1. Cellular Respiration
Chapter 7
Miss Colabelli
Biology CPA

2. Cellular Respiration
Complex process that our cells make ATP by breaking down organic compounds
Organisms that use cellular respiration are known as heterotrophs

3. Cellular Respiration
Cellular Respiration is the process that releases energy by breaking down food molecules in the presence of oxygen
C6H12O6 + 6O2 6CO2 + 6H2O + ATP
Same equation for photosynthesis JUST BACKWARDS!

5. Glycolysis
Process where one molecule of glucose is broken in half, producing two 3-carbon molecules of pyruvic acid
Creates a small amount of ATP and NADH
Process is anaerobic
Does not require oxygen

6. Aerobic Respiration If oxygen is present in cell environment
Pyruvic acid is broken down to make a large amount of ATP
If no oxygen is available for the pyruvic acid
Fermentation

7. Fermentation Releases energy from pyruvic acid without oxygen
Two types
Lactic Acid
Alcoholic

8. Lactic Acid Fermentation
Lactic Acid is produced by muscles during rapid exercise when the body cannot supply enough oxygen

9. Alcoholic Fermentation
Alcoholic fermentation is done by yeasts and some microorganisms
Produces an alcohol & Carbon dioxide

10. Glycolysis Glucose  2 pyruvic acid molecules Step 1:
Glucose molecule uses two ATP molecules to make a 6-carbon molecule with two phosphates

11. Glycolysis
Step 2:
Glucose molecule breaks in half to make two G3P molecules

12. Glycolysis
Step 3:
Each G3P molecule gets a phosphate added and 2 NAD+ are reduced and gain an electron to become NADH

13. Glycolysis
Step 4:
Each 3-Carbon molecule loses their phosphates to make 4 molecules of ATP, 2 molecules of water, and 2 molecules of pyruvic acid

14. Fermentation Anaerobic process after glycolysis
Pyruvic acid is used to become either lactic acid or ethyl alcohol
This process is important because it regenerates NAD+ molecules for glycolysis to continue to work

15. Lactic Acid Fermentation
Pyruvic acid  lactic acid
NADH  NAD+
Important for making dairy products
Produces certain cheeses and yogurts
Occurs naturally in your muscles when you work out
Muscle soreness

16. Lactic Acid Fermentation
Muscles use up all available oxygen
Switch to anaerobic respiration
Increases acid levels in muscles causing the fatigue
Eventually gets processed in liver back to pyruvic acid

17. Lactic Acid Fermentation

18. Alcoholic Fermentation
Pyruvic acid  ethyl alcohol
NADH  NAD+
Ethyl alcohol is a 2-carbon molecule
Pyruvic acid loses a carbon by releasing CO2

19. Alcoholic Fermentation
Yeast needs to get food to survive such as sugars from fruit
Yeast breaks down to ferment the pyruvic acid into ethyl alcohol and CO2
If CO2 is released, you get regular alcohol
Ex: wine
If CO2 is not released, you get sparkling alcohol
Ex: Champagne

20. Efficiency of Glycolysis
Glycolysis uses 2 ATP in order to create G3P molecules
Makes 4 ATP at the end of the process
As a process to make energy, the efficiency is about 2%
Very low for necessary energy
This is why we need cellular respiration!!

21. The Krebs Cycle
During the Krebs Cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions
Citric Acid is created in this cycle thus giving it the nickname Citric Acid cycle
Net ATP Production is 2 ATP

22. Electron Transport Chain
The electron transport chain uses the high- energy electrons from the Krebs Cycle to convert ADP to ATP
Total ATP produced: 32

23. Aerobic Respiration Only occur in the presence of oxygen Two stages
Krebs Cycle
Electron Transport Chain with chemiosmosis
Prokaryotes
Occur in cytosol
Eukaryotes
Occur in mitochondria

24. Aerobic Respiration After glycolysis, pyruvic acids are produced
Pyruvic acid moves inside mitochondria into mitochondrial matrix (space between two membranes)
Pyruvic acid + CoA  Acetyl CoA + CO2

25. The Krebs Cycle Acetyl CoA  CO2 + H + ATP
The H produced reduce NAD+  NADH
Five steps in the Krebs Cycle
Occurs in mitochondrial matrix
Citric Acid is made in Step 1 therefore this is also called the Citric Acid cycle
Net ATP produced is 2 ATP

26. Krebs Cycle - Step 1 Acetyl CoA + oxaloacetic acid  Citric Acid
This step releases CoA back into the mitochondrial matrix for pyruvic acid to be fixed again

27. Krebs Cycle – Step 2 Citric acid releases CO2 and H
Becomes a 5-carbon compound
The H released, reduces the NAD+ to NADH

28. Krebs Cycle – Step 3 Five carbon compound releases another CO2 and H
Becomes a 4-Carbon compound
Another NAD+ is reduced to NADH
Produces an ATP

29. Krebs Cycle – Step 4 4 carbon compound releases H atom
This time, FAD is reduced to FADH2
Similar molecule to NAD+

30. Krebs Cycle – Step 5 4-Carbon compound releases H atom
Reduces NAD+ to NADH
This reaction regenerates initial oxaloacetic acid

31. Don’t let this happen to YOU!

32. Electron Transport Chain
Uses the high-energy electrons from the Krebs Cycle to convert ADP to ATP
Total net ATP produced is 34!!
Prokaryotes
Occurs on cell membrane of organism
Eukaryotes
Occurs in the mitochondria
membrane called cristae

33. ETC – Step 1 NADH & FADH2 are used to power this chain of reactions
NADH & FADH2 are oxidized (lose electrons) to the electron transport chain
Also donate H atoms
NADH  NAD+
FADH2  FAD+

34. ETC – Step 2 Electrons from NADH & FADH2 are passed down chain
Lose some energy each time passed on

35. ETC – Step 3
Lost energy from electrons transferring down the chain pump protons (H+)
This creates high concentration of H+ between inner and outer membranes
Creates a concentration gradient & electrical gradient since H+ are positive

36. ETC – Step 4
Concentration & electrical gradients in membranes produce ATP molecules by chemiosmosis
ATP synthase is protein embedded in membrane that pumps protons out and creates ATP

37. ETC – Step 5 The electrons move to final acceptor down the chain
Oxygen is the final acceptor
Oxygen also accepts protons provided by NADH & FADH2
The protons, electrons, and oxygen all combine to produce H2O

38. Importance of Oxygen
The only way to produce ATP is by the movement of electrons in the ETC
Oxygen is the final acceptor
Without oxygen, the ETC would halt

39. Efficiency of Cellular Respiration
Glycolysis 2 ATP
Krebs Cycle 2 ATP
Electron Transport Chain 32 ATP
Total = 36 ATP

40. Efficiency of Cellular Respiration
Depends on conditions of the cell
How ATP are transported
Aerobic respiration is 20 times more efficient than anaerobic respiration

41. Summary Cellular respiration Glycolysis
Glucose  pyruvic acid + ATP + NADH
Aerobic respiration
Pyruvic acid  CO2 + H2O + ATP

42. Comparing Photosynthesis & Respiration
Cellular Respiration
Function
Energy Storage
Energy Release
Location
Chloroplasts
Mitochondria
Reactants
CO2 and H2O
C6H12O6 and O2
Products
Equation
6CO2 + 6H2O  C6H12O6 + 6O2
C6H12O6 + 6O2
6CO2 + 6H2O