1. Where do animal cells get their energy?
Cellular Respiration
Where do animal cells get their energy?

2. Remember
Energy used by all Cells.
Organic molecule containing high-energy Phosphate bonds

3. How Do We Get Energy From ATP?
By breaking the high- energy bonds between the last two phosphates in ATP

4. Cellular Respiration
The process of cell catabolism in which cells turn food into usable energy in the form of ATP. In this process glucose is broken down in the presence of molecular oxygen into six molecules of carbon dioxide, and much of the energy released is preserved by turning ADP and free phosphate into ATP. Cellular respiration occurs as a series of chemical reactions catalyzed by enzymes, the first of which is glycolysis, a series of anaerobic reactions in which glucose (a 6-carbon molecule) is split into two molecules of lactate (a 3-carbon molecule), producing a net gain of two ATP molecules. In a series of aerobic reactions, lactate is converted to pyruvate, which enters the mitochondrion and combines with oxygen to form an acetyl group, releasing carbon dioxide. The acetyl group (CH 3 CO) is then combined with coenzyme A as acetyl coenzyme A, and enters the Krebs cycle. During this series of reactions, each acetyl group is oxidized to form two molecules of carbon dioxide, and the energy released is transferred to four electron carrier molecules. The electron carrier molecules then release their energy in a process that results in the pumping of protons (hydrogen ions) out across the inner membrane of the mitochondrion. The potential energy of the protons generated by one acetyl group is later released when they recross the membrane and are used to form three molecules of ATP from ADP and phosphate in the process of oxidative phosphorylation. The pyruvate from one molecule of glucose drives two turns of the Krebs cycle. Thus, during cellular respiration one molecule of glucose, as well as oxygen, ADP, and free phosphate are catabolized to yield six molecules of carbon dioxide and an increase in usable energy in the form of eight molecules of ATP.

5. Glycolysis: the breakdown of glucose by enzymes, releasing energy and pyruvic acid.
Pyruvic Acid: organic acid that occurs as an intermediate in many metabolic processes, especially glycolysis
Anaerobic Respiration: A form of cellular respiration that occurs when oxygen is absent or scarce. The process of generating energy by the oxidation of nutrients and using an external electron acceptor other than oxygen.
Fermentation: enzymatically controlled anaerobic breakdown of an energy-rich compound
Aerobic Respiration: A form of cellular respiration that requires oxygen in order to generate energy. The process of generating energy by the full oxidation of nutrients through Krebs cycle where oxygen is the final electron acceptor.

6. Where Does Cellular Respiration Take Place?
It actually takes place in two parts of the cell:
* Glycolysis occurs in the Cytoplasm
* Krebs Cycle & ETC Take place in the Mitochondria

7. Review of Mitochondria Structure
Smooth outer Membrane
Folded inner membrane
Folds called Cristae
Space inside cristae called the Matrix

8. Explain: Where do our cells get energy?
6-C sugars are the MAJOR source of energy for cell
What type of macromolecule are 6-C sugars?
Carbohydrates
Cells break down glucose a 6-C sugar to make ATP “energy”

9. 6 Carbon Sugars: They even count the sugars for you…

10. Cellular Respiration (3-stages)
Glycolysis
Krebs Cycle (Citric Acid Cycle)
Electron Transport Chain (ETC)
Glucose
Glycolysis
Krebs Cycle
Electron Transport
Fermentation (without oxygen)
Alcohol or lactic acid
Glucose
Krebs cycle
Electron transport
Glycolysis
Fermentation (without oxygen)
Alcohol or lactic acid

11. Overall Chemical Process
C6H12O6 + 6O2  6CO2 + 6H2O + usable energy
Sugar + Oxygen  Carbon dioxide + Water + ATP

12. Flowchart of Cellular Respiration 
Carbon
Dioxide
(CO2) +
Water
(H2O)
ATP
Glucose (C6H1206) +
Oxygen (02)
Glycolysis
Krebs Cycle
Electron Transport Chain

13. Glycolysis Where Cytoplasm NO O2 required
Energy Yield net gain of 2 ATP at the expense of 2 ATP
6-C glucose  TWO 3-C pyruvates
Free e- and H+ combine with organic ion carriers called NAD+  NADH + H+
(nicotinamide dinucleotide)

14. To the electron transport chain
Glycolysis:
Glucose
2 Pyruvic acid
To the electron transport chain

15. To the electron transport chain
 Glycolysis step 1
Glucose
2 Pyruvic acid
To the electron transport chain

16. To the electron transport chain
Glycolysis Step 2
Glucose
2 Pyruvic acid
To the electron transport chain

17. C.R. Reactions Glycolysis
Series of reactions which break the 6- carbon glucose molecule down into two 3- carbon molecules called pyruvate
Process is an ancient one-all organisms from simple bacteria to humans perform it the same way
Yields 2 ATP molecules for every one glucose molecule broken down
Yields 2 NADH per glucose molecule

18. Summary In Out Glucose (6-C) 2 pyruvate; 2(3- C) 2 ATP 2NADH
a net of 2 ATP

19. Questions Where does glycolysis take place?
____________________________________________
It needs _______ ATP to work.
It provides _______ ATP a net gain of _______.
Breaks glucose into TWO ___________.
It is an Aerobic or Anaerobic process?

20. After Glycolysis
After glycolysis, about 90 percent of the energy in glucose is still unused.
Oxygen is required to extract the rest of the energy (aerobic process).

21. Still Need a review? Click on the picture.

24. Aerobic Cellular Respiration
Oxygen required=aerobic
2 more sets of reactions which occur in a specialized structure within the cell called the mitochondria
1. Kreb’s Cycle
2. Electron Transport Chain

25. Krebs Cycle aka Citric Acid Cycle

26. A Little Krebs Cycle History
Discovered by Hans Krebs in 1937
He received the Nobel Prize in physiology or medicine in 1953 for his discovery
Forced to leave Germany prior to WWII because he was Jewish

27.  The Krebs Cycle
Citric Acid Production
Mitochondrion

28. Kreb’s Cycle Completes the breakdown of glucose
Takes the pyruvate (3-carbons) and breaks it down, the carbon and oxygen atoms end up in CO2 and H2O
Hydrogens and electrons are stripped and loaded onto NAD+ and FAD to produce NADH and FADH2
Production of only 2 more ATP but loads up the coenzymes with H+ and electrons which move to the 3rd stage

29. Krebs Cycle Requires Oxygen (Aerobic)
Cyclical series of oxidation reactions that give off CO2 and produce one ATP per cycle
Turns twice per glucose molecule
Produces two ATP
Takes place in matrix of mitochondria

30. Review of Mitochondria Structure
Smooth outer Membrane
Folded inner membrane
Folds called Cristae
Space inside cristae called the Matrix

31. Krebs Cycle
Each turn of the Krebs Cycle also produces 3 NADH, 1 FADH2, and 2 CO2
Therefore, For each Glucose molecule, the Krebs Cycle produces 6 NADH, 2 FADH2, 4 CO2, and 2 ATP

32. First Step: Krebs Cycle/Citric Acid Cycle Breakdown of Pyruvic Acid
Where mitochondria matrix
Pyruvate (3-C)  Acetic acid (2-C)
3rd C forms CO2
Acetic acid combines with Coenzyme A to form ACETYL-CoA

33. What is releasing Energy with O2?
Summary In
Pyruvate
NAD
CoA
Out
CO2 (as waste)
NADH
Acetyl-CoA
What is releasing Energy with O2?
Aerobic respiration
Where In the cells mitochondria

34. Second Step: Krebs Cycle or Citric Acid Cycle
Where Mitochondrial matrix
Energy Yield 2 ATP and more e-
Acetyl-CoA (2-C) combines with 4-C to form 6-C CITRIC ACID
Citric Acid (6-C) changed to 5-C then to a 4-C
Gives off a CO2 molecule
NAD+ and FAD pick up the released e-
FAD becomes FADH2
NAD+ becomes NADH + H+
Cycle ALWAYS reforming a 4-C molecule

35. Krebs Cycle

36. Still Need a review? Click on the picture.
Citric Acid Production
Mitochondrion

39. Electron Transport Chain
Aka ETC

40. Electron Transport Chain
Electron carriers loaded with electrons and protons from the Kreb’s cycle move to this chain-like a series of steps (staircase).
As electrons drop down stairs, energy released to form a total of 34 ATP
Oxygen waits at bottom of staircase, picks up electrons and protons and in doing so becomes water

41. ETC Where inner membrane of mitochondria
Energy Yield Total of 34 ATP
O2 combines with 2 H+ to form H2O
Exhale (waste product) - CO2, H2O comes from cellular respiration

42. Electron Transport Chain
Mitochondrion
Hydrogen Ion Movement
Channel
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production

46. Other ETC videos

47. So where did all the ATP come from again…

48. Total ENERGY Yield
Glycolysis 2 ATP
Krebs Cycle 2 ATP
ETC  34 ATP
Total 38 ATP

50. What happens if no O2? Cellular respiration process STOPS…
but life needs to go on …

51. Anaerobic respiration

52. Fermentation Anaerobic respiration (requires no oxygen)
Only 2 ATP are made in anaerobic respiration so it is not as good as aerobic respiration (34 ATP)
Both begin with glycolysis (remember this process was anaerobic.)
No Krebs (citric acid) cycle or electron transport chain

53. Two Types of Fermentation
Alcoholic Fermentation
Used by yeasts and a few other micro-organisms with ethyl alcohol and carbon dioxide as waste products.
Causes bread to rise.

54. Lactic Acid Fermentation
Lactic acid is produced from pyruvic acid.
Produced in muscles during rapid exercise when enough oxygen is not present.
Unicellular organisms also produce lactic acid as a waste product.
Prokaryotes are used in the production of cheese, yogurt, buttermilk, sour cream, pickles, sauerkraut, and kimchi.

56. Anaerobic Respiration
Only 2 ATP are made in anaerobic respiration so it is not as good as aerobic respiration (38 ATP).
Glycolysis
Glucose Pyruvate + 2 ATP
Followed by one of these 2 processes.
Alcoholic Fermentation
Pyruvate ethyl alcohol + CO2
Lactic Acid Fermentation
Pyruvate Lactic Acid
Carried out by yeast & some
bacteria.
-Used in brewing beer &
making cakes.
Carried out by your muscle
cells when you are exercising
hard (need ATP)
-Causes muscle cramps &
soreness.

57. Aerobic vs. Anaerobic ATP Aerobic DOES requires oxygen It…
Anaerobic DOES NOT require oxygen.
It is …
Simple
fast
produces smaller amounts of energy
Aerobic DOES requires oxygen
It…
Yields large amounts of energy
But is not simple, fast or efficient
What is the energy molecule that is created?
ATP

58. Releasing Energy with out Oxygen
Anaerobic Respiration
NO Additional ATP is Formed
No Oxygen leads to Fermentation
Two Types
Lactic Acid Fermentation
Alcoholic Fermentation

61. What are the 2 chemical equations?
Alcoholic fermentation
pyruvic acid + NADH → alcohol + CO₂ + NAD⁺
Lactic acid fermentation
pyruvic acid + NADH → lactic acid + NAD⁺
What are the differences?

62. Review Time…

64. Energizes 2 electron carriers.(NAD+ NADH)
Step 1 Glycolysis occurs in the cytoplasm.
Glucose is broken in half to form two pyruvate molecules.
A small amount of energy (ATP) is also produced.
ATP
Glycolysis
Glucose
Pyruvate
Pyruvate
ATP
Energizes 2 electron carriers.(NAD NADH)

65. Step 2: Kreb’s Cycle (Citric Acid Cycle) occurs inside the mitochondria.
ATP
ATP
Kreb’s Cycle
Citric Acid
Pyruvic Acid e- e-
NADH e-
CO2

66. Kreb’s Cycle/ Citric Acid Cycle cont…
3 Products from Kreb’s Cycle…
1. Carbon Dioxide released (like in your
breath).
2. ATP provides energy for cellular
activities.
3. High-energy electron (carried by
electron carriers) that can be used to
generate large amounts of ATP.

67. Step 3: Electron transport chain occurs in the mitochondria.
Electrons move down the electron transport chain.
Electrons are caught by oxygen to make water.
34 ATP are also made.
NADH e- e-
34ATP e-
Oxygen we breathe
We use for energy
Water

68. Electron Transport Chain
Uses the high-energy electrons from the Kreb’s cycle to convert ADP to ATP.
Electrons are passed from one carrier protein to the next and finally combine with hydrogen ions & oxygen to form water.