1. Cellular Respiration Mrs. Schenfield’s Life Science

2. Cellular Respiration Overview
Transformation of chemical energy in food into chemical energy cells can use: ATP
These reactions proceed the same way in plants and animals. Process is called cellular respiration
Overall Reaction:
C6H12O6 + 6O2 → 6CO2 + 6H2O

3. Anaerobes
Anaerobes are organisms that use the Anaerobic Respiration pathway
Most anaerobes are bacteria (not all).
Anaerobes do NOT require oxygen.

4. Aerobes
Aerobes are organisms that use the Aerobic Respiration pathway.
Aerobes require oxygen.

5. Cellular Respiration Overview
Breakdown of glucose begins in the cytoplasm: the liquid part called cytosol
Sugar is the most common energy source (some cells use fats and proteins)
Requires many enzymes
The enzymes “disassembly line” takes the sugar apart, periodically releasing small amounts of energy that fuel the cell

6. Types of Cellular Respiration
At this point life diverges into two forms and two pathways
Anaerobic cellular respiration (fermentation)
Aerobic cellular respiration

7. Cellular Respiration Reactions
Glycolysis
Series of reactions which break the 6-carbon glucose molecule down into two 3-carbon molecules called pyruvate
-all organisms from simple bacteria to humans perform it the same way
Yields 2 ATP molecules for every one glucose molecule broken down

8. Glycolysis glyco means “glucose/sugar”, and
lysis means “to split”. Therefore,
glycolysis means “to split glucose”
This process was likely used to supply energy for the ancient forms of bacteria.

10. Anaerobic Cellular Respiration
Some organisms thrive in environments with little or no oxygen
Marshes, bogs, gut of animals, sewage treatment ponds
No oxygen used= ‘an’aerobic
Results in no more ATP, final steps in these pathways serve ONLY to regenerate NAD+ so it can return to pick up more electrons and hydrogens in glycolysis.
End products such as ethanol and CO2 (single cell fungi (yeast) in beer/bread) or lactic acid (muscle cells)

11. Anaerobic Cellular Respiration
Alcoholic Fermentation-some bacteria and fungi use this as their only source of energy.
Yeast in bread dough uses this and produces carbon dioxide that gets trapped in the dough and causes bread to rise.
Yeast is a leavening agent and is mentioned in the Bible.
(enzymes)
Sugar carbon dioxide + 2 ATP

12. Alcoholic Fermentation
Uses only Glycolysis.
Does NOT require O2
Produces ATP when O2 is not available.

13. Alcoholic Fermentation C6H12O6 2 C2H5OH + 2 CO2
(Ethyl Alcohol or Ethanol)
As a result of Alcoholic Fermentation,
Glucose is converted into 2 molecules of Ethyl Alcohol and 2 Molecules of Carbon Dioxide.

14. Anaerobic Cellular Respiration
Lactic Acid Fermentation-produced and released by bacteria in yogurt, buttermilk, and sauerkraut.
If, when you exercise, you are not able to supply enough oxygen to muscle cells they will switch to anaerobic respiration which produces lactic acid.
The build up of lactic acid causes soreness in muscles.
Not as efficient as aerobic cellular respiration

15. Lactic Acid Fermentation
Uses only Glycolysis.
Does NOT require O2
Produces ATP when O2 is not available.

17. Aerobic Cellular Respiration
Oxygen required=aerobic
Mitochondria perform the “recharging” of ATP molecules by transferring energy from the sugar molecules to ATP.
(enzymes)
Sugar + oxygen carbon dioxide + water + 36 ATP
The cells of many organisms and your body perform this type of cellular respiration.

19. In order for Aerobic Respiration to continue the Pyruvic acid is first converted to Acetic Acid by losing a carbon atom and 2 oxygens as CO2.
The Acetic acid then must enter the matrix region of the mitochondria. The CO2 produced is the CO2 animals exhale when they breathe.

20. Phase Two: The Krebs Cycle (AKA the Citric Acid Cycle)
Once the Acetic Acid enters the Matrix it combines with Coenzyme A to form a new molecule called Acetyl-CoA. The Acetyl-CoA then enters the Krebs Cycle.
CoA breaks off to gather more acetic acid. The Acetic acid is broken down.
Sir Hans Adolf Krebs
Produces most of the cell's energy in the form of NADH and FADH2… not ATP
Does NOT require O2
+ 3H
3 NADH

21. Energy Tally 36 ATP for aerobic vs. 2 ATP for anaerobic
Glycolysis ATP
Kreb’s (citric acid cycle) ATP
Electron Transport 32 ATP
36 ATP
Anaerobic organisms can’t be too energetic but are important for global recycling of carbon