1. …Using glucose to make energy (ATP)
Cellular Respiration
…Using glucose to make energy (ATP)

2. Questions for this Lesson
If plants need ATP (energy) to form glucose, how can glucose be a source of energy for plants and animals?
How does our body use glucose to make energy?
Why do your muscles get really sore when you exercise intensely, but not when you pace yourself?
How do you get wine from grapes?

3. Where Do Plants Get Energy?
Plants get energy from the sun and store it in the bonds of ___________.
glucose

4. Harvesting Chemical Energy:
Cellular respiration is a biochemical pathway which allows cells to make ATP by breaking down organic molecules such as glucose
Autotrophs like plants, and heterotrophs like humans both go through cellular respiration
Autotrophs produce glucose through the process of photosynthesis
Heterotrophs obtain glucose through eating

6. Glucose Turns into Energy
How do we get energy?
by eating food.
What types of food provide the most energy?
Carbs (sugars or glucose) have the most energy
e.g. candy bars, wheat, potatoes, rice, pasta
What does your body do to the food you eat?
- Our body digests our food (breaks apart bonds), releasing energy

7. Breaking Bonds -review
Breaking bonds releases energy!
Energy is “stored” in the glucose bonds; breaking them releases the energy
What form of energy do our cell (and our body) use?
the molecule ATP
So.. our body breaks down
glucose and uses it to make ATP (ENERGY!)
Which organelle is
responsible for producing
energy for our cells?
The MITOCHONDRIA

8. What is ATP? -review
ATP (adenosine triphosphate) is a nucleic acid that can transfer energy within the cell.
Ex: a small amount of energy from a glucose molecule can be used directly…
The extra energy is transferred to ATP.
The energy in ATP is stored in the bonds between the phosphates (ATP has 3 phosphates).

9. Overview of Cellular Respiration:
Divided into 2 stages:
Glycolysis
Glucose is converted into 2 molecules of pyruvic acid (a 3-carbon compound); this produces a small amount of ATP and NADH (an electron carrier); it is an anaerobic process
Aerobic respiration
Pyruvic acid is broken down into NADH is used to produce a large amount of ATP
Overall equation for cellular respiration:
C6H12O6 + 6O2 6CO2 + 6H2O + ATP

10. Steps of Cellular Respiration
GLYCOLYSIS (glyco = glucose, lysis = break)
- Occurs in the cytoplasm of the cell
2 Phosphate groups are added to glucose – uses 2 ATPs
6-C compound splits into two 3-C compounds called G3P
G3P oxidizes and obtains another phosphate group and is accompanied by the reduction of 2 molecules of NAD+ (nicotinamide adenine dinucleotide) to NADH
The 4 phosphate groups are removed from the G3P
This results in 2 molecules of pyruvic acid
The 4 removed phosphate groups combine with 4 molecules of ADP to produce 4 ATP
Since 2 were used in step 1, the net gain of ATP is 2

12. Steps of Cellular Respiration (con’t) …Why Glycolysis?
Why would we need to break down glucose in the cytoplasm first before we use it in the mitochondria? (think transport)
Glucose molecules are too large to move into the mitochondria, so glycolysis makes them smaller to get through the mitochondria’s membranes
video

14. Steps of Cellular Respiration (con’t)
After glycolysis, there are two possible paths:
Aerobic respiration – requires oxygen
Anaerobic respiration – does not require oxygen; happens if oxygen is lacking
Oxygen? NO
Anaerobic Respiration
Aerobic Respiration
YES

15. Anaerobic Cellular Respiration
Fermentation - anaerobic process (does not require oxygen)
some cells can convert pyruvic acid from glycolysis into other compounds and regenerate NAD+ (which keeps glycolysis going)
Two types of fermentation:
Alcohol fermentation
Lactic acid fermentation
Both take place in the cytoplasm.

17. Lactic Acid Fermentation:
Pyruvic acid is converted into lactic acid and
NAD + is regenerated
used in the manufacturing of many dairy products like yogurt and cheese
also occurs in your muscle cells during strenuous exercise
-as oxygen is used up, cells will switch over to using fermentation to regenerate NAD+, this causes a build-up of lactic acid in your muscle cells causing muscle fatigue and burning
Breathe heavier and faster to bring more oxygen into your cells and remove the lactic acid

19. Alcoholic Fermentation
Some plant cells and yeasts use alcoholic fermentation to convert pyruvic acid into ethyl alcohol and to regenerate NAD+
A molecule of CO2 is removed and released as a gas; the resulting 2-C compound is then used to produce ethanol (ethyl alcohol)
Used in the wine and beer making industries
Used in baking  yeast will ferment the glucose present in the dough, causing CO2 to be released, which is what causes dough to rise, and there to be air bubbles in bread

20. Bozeman Video

21. What’s the big deal about aerobic vs. anaerobic respiration?
You get way more ATP from aerobic cellular respiration than you do from anaerobic cellular respiration (fermentation).
Fermentation is mostly used to provide organisms with short-term bursts of energy when oxygen is not available.

22. Aerobic Cellular Respiration
An aerobic process (requires oxygen).
Reaction releases energy from the chemical bonds of carbohydrates.
Takes place in the mitochondria.
Equation:
6O C6H12O H CO ATP
Oxygen + Glucose Water + Carbon Dioxide + Energy

23. HOLD IT! Notice Anything Similar?
Equation for photosynthesis:
Energy H2O CO C6H12O O2
Equation for aerobic cellular respiration:
6O C6H12O H CO ATP

24. Organisms that Carry Out Aerobic Cellular Respiration

25. Organisms that Carry Out Aerobic Cellular Respiration
Plants
Animals
Fungi
Protists
Some bacteria
…almost everything alive!

26. Aerobic Cellular Respiration
Step 1 = glycolysis 2 ATP molecules are produced in cytoplasm and enter mitochondria.
For aerobic respiration, in mitochondria:
Step 2 = Krebs Cycle (Citric Acid Cycle) – in matrix
Step 3 = Electron Transport Chain – in inner membrane
ATP is generated in each step, but most of the ATP is made in the
Electron Transport Chain

28. Pre-Krebs Cycle
Pyruvic acid (made in glycolysis) diffuses across the double membrane of the mitochondria into its matrix
Pyruvic acid will react with coenzyme A to form acetyl coenzyme A (acetyl CoA)
Pyruvic acid is a 3-C compound and Acetyl CoA is a 2- C compound. The other C atom is used in the formation of CO2 which we exhale.
Each pyruvic acid molecule (there are 2) produces
1 NADH (2 total) – will enter the ETC
1 CO2 (2 total) – diffuses out of cell as waste
1 Acetyl CoA 2(total) – used in the Krebs Cycle

29. Krebs Cycle (matrix) AKA: The Citric Acid Cycle-
Acetyl CoA combines with a compound to form citric acid
Each Acetyl CoA (2total) will produce
2-CO2 (4 total) – diffuses out of cell as waste
1-ATP (2 total) – used to do work
3-NADH (6 total) – will enter the ETC
1-FADH2 (2 total) – will enter the ETC

31. Electron Transport Chain
Electron Transport Chain – Moves electrons along a series of molecules so H+ ions can be pumped from the mitochondrial matrix to the space between the 2 membranes.
Located on the inner mitochondrial membrane on the folds called christae
ATP is produced through chemiosmosis
Each NADH can produce 3 ATP
Each FADH2 can produce 2 ATP

33. During Glycolysis, Pre Krebs, Krebs, and the ETC a total of 38 ATP will be made.
Since Glycolysis occurs in the cytosol the NADH made needs to be actively transported into the mitochondria. That requires 2 ATP to be used so there is a total net gain of 36 ATP from one glucose molecule.

34. Summary of Aerobic Respiration
C6H12O O → CO H2O ATP
Glucose + Oxygen → Carbon dioxide + Water + ATP
(Krebs Cycle)

35. Role of OXYGEN O2 is the final electron acceptor in the ETC.
It bonds w/H+ that are being pumped into the mitochondrial matrix to form water.
Without O2, cells will undergo fermentation and ATP will not be made.

36. Other Catabolic Pathways
What about lipids, proteins, and nucleic acids?
Starch: broken down into glucose, which enters glycolysis
Fats: broken down into fatty acids and glycerol; fatty acids are cut into 2-carbon compounds, converted to Acetyl-CoA, and enter the Krebs Cycle
Proteins: broken down into amino acids, which can be converted into Acetyl-CoA or other compounds that enter the Krebs cycle at various points
The amino group is removed & excreted as urea.

37. Nucleic Acids
Proteins
Carbohydrates
Lipids
Nucleotides
Amino Acids
Sugars
Fatty Acids/
Glycerol
Pyruvate
Acetyl-CoA
Krebs
Cycle
Urea
H2O
CO2