The Chemistry of Life

1. The Chemistry of Life

2. Why are we studying chemistry? Chemistry is the foundation of Biology

3. Everything is made of matter • Matter is made of atoms Hydrogen 1 proton 1 electron Oxygen 8 protons 8 neutrons 8 electrons Proton + Neutron 0 Electron –

4. The World of Elements H C N O Na Mg P S K Ca Different kinds of atoms = elements

5. Life requires ~25 chemical elements • About 25 elements are essential for life • Four elements make up 96% of living matter: • carbon (C) • hydrogen (H) • oxygen (O) • nitrogen (N) • Four elements make up most of remaining 4%: •phosphorus (P)•calcium (Ca) •sulfur (S) •potassium (K)

6. Compounds • The atoms form compounds • Chemical Bonds • Able to form large complicated molecules (Highly Organized) • Simple to Highly complicated. • Carbohydrates • Lipids - Fats • Proteins • Nucleic Acids - DNA, RNA Whew, That’s Lots-O- Energy to Make and Lots-O-Energy released When Broke!

7. Molecules • Atoms combine to make molecules • Chemical Reactions • When atoms are reorganized into different substances • Endogonic • Takes energy to build • Energy IN • Exogonic • Breaks down to release E • Energy OUT

8. Reactants and Products • Reactants are what you start with • Products are what you end with • Every reaction has to be balanced!! • What goes in must come out!! • Endogonic • Energy In - More energy in the products • Exogonic • Energy out - Less Energy in the products ATP!

9. Flow of energy through life • Life is built on chemical reactions • transforming energy from one form to another organic moleculesATP & organic molecules sun organic moleculesATP & organic molecules solar energyATP& organic molecules

10. Chemical reactions & energy • Some chemical reactions release energy • exogonic • Breaking down big molecules • Spontaneous • Some chemical reactions require input of energy • endogonic • Building big molecules • Need an input of energy digesting molecules= LESS organization=lower energy state building molecules= MORE organization=higher energy state

11. Endogonic vs. Exogonic reactions exogonic endogonic - energy released - digestion • energy invested • synthesis Products have LESS E than Reactants! +G -G Products have More E than Reactants! G = change in free energy = ability to do work

12. Energy & life • Organisms require energy to live • where does that energy come from? • Energy Couplingexogonic reactions (releasing energy) powers endogonic reactions (needing energy) energy + + digestion synthesis energy + +

13. What drives reactions? • If exogonic reactions are “downhill”, why don’t they just happen spontaneously? • because bonds are stable bonds Why don’tstable polymersspontaneouslydigest into theirmonomers? starch EA

14. energy Activation energy • Breaking down large molecules requires an initial input of energy • Activation energy • large biomolecules are stable • must absorb energy to break bonds cellulose CO2 + H2O + heat

15. Too much activation energy for life • Activation energy • amount of energy needed to destabilize the bonds of a molecule • moves the reaction over an “energy hill” Whoa there Cowboy! Not That Much Activation E! glucose

16. Catalysts • So what’s a cell got to do to reduce activation energy? • get help! … chemical help… ENZYMES Call in the ENZYMES! G

17. energy How Does it Work?

18. Enzymes • Biological catalysts • Proteins • facilitate chemical reactions • increase rate of reaction without being consumed • By reducing activation energy • Can’t make a nonspontaneous rx. spontaneous • Required for all biological reactions • highly specific • thousands of different enzymes in cells • control reactionsof life

19. Enzymes vocabulary substrate • reactant which binds to enzyme • enzyme-substrate complex: temporary association product • end result of reaction active site • enzyme’s catalytic site; substrate fits into active site active site products substrate enzyme

20. Properties of enzymes • Reaction specific • each enzyme works with a specific substrate • chemical fit between active site & substrate • Bazillions of different types of enzymes in your Body • Not consumed in reaction • single enzyme molecule can catalyze thousands or more reactions per second • enzymes unaffected by the reaction • Affected by cellular conditions • any condition that affects protein structure • temperature, pH, salinity

21. Naming conventions • Enzymes named for reaction they catalyze • End in Ase • sucrase breaks down sucrose • proteases break down proteins • lipases break down lipids • DNA polymerase builds DNA • adds nucleotides to DNA strand • SethBlackkickasease • GET IN LINE!!

23. More about Water Why are we studying water? All life occurs in water • inside & outside the cell

24. Chemistry of water • H2O molecules form H-bonds with each other • +H attracted to –O • creates a sticky molecule

25. Elixir of Life • Special properties of water 1. cohesion & adhesion • surface tension, capillary action 2. good solvent • many molecules dissolve in H2O • hydrophilic vs. hydrophobic 3. lower density as a solid • ice floats! 4. high specific heat • water stores heat 5. high heat of vaporization • heats & cools slowly Ice!I could use more ice!

26. 1. Cohesion & Adhesion • Cohesion • H bonding between H2O molecules • water is “sticky” • surface tension • drinking straw • Adhesion • H bonding between H2O & other substances • capillary action • meniscus • water climbs uppaper towel or cloth Try that with flour…or sugar…

27. How does H2O get to top of trees? Transpiration is built on cohesion & adhesion Let’s go to the videotape!

28. 2. Water is the solvent of life • Polarity makes H2O a good solvent • polar H2O molecules surround + & –ions • solvents dissolve solutes creating solutions

29. What dissolves in water? • Hydrophilic • substances have attraction to H2O • polar or non-polar?

30. What doesn’t dissolve in water? • Hydrophobic • substances that don’t have an attraction to H2O • polar or non-polar? Oh, lookhydrocarbons! fat (triglycerol)

31. 3. Density Anomaly - The special case of ice • Most (all?) substances are more dense when they are solid, but not water… • Ice floats! • H bonds form a crystal

32. Ice floats

33. Why is “ice floats” important? • Oceans & lakes don’t freeze solid • surface ice insulates water below • allowing life to survive the winter • if ice sank… • ponds, lakes & even oceans would freeze solid • in summer, only upper few inches would thaw

34. 4. Specific heat • H2O resists changes in temperature • high specific heat • takes a lot to heat it up • (heat absorbed to break H bonds) • takes a lot to cool it down • (heat is released when H bonds form) • H2O moderates temperatures on Earth • Lots of ecological effects

35. Specific heat& climate

36. Evaporative cooling 5. Heat of vaporization Organisms rely on heat of vaporization to remove body heat

37. Ionization of water & pH • Water ionizes • H+ splits off from H2O, leaving OH– • if [H+]= [-OH], water is neutral • if [H+]> [-OH], water is acidic • if [H+]< [-OH],water is basic • pH scale • how acid or basic solution is • 1  7  14 H2O  H+ + OH–

38. H+ Ion Concentration Examples of Solutions pH 100 0 Hydrochloric acid 10–1 1 10–2 2 Stomach acid, Lemon juice Vinegar, cola, beer 10–3 3 Tomatoes 10–4 4 10–5 5 Black coffee, Rainwater 10–6 6 Urine, Saliva 7 Pure water, Blood 10–7 Seawater 8 10–8 Baking soda 10–9 9 Great Salt Lake 10–10 10 10–11 Household ammonia 11 10–12 12 Household bleach 10–13 13 Oven cleaner 10–14 14 Sodium hydroxide pH Scale tenfold changein H+ ions pH1  pH2 10-1 10-2 10 times less H+ pH8  pH7 10-8 10-7 10 times more H+ pH10  pH8 10-10 10-8 100 times more H+

39. 9 8 7 6 Buffering range 5 pH 4 3 2 1 0 0 1 2 3 4 5 Amount of base added Buffers & cellular regulation • pH of cells must be kept ~7 • pH affects shape of molecules • shape of molecules affect function • pH affects cellular function • Control pH by buffers • reservoir of H+ • donate H+ when [H+] falls • absorb H+ when [H+] rises

40. He’s gonnaearn a Darwin Award! AnyQuestions? Do one brave thing today…then run like hell!