1. Cellular Respiration

2. Autotrophs Autotrophs are organisms that can use basic energy sources (i.e. sunlight) to make energy containing organic molecules from inorganic raw materials. 2 Types Photosynthetic autotrophs Chemosynthetic autotrophs

3. Chemosynthesis Chemosynthesis is a process used by prokaryotic organisms to use inorganic chemical reactions as a source of energy to make larger organic molecules.

4. Heterotrophs Heterotrophs require organic molecules as food. They get their energy from the chemical bonds in food molecules such as carbohydrates, fats, and proteins.

5. Prokaryotic Cells

6. Prokaryotic cells have no nuclei. Prokaryotic cells lack mitochondria and chloroplasts. They carry out photosynthesis and cellular respiration within the cytoplasm or on the inner surfaces of the membranes.

7. Eukaryotic Cells

8. Eukaryotic cells contain nuclei, mitochondria, and in the case of plant cells chloroplasts. Plant cells, animal cells, fungi and protists are all eukaryotic.

9. Cellular Respiration Cellular respiration is the controlled release of chemical-bond energy from large, organic molecules. This energy is utilized for many activities to sustain life. Both autotrophs and heterotrophs carry out cellular respiration.

10. Aerobic Vs. Anaerobic Aerobic respiration requires oxygen. Anaerobic respiration does not require oxygen.

11. Aerobic Respiration Aerobic cellular respiration is a specific series of enzyme controlled chemical reactions in which oxygen is involved in the breakdown of glucose into carbon-dioxide and water. The chemical-bond energy is released in the form of ATP. Sugar + Oxygen  carbon dioxide + water + energy (ATP)

12. Aerobic Respiration Simplified Reaction: C 6 H 12 O 6 (aq) + 6O 2 (g) → 6CO 2 (g) + 6H 2 O (l) ΔH c - 2880 kJ Covalent bonds in glucose contain large amounts of chemical potential energy. The potential energy is released and utilized to create ATP.

13. Glycolysis Glycolysis is a series of enzyme controlled anaerobic reactions that result in the breakdown of glucose and the formation of ATP.

14. Glycolysis A 6-carbon sugar glucose molecule is split into two smaller 3-carbon molecules which are further broken down into pyruvic acid or pyruvate. 2 ATP molecules are created during glycolysis and electrons are released during the process.

15. Krebs Cycle The Krebs cycle is a series of enzyme- controlled reactions that take place inside the mitochondrion. Pyruvic acid formed during glycolysis is broken down further. Carbon dioxide, electrons, and 2 molecules of ATP are produced in this reaction.

16. Electron Transport System The electrons released from glycolysis and the Krebs cycle are carried to the electron- transport system (ETS) by NADH and FADH 2. The electrons are transferred through a series of oxidation-reduction reactions until they are ultimately accepted by oxygen atoms forming oxygen ions. 32 molecules of ATP are produced.

17. Aerobic Respiration Summary Glucose enters glycolysis. Broken down into pyruvic acid. Pyruvic acid enters the Krebs cycle. Pyruvic acid is further broken down and carbon-dioxide is released.

18. Aerobic Respiration Summary Electrons and hydrogen ions from glycolysis and the Krebs cycle are transferred by NADH and FADH 2 to the ETS. Electrons are transferred to oxygen to form oxygen ions. Hydrogen ions and oxygen ions combine to form water.

19. Anaerobic Cellular Respiration Anaerobic respiration does not require oxygen as the final electron acceptor. Some organisms do not have the necessary enzymes to carry out the Krebs cycle and ETS. Many prokaryotic organisms fall into this category. Yeast is a eukaryotic organism that performs anaerobic respiration.

20. Fermentation Fermentation describes anaerobic pathways that oxidize glucose to produce ATP. An organic molecule is the ultimate electron acceptor as opposed to oxygen. Fermentation often begins with glycolysis to produce pyruvic acid.

21. Alcoholic Fermentation Alcoholic fermentation is the anaerobic pathway followed by yeast cells when oxygen is not present Pyruvic acid is converted to ethanol and carbon-dioxide. 4 ATPS are generated from this process, but glycolysis costs 2 ATPs yielding a net gain of 2 ATPs.

22. Lactic Acid Fermentation In Lactic acid fermentation, the pyruvic acid from glycolysis is converted to lactic acid. The entire process yields a net gain of 2 ATP molecules per glucose molecule. The lactic acid waste products from these types of anaerobic bacteria are used to make fermented dairy products such as yogurt, sour cream, and cheese.

23. Lactic Acid Fermentation Lactic acid fermentation occurs in the human body in RBCs and muscle cells. Muscle cells will function aerobically as long as oxygen is available, but will function anaerobically once the oxygen runs out.

24. Lactic Acid Fermentation Nerve cells always require oxygen for respiration. RBCs lack a nucleus and mitochondria and therefore must always perform anaerobic, lactic acid fermentation.

25. Fat Respiration A triglyceride (neutral fat) consists of a glycerol molecule with 3 fatty acids attached to it. A molecule of fat stores several times the amount of energy as a molecule of glucose. Fat is an excellent long-term energy storage material. Other molecules such as glucose can be converted to fat for storage.

26. Protein Respiration Protein molecules must first be broken down into amino acids. The amino acids must then have their amino group (-NH2) removed (deamination). The amino group is then converted to ammonia. In the human body ammonia is converted to urea or uric acid which can then be excreted.

27. Glycolysis Glycolysis is also known as the Embden- Meyerhof Pathway. Glycolysis is a pathway for carbohydrate metabolism that begins with the substrate D- glucose. All organisms can use glucose as an energy source for glycolysis.

28. Glycolysis Glycolysis likely the first successful energy harvesting pathway that evolved on earth. The pathway evolved at a time when the Earth’s atmosphere was anaerobic; no free oxygen was available. Glycolysis is an anaerobic process that requires no oxygen.

29. Glycolysis Glycolysis evolved in very simple, single-celled organisms much like bacteria. These organisms did not have complex organelles in the cytoplasm to carry out specific cellular functions. There are ten steps in glycolysis, catalyzed by ten enzymes.

30. Glycolysis - Investment Phase The first five steps of glycolysis involve an energy investment. This is referred to as the preparatory (or investment) phase. Energy is consumed to convert glucose into two three-carbon sugar phosphates. 2 ATP are consumed.

31. Glycolysis – Pay-off Phase In the remaining steps of glycolysis, energy is harvested to produce a net gain of ATP. This phase involves a net gain of the energy rich molecules ATP and NADH. 2 triose sugars are produced in the preparatory phase; therefore, each reaction in the pay-off phase occurs twice per glucose molecule. This yields a total of 2 NADH molecules and 4 ATP molecules.

32. Glycolysis The major products of glycolysis are: Chemical energy in the form of ATP. Chemical energy in the form of NADH. Two three-=carbon pyruvate molecules.

33. Preparatory Phase – Step 1 The first step in glycolysis involves phosphorylation of glucose to form glucose 6- phosphate. The enzyme hexokinase catalyzes this reaction. This keeps glucose concentration in the cell low to facilitate continual diffusion of glucose into the cell. 1 ATP is consumed.

34. Preparatory Phase – Step 1 Glucose (Glc) ATPADP Hexokinase (HK) Glucose-6-phosphate (G6P) H+H+

35. Preparatory Phase – Step 2 Glucose 6-phosphate is then rearranged into fructose 6-phosphate. The enzyme glucose phosphate isomerase catalyzes this reaction. No ATP is consumed.

36. Preparatory Phase – Step 2 Glucose 6- phosphate (G6P) Phosphoglucose isomerase Fructose 6-phosphate (F6P)

37. Preparatory Phase – Step 3 Fructose 6-phosphate is then converted to Fructose 1,6-biphosphate. The enzyme phosphofructokinase catalyzes this reaction. 1 ATP is consumed. This reaction destabilizes the molecule. Unlike the previous reactions, this reaction is essentially irreversible. A different chemical pathway must be used for gluconeogenesis.

38. Preparatory Phase – Step 3 Fructose 6-phosphate (F6P) Phosphofructokinase (a transferase) Fructose 1,6- bisphosphate (F1,6BP) ATPADP H+H+

39. Preparatory Phase – Step 4 The destabilization of the molecule from the previous reaction allows for splitting of the hexose ring. Fructose 1,6-bisphosphate is split into two triose sugars. Glyceraldehyde 3-phosphate Dihydroxyacetone phosphate The enzyme fructose bisphosphate aldolase catalyzes this reaction.

40. Preparatory Phase – Step 4 + Fructose 1,6- bisphosphate (F1,6BP) Fructose bisphosphate aldolase (ALDO) Glyceraldehyde 3-phosphate (GADP) Dihydroxyacetone phosphate (DHAP)

41. Preparatory Phase – Step 5 Dihydroxyacetone phosphate (DHAP) can be interconverted to glyceraldehyde 3-phosphate (GADP). The enzyme triosephosphate isomerase catalyzes this reaction. GADP proceeds into the pay-off phase of glycolysis.

42. Preparatory Phase – Step 5 Dihydroxyacetone phosphate (DHAP) Triesophosphate isomerase (TPI) Glyceraldehyde 3- phosphate (GADP)

43. Pay-Off Phase - Step 1 GADP is dehydrogenated and inorganic phosphate is added to them forming 1,3- bisphosphoglycerate. The enzyme glyceraldehyde phosphate dehydrogenase catalyzes this reaction. Hydrogen is used to reduce two molecules of NAD + to give NADH and H +.

44. Pay-Off Phase - Step 1 Glyceraldehyde 3- phosphate (GADP) Glyceraldehyde 3- phosphate dehydrogenase (GADPH) 1,3- bisphosphoglycerate (1,3-BPG) NAD + NADH PiPi H+H+

45. Pay-Off Phase - Step 2 In this step a phosphate group is transferred from 1,3 bisphosphoglycerate to ADP to form ATP and 3-phosphoglycerate. The enzyme phosphoglycerate kinase (a transferase) catalyzes this reaction. 1 ATP is generated in this step.

46. Pay-Off Phase - Step 2 1,3- bisphosphoglycerate (1,3-BPG) Phosphoglycerate kinase (PGK) (a transferase) 3-phosphoglycerate (3-P-G) ADPATP Phosphoglycerate kinase

47. Pay-Off Phase – Step 3 3-phosphoglycerate is converted to 2- phosphoglycerate. The enzyme phosphoglycerate mutase catalyzes this reaction.

48. Pay-Off Phase – Step 3 3-phosphoglycerate (3PG) Phosphoglycerate mutase (PGM) 2-phosphoglycerate (2PG)

49. Pay-Off Phase - Step 4 2-phosphoglycerate is converted to phosphoenolpyruvate. The enzyme enolase catalyzes this reaction. This is a dehydration reaction. Water is released.

50. Pay-Off Phase - Step 4 2-phosphoglycerate (2PG) Enolase (ENO) Phosphoenolpyruvate (PEP) H2OH2O

51. Pay-Off Phase - Step 5 Phosphoenolpyruvate is converted to pyruvate. ADP is phosphorylated to ATP. The enzyme pyruvate kinase (a transferase) catalyzes this reaction. 1 ATP is generated in this reaction.

52. Pay-Off Phase - Step 5 Phosphoenolpyruvate (PEP) Pyruvate kinase (PK) (a transferase) Pyruvate (Pyr) ADPATP H+H+

53. Pay-Off Phase The payoff phase generates 2 ATP for each triose sugar from the preparatory phase. 2 triose sugars are generated in the preparatory phase from each molecule of glucose that enters into glycolysis. Consequently, 4 ATP are generated during the payoff phase for each molecule of glucose.

54. Pay-Off Phase 2 ATP are consumed for each molecule of glucose during the preparatory phase. A net gain of 2 ATP per molecule of glucose is obtained from glycolysis.