoses (containing ketone groups) and aldoses (containing aldehyde groups). 31
  32. 32. Carboxyl Acetic acid Carboxylic acids (organic acids) Polar covalent bond Carboxylate ion (-1) Acetic acid Acetate ion 32
  33. 33. Amino Amino acid Amines +1 Base (ionized) (nonionized) Glycine 33
  34. 34. Sulfhydryl Cysteine S-containing amino acid Thiols Cross-linking covalent bonds Protein shape 34
  35. 35. Phosphate Chemical reactions Phospholipid backbone Glycerol phosphate Organic phosphates -2 or -1 charge 35
  36. 36. Methyl DNA structure 5-Methyl cytidine Methylated compounds Gene expression Hormone function 36
  37. 37. ATP: An Important Source of Energy for Cellular Processes •One phosphate molecule, adenosine triphosphate (ATP), is the primary energy-transferring molecule in the cell •ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups 37
  38. 38. ATP Adenosine triphosphate Adenosine 38
  39. 39. Adenosine Triphosphate (ATP) Primary source of chemical potential energy Powers muscle contraction, chemical transport, organelle movement Adenine, ribose, and 3 phosphate groups 39
  40. 40. 40
  41. 41. •Energy P P P P i P P Adenosine Adenosine ADP ATP Reacts with H2O •Energy 41
  42. 42. ATP Cycle P i ADP + H2O ATP + ATP ATP hydrolysis ATP synthesis 42
  43. 43. 43
  44. 44. 44