Chapter 9 : Cellular Respiration and Fermentation

1. Chapter 9:Cellular Respiration and Fermentation

2. Essential Knowledge • 2.a.1 – All living systems require constant input of free energy (9.1-9.5). • 2.a.2 – Organisms capture and store free energy for use in biological processes (9.1-9.5).

3. Cellular Respiration - Preview • Def - The process of releasing energy/ATP from food • Food - Stored energy in chemical bonds (provides fuel) • ATP - Useable energy for cellular processes • Wastes – CO2 and H2O • Mitochondrion store most of equipment needed for rxn

4. Respiration (Rs) - Equation C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy (ATP or heat) • Rxn is spontaneous (-∆G) • The energy is released (exergonic) from the bonds in the org molecules • Remember: Org molecules store energy in their arrangement of atoms • Org molecules can be carbs, proteins or fats/lipids

6. Focus of Chapter Cellular Rs • Purpose- what is the reaction suppose to do for the cell? • Location- where does it occur? • Requirements - what is needed to make it run? • Products- what does it produce? Other • Fermentation, Redox

7. Fuel? What is used? • Organic molecules with a large amt of hydrogen make great fuel! Why? • H becomes oxidized (only has one e-) very easily and energy is released • Remember: Carbs, fats, proteins are storage bins for e- associated with hydrogen

8. Oxidation - definitions • Loss of electrons • Lossof energy • Lossof hydrogens from carbons • Ex:Na+ (of NaCl)

9. Food and Oxidation • Food (organic molecules) contain a lot of H atoms • These serve as great long-term fuels • Why? • Because H becomes easily oxidized (releases energy frequently)

10. Reduction - definitions • Gain of electrons (REDUCING + charge) • Gainof energy • Gain of hydrogens to carbons • Ex: O is often reduced! • Why? • Because electrons are pulled closer to O

11. Redox reactions

12. Equation for Rs Oxidized C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy (ATP/heat) General Redox Equation: Xe- + Y  X + Ye- Reduced

13. Redox reactions • Involves transfer of e- and energy release • Sometimes doesn’t involve complete transfer • Red and Oxd reactions are usually paired or linked together. • Why?Becausee- transfer requires donor and acceptor • Many of the reactions will be done by phosphorylation • Redox video

14. Phosphorylation • Adding a phosphate group to a molecule • Ex: ATP cycle (add P to ADP = ATP) • Two types: • Oxidative AND substrate-level • The phosphate group adds “energy” to the molecule for chemical reactions (think ATP cycle) • Endergonicrxn

15. Phosphorylation

16. Cell Respiration – 3 parts 1. Glycolysis 2. Krebs Cycle 3. Electron Transport Chain **Use page 167 as a starting point: Cellular Respiration - A Preview

18. Glycolysis STEP 1 • Glyco- glucose -lysis: to split • Formula for glucose: C6H12O6 • Universal step in all Rs types. • Likely the earliest type of cell energy processes • Overview: • Glucose splits into 2 3-C sugars (then oxidizes to form pyruvate)

19. Glycolysis • Function- To split glucose and produce NADH and ATP • ATP made by substrate-levelphosphorylation • Enzyme transfers phosphate group from substrate/reactant to ADP to make ATP • Location– Cytoplasm of the cell

21. Electron Carrier Compounds • Molecules that transport or shuttle electrons within the cell • Exist in two forms: • Oxidized (ox) • Reduced (red) • Ex: NAD and FAD

22. NAD • Nicotinamide Adenine Dinucleotide • NAD+ + 2 e- NADH • NAD+ = oxidized form • NADH = reduced form* *Reduced by e- from food oxidation

24. Glycolysis Requirements • Glucose • 2 ATP • 4 ADP • 2 NAD+ • Can occur with or without O2

25. Glycolysis Intro Glycolysis - Products • 2 Pyruvic Acids (a 3-Carbon acid) • 2 ADP, 4 ATP, 2 NADH • NET RESULT: • 2 ATP per glucose • 2 NADH • 2 pyruvate • H2O Notice:NoCO2 made during this step!

27. Krebs Cycle STEP 2 • Oxidizes fuel from pyruvate molecules • Remember? Pyruvate formed during glycolysis • Also called: • Citric Acid Cycle • Tricarboxylic Acid Cycle

28. Krebs Cycle • Function: Oxidize pyruvicacid (to make CO2 ) • Produces: NADH and FADH2 • Location: Mitochondria matrix • Before Krebs: Acetyl CoA must be formed • Acetyl CoA is needed to actually start Krebs

29. Pyruvatemoved into mito? • Why? How? • Pyruvate is moved into mitochondria (from cytoplasm) • Why? This is where the 2nd step occurs (specific enzymes are in mito) • Serves as a checkpoint • Uses active transport and transport proteins. • Why? Pyruvateis a charged molecule!

30. Formation of Acetyl CoA

31. Krebs Cycle Requirements • Pyruvic acid (3C acid) • Acetyl coenzyme A • 4 NAD+ • 1 ADP • 1 FAD • Double this list for each glucose

32. Krebs Cycle Products • Krebs Cycle Intro • 3 CO2 • Acetyl CoA • 4 NADH • 1 FADH2 • 1 ATP • Double this list for each glucose Made from pyruvate LOADS of energy stored in these molecules

34. Krebs Cycle notes • Notice: • Only 1 ATP made per cycle • Produces most of the cell's energy in the form of NADH and FADH2 • Does NOT require O2

35. Comment about ATP • The ATPs produced directly in Krebs Cycle and Glycolysisare by: • Substrate-level phosphorylation • The P group is transferred from a substrate to ADP • Making ATP

36. At this point… • After the Krebs and glycolysis cycles, the cell has made a total of 4 ATP. • Remember: some ATP had to be used to power the cycles. • Most energy (at this point) comes from NADH and FADH2

37. Electron Transport System STEP 3 • ETC/S or Electron Transport Chain • This is a collection of proteins that are structurally linked • Located in inner membrane of mito • Folding of mito(cristae) allows for lots of places (large surface area!) for ETC to occur

38. ETC/S • Uses sets of Cytochromes • Fe (Iron)-containing proteins to pass electrons • The Cytochromes alternate between Red and Ox forms and pass electrons down to O2 • Remember: LEO, GER; LEO the lion goes GER • Losing Electrons is Oxidation; Gaining Electrons is Reduction

39. As e- moves down the ETC, free energy decreases

40. ETC/S • Function: Convert NADH and FADH2 into ATP • Location: Mitochondria cristae/folds

41. ETC Requirements • NADH or FADH2 • ADP • O2 • We finally see the need/requirement of Oxygen

42. ETC Products • NAD+ and FAD • ATP (LOTS!!!) • H2O • Remember: Water was also produced during glycolysis ETC explanation

43. ETC - ATP Yields • Each NADH  3 ATP • Each FADH2 2 ATP • TOTAL: 34 ATP

44. Chemiosmotic Hypothesis • ETC energy is used to move H+ (protons) across the mito/cristae membrane • ATP is generated as the H+ diffuse back into the matrix

46. ATP Synthase Enzyme • An enzyme that uses the flow of H+ to make ATP • Works like an ion pump in reverse, or like a waterwheel under the flow of H+ “water” • Power source: • H+ concentration difference on opposite sides of mitochondrial membrane

47. Oxidative Phosphorylation • ATP synthase uses oxidative phosphorylation to make ATP during ETC • Uses H ions to make ATP and water (using Oxygen)

48. ATP Synthase

49. Alcoholic Fermentation • Done by yeast • A kind of fungus • Used in brewing beer, winemaking, and baking • CO2 bubbles generated give: • Bread a rising effect • Wine/Beer the carbonated effect

50. Alcoholic Fermentation • Uses only Glycolysis • An incomplete oxidation - energy is still left in the products (alcohol) • Does NOT require O2 • Produces ATP (when O2 is not available)