BIO/PLS 210 Jan Smalle jsmalle@uky Website: Smalle Lab (uky/~jasmal3/)

1. BIO/PLS 210Jan Smallejsmalle@uky.eduWebsite: Smalle Lab(http://www.uky.edu/~jasmal3/)

2. Syllabus

4. Go to: http://www.uky.edu/~jasmal3/ How to download the lectures? Click on: TEACHING PLS 210 Resources Download Lectures

5. PDF file available before (download, print, study…) The lectures Quiz during the lecture Results of the quiz discussed at the beginning of the next lecture

6. PLS/BIO210 Grades distribution over the past 7 years: A: 21% (16-28%) B: 21% C: 28% D: 22% E: 8% (0-13%)

7. The Chemistry of Life Chapter 2

8. David Latimer and his bottle garden

11. Photosynthesis and Respiration Photosynthesis: 6CO2 + 6H2O + energyC6H12O6 + 6O2 Respiration: C6H12O6 + 6O2 6CO2 + 6H2O + energy

12. Atomic Particles

13. Twelve Most Common Elements in Living Organisms

14. hydrogen carbon • Hydrogen has one proton and one electron located in one orbital surrounding the nucleus. • Carbon has six protons and (thus) six electrons. One electron pair is located in the inner orbital. The other four are distributed over four outer orbitals organized in a tetrahedron structure.

15. hydrogen carbon • Carbon has six protons and (thus) six electrons. One electron pair is located in the inner orbital. The other four are distributed over four outer orbitals organized in a tetrahedron structure. • Electrons of the Carbon atom are distributed over two energetically different electron shells.

16. Covalent Bonds • Single bond • Atoms share two electrons • Represented by single line (-) in structural formula H H - C - H H Methane

17. Overall Photosynthesis Reaction 6CO2 + 6H2O + energyC6H12O6 + 6O2 Oxygen Carbon dioxide Water Glucose

18. Overall Photosynthesis Reaction 6CO2 + 6H2O + energyC6H12O6 + 6O2 7 C-O bonds + 5 C-C bonds + 7 C-Hbonds + 5 H-O bonds + 12 O-O bonds 36 covalent bonds 24 C-O bonds + 12 H-O bonds 36 covalent bonds

19. Overall Respiration Reaction C6H12O6 + 6O2 6CO2 + 6H2O + energy 7 C-O bonds + 5 C-C bonds + 7 C-Hbonds + 5 H-O bonds + 12 O-O bonds 36 covalent bonds 24 C-O bonds + 12 H-O bonds 36 covalent bonds

20. hydrogen carbon • Carbon has six protons and (thus) six electrons. One electron pair is located in the inner orbital. The other four are distributed over four outer orbitals organized in a tetrahedron structure. • Electrons of the Carbon atom are distributed over two energetically different electron shells.

21. Electron energy levels Carbon (C) Nitrogen(N) Oxygen (O) Inner shell (Low potential energy) Outer shell (high potential energy) Nucleus Electron Carbon: six protons and six electrons Nitrogen: seven protons and seven electrons Oxygen: eight protons and eight electrons

22. Carbon (C) Carbon (C) Inner shell (Low potential energy) Outer shell (high potential energy) C-C bond

23. Carbon (C) Carbon (C) C-C bond

24. Electron energy levels Carbon (C) Oxygen (O) Inner shell (Low potential energy) Outer shell (high potential energy) Oxygen has 8 protons in its nucleus. The result is a higher positive charge that exerts a stronger attraction force on the electrons of the outer shell. On average, these electrons will be located closer to the nucleus (compared to Carbon).

25. Carbon (C) Oxygen (O) Inner shell (Low potential energy) Outer shell (high potential energy) C-O bond

26. Carbon (C) Oxygen (O) C-O bond? No ! Yes !

27. C-O bond? C O No ! Yes ! • Oxygen has a higher electronegativity than Carbon (Oxygen nucleus has 8 protons compared to 6 in the carbon nucleus. The higher proton number results in a higher positive charge). • Electron pair is pulled towards the O nucleus • Bonding electron pair contains a lower level of potential energy compared to when it is in the middle between nuclei (see waterfall analogy).

28. Waterfall analogy RIVER High potential energy Low potential energy LAKE C C Gravitational force Electrical force High potential energy Low potential energy Electrical force Earth center O C

29. C C O C Carbon-Carbon bonds contain useful energy • Bonding electron pair of C-C contains more energy than C-O pair

30. Hydrogen (H) Carbon (C) Inner shell (Low potential energy) Outer shell (high potential energy) H-C bond

31. Hydrogen (H) Carbon (C) Inner shell (Low potential energy) Outer shell (high potential energy) The potential energy of the bonding electron pair of a H-C bond is defined by the distance to the C nucleus. The distance to the H nucleus is in this case irrelevant since the single electron orbital of the H atom already defines the lowest possible energy state of an electron (or electron pair).

32. H-C bond H-O bond The potential energy of the bonding electron pair of a H-C or H-O bond is defined by the distance to the C or O nucleus. The distance to the H nucleus is in this case irrelevant since the single electron orbital of the H atom already defines the lowest possible energy state of an electron (or electron pair).

33. Carbon-hydrogen bonds contain useful energy H H O C • Bonding electron pair of C-H contains more energy than H-O pair

34. Basis of photosynthesis: Light energy is used to transform C-O and H-O bonds into C-C and H-C bonds C C C C H H C C O O C C H + + Energy + Increased potential energy O Basis of respiration: Energy is liberated by transforming C-C and C-H bonds into C-O and H-O bonds H + + + Energy Decreased potential energy O

35. Photosynthesis and Respiration Photosynthesis: 6CO2 + 6H2O + energyC6H12O6 + 6O2 Respiration: C6H12O6 + 6O2 6CO2 + 6H2O + energy