1. Cellular Respiration: Day 04
Process whereby cells breakdown glucose and other food molecules to release energy.

2. Updates
We will test on Cellular Respiration before moving onto Photosynthesis
Test will be next week sometime
When? It depends on if we miss school for the elections or not – check our WIKI!!
Lab – Lets talk about that first!

3. Lets Review the Cellular Respiration Cycle
Lets begin with a Respiration Tutorial
Take a look at the big picture!

4. When you exercise:
Muscles need energy in order to perform work.
Enzymes in muscle cells help the cell convert glucose and oxygen into ATP (usable energy).

5. Terms we have discussed:
Aerobic Metabolism
Anaerobic Metabolism
Autotrophs
Heterotrophs
Producers
Consumers

6. Chemical Cycling Between Photosynthesis and Cellular Respiration
The ingredients for photosynthesis are carbon dioxide and water.
CO2 is obtained from the air by pores on a plant’s leaves.
H2O is absorbed from the damp soil by the roots.
Veins transport the water from roots to leaves.
Chloroplasts rearrange the atoms of these ingredients to produce sugars (glucose) and other organic molecules (key products = glucose and oxygen).
Oxygen gas is a by-product of photosynthesis

7. Photosynthesis
Respiration

8. CELLULAR RESPIRATION: AEROBIC HARVEST OF FOOD ENERGY
The main way that chemical energy is harvested from food and converted to ATP
This is an aerobic process—it requires oxygen

9. The Overall Equation for Cellular Respiration
A common fuel molecule for cellular respiration is glucose.
This is the overall equation for what happens to glucose during cellular respiration.
Glucose
Oxygen
Carbon
dioxide
Water
Energy
Cellular respiration can produce up to 38 ATP molecules for each glucose molecule consumed.

10. The Metabolic Pathway of Cellular Respiration
Cellular respiration is an example of a metabolic pathway (a series of chemical reaction in cells).
All of the reactions involved in cellular respiration can be grouped into three main stages:
Glycolysis
The Krebs cycle
Electron transport

11. Why does electron transfer to oxygen release energy?
When electrons move from glucose to oxygen, it is as though they were falling
This “fall” of electrons releases energy during cellular respiration
Release
of heat
energy
Figure 6.5

12. NADH and Electron Transport Chains
The path that electrons take on their way down from glucose to oxygen involves many stops
1/2
(from food via NADH)
Energy for
synthesis of
2 H
2 e
Electron transport chain
2 e
1/2
2 H
Figure 6.6

13. A Road Map for Cellular Respiration
Cytosol
Mitochondrion
High-energy
electrons
carried
by NADH
High-energy
electrons carried
mainly by
NADH
Glycolysis 2
Pyruvic
acid
Krebs
Cycle
Electron
Transport
Glucose

14. I. Glycolysis (click) Process whereby one glucose molecule is broken in half producing two pyruvate molecules.
Takes place in cell’s cytoplasm.
Does not require O2 to take place.
Occurs very rapidly, however, low energy yield (Net 2 ATP and 2 NADH produced)

15. Cell with Mitochondria (red spots)

16. Mitochondria
Site of Krebs cycle and Electron Transport Chain

17. II. Krebs Cyle (click) Process whereby pyruvate is broken down into CO2 in a series of energy releasing reactions.
Only occurs if O2 is present (aerobic respiration).
Takes place within the mitochondria of the cell.
Each pyruvate that goes through the cycle produces 1 ATP, 4 NADH, 1 FADH2 and 3 CO2 (2 X that amount for each glucose molecule).

18. III. Electron Transport Chain (click) Uses the high energy electrons from NADH and FADH2 to convert ADP into ATP.
Occurs in proteins that are embedded within the inner membrane of the mitochondria.
As high energy electrons from NADH and FADH2 are passed from protein to protein in the “chain”, H+ ions are pumped across the membrane.
H+ ions flow back through ATP synthase which converts ADP into ATP.
Final electron acceptor in the “chain” is O2 forming a H2O molecule.
10 NADH and 2 FADH2 make a total of 34 ATPs.

19. Adding Up the ATP from Cellular Respiration
Cytosol
Mitochondrion
Glycolysis 2
Acetyl-
CoA 2
Pyruvic
acid
Krebs
Cycle
Electron
Transport
Glucose
Maximum
per
glucose: by
direct
synthesis by
ATP
synthase
by direct
synthesis
Figure 6.14

20. The Versatility of Cellular Respiration
Cellular respiration can “burn” other kinds of molecules besides glucose.
Diverse types of carbohydrates
Fats
Proteins

21. FERMENTATION: ANAEROBIC HARVEST OF FOOD ENERGY
Some of your cells can actually work for short periods without oxygen.
For example, muscle cells can produce ATP under anaerobic conditions.
Fermentation
The anaerobic harvest of food energy

22. Without Oxygen!!! We cannot enter the Krebs Cycle
Must use Anaerobic Respiration
Alcohol Fermentation
Lactic Acid Fermentation

23. In order for Glycolysis to continue NAD+ must be present.
Without O2 (anaerobic respiration) the NADH can not move onto the Krebs cycle.
Think of NADH as “full moving trucks” which must be unloaded for the company to survive.
Like our lab!!

24. 2 ways to “unload” the NADH in anaerobic environments
Alcohol Fermentation NADH passes electron back to pyruvic acid creating alcohol molecules. Occurs in yeast and other microorganisms
Lactic Acid Fermentation NADH passes electron back to pyruvic acid creating lactic acid molecules. Occurs with our muscle cells and other prokaryotes (helps make yogurt, kimchi and cheese!)

25. Fermentation in Human Muscle Cells
Human muscle cells can make ATP with and without oxygen
They have enough ATP to support activities such as quick sprinting for about 5 seconds
A secondary supply of energy (creatine phosphate) can keep muscle cells going for another 10 seconds
To keep running, your muscles must generate ATP by the anaerobic process of fermentation

26. Glycolysis is the metabolic pathway that provides ATP during fermentation.
Pyruvic acid is reduced by NADH, producing NAD+, which keeps glycolysis going
In human muscle cells, lactic acid is a by-product

27. (a) Lactic acid fermentation
2 ADP+ 2
Glycolysis
2 NAD
2 NAD
Glucose
2 Pyruvic
acid
+ 2 H
2 Lactic
acid
(a) Lactic acid fermentation

28. Fermentation in Microorganisms
Various types of microorganisms perform fermentation.
Yeast cells carry out a slightly different type of fermentation pathway
This pathway produces CO2 and ethyl alcohol

29. (b) Alcoholic fermentation
2 ADP+ 2
2 CO2 released
2 ATP
Glycolysis
2 NAD
2 NAD
Glucose
2 Ethyl
alcohol
2 Pyruvic
acid
+ 2 H
(b) Alcoholic fermentation
Figure 6.15b

30. The food industry uses yeast to produce various food products
Figure 6.16

31. Respiration tutorial Both high and low oxygen settings
Copy and paste the questions into your onenote and answer there.
Read the blurb at the beginning of each section before pressing play.

32. Images Cited