Download Chapter 9 Cellular Respiration and Fermentation

Chapter 9
Cellular Respiration and
Fermentation
9.1 Cellular Respiration: An Overview
 Do you like to run, bike, or swim? These all are good
ways to exercise. When you exercise, your body uses
oxygen to get energy from glucose.
1. How does your body feel at the start of exercise, such
as a long, slow run? How do you feel 1 minute into
the run; 10 minutes into the run?
2. What do you think is happening in your cells to cause
the changes in how you feel?
3. Think about running as fast as you can for 100
meters. Could you keep up this pace for a much
longer distance? Explain your answer.
 When you are hungry, how do you feel?
 Imagine you are taking a test hungry, think you will
do well on the test?
 What’s the opposite of an autotroph?
Chemical Energy and Food
 What are the 4 macromolecules?
 Carbs, proteins, lipids, nucleic acids.
 Organisms get their energy from food.
 Calorie:
 Amount of energy needed to raise the temperature of
1 gram of water 1 degree Celsius.
 Our body breaks down food molecules gradually,
capturing a little bit of chemical energy at key steps.

Through cellular respiration, oxygen is used to
release energy from glucose and produce
ATP.
Overview of Cellular Respiration

What is cellular respiration?

Cellular respiration is the process that releases energy by
breaking down food (glucose) in the presence of oxygen.
C6H12O6
glucose

+
6 O2
oxygen

6 H2O + 6 CO2 + Energy
water carbon
ATP
dioxide
What would be the problem if cellular respiration occurred
in just one step?

Burn up all energy instead of a gradual release of energy
Stages of Cellular Respiration
 We have three stages of cellular respiration.
 1. Glycolysis
 2. Krebs Cycle
 3. Electron Transport Chain
Cellular Respiration:
An Overview
Section 9-1
Electrons carried in
NADH
Pyruvic
acid
Glucose
2
Krebs
Cycle
Glycolysis
2
Electrons
carried in
NADH and
FADH2
Electron Transport
Chain
32
36 Total ATP
Oxygen and Energy
 Aerobic:
 “with air” Requires oxygen.
 Think aerobics, people who work out need more
oxygen!
 Anaerobic:
 “without air” Does not require oxygen.
 Which process do you think gets the most ATP?
Comparing Photosynthesis and Cellular
Respiration
 Photosynthesis removes carbon dioxide from the
atmosphere, and cellular respiration puts it back.
Photosynthesis release oxygen into the atmosphere,
and cellular respiration uses that oxygen to release
energy from food.
9.2 The Process of Cellular Respiration
 First step in cellular respiration
 Glyco / lysis – “to break glucose”
 Does not need oxygen to occur
 Where does glycolysis take place in the cell?
 Glycolysis occurs in the cytoplasm of the cell.
 Glycolysis
 Process in which one molecule of glucose is broken in half,
producing two molecules of pyruvic acid.
Glycolysis
• How does the cell get glycolysis going?
 The cell uses energy. 2 molecules of ATP are used up.
• What are the products of glycolysis?
 Pyruvate and 4 ATP molecules
C. Glycolysis
• Why is there only a NET of 2 ATP molecules
produced during glycolysis?
 2 ATP molecules were used to start reaction
The Krebs Cycle and Electron Transport
After glycolysis, we move to the Krebs Cycle.
Krebs Cycle:
Second stage of cellular respiration. Pyruvic acid is broken down
into co2.
1.
At the end of glycolysis, how much of the chemical energy
in glucose is still unused?
Approx. 90%
2.
Because the final stages of cellular respiration require
oxygen, they are said to be aerobic.
The Krebs Cycle and Electron Transport
Where do the reactions of
the Krebs cycle take place
in the cell???
Mitochondrial matrix
(inner most compartment
of the mitochondria)
The Krebs Cycle and Electron Transport
 The Krebs Cycle

Second stage of cellular
respiration, in which pyruvic
acid is broken down into carbon
dioxide in a series of energyextracting reactions
Electron Transport Chain
Where do the reactions of
the electron transport
chain take place in the
cell???
Inner membrane of
mitochondria
The Electron Transport
 The Electron Transport Chain
 series of proteins in which the high-energy electrons from the
Krebs cycle are used to convert ADP into ATP
Cellular Respiration and Energy
In the presence of
oxygen, the cell can
produce 36 ATP
molecules per one
glucose molecule
9.3 Fermentation
Glycolysis is ALWAYS the first step in the break down of
glucose.
 Glycolysis does not need oxygen to occur
If oxygen is NOT present, glycolysis is followed by anaerobic
respiration.
Alcoholic Fermentation
 Lactic Acid Fermentation

Anaerobic Respiration: Fermentation

What is fermentation?


Where does fermentation occur in the cell?


Fermentation is a process by which cells release energy in the absence
of oxygen.
Cytoplasm of the cell.
Why is fermentation considered an anaerobic process?


Anaerobic is process that does not require oxygen
Fermentation does NOT require oxygen
Anaerobic Respiration: Fermentation
 Two main types of fermentation
1.
Alcohol fermentation
2.
Lactic acid fermentation
Glycolysis
Alcoholic Fermentation
 What organisms use alcoholic fermentation
o
o
Yeasts and other microorganisms use alcoholic fermentation
Waste products are alcohol and carbon dioxide
 What happens to the small amount of alcohol produced
during the baking of bread?

Evaporates when bread is baked.
Glycolysis
Alcoholic Fermentation
 How does fermentation allow the production of ATP to
continue?

NAD+ is looped to start the process over again.
Glycolysis
Lactic Acid Fermentation
Section 9-1
Glucose
2 Pyruvic acid
2 Lactic acid
2. Lactic Acid Fermentation –
• Lactic acid is produced by your muscles during
rapid exercise when not enough oxygen is present.
• Prokaryotes produce lactic acid as a waste product
which is used in production of foods: yogurt,
cheese, sour cream, sauerkraut, etc.
SUMMARY
Glycolysis
Glycolysis is ALWAYS the first step in the break down of
glucose.
If oxygen is NOT present, glycolysis is followed by anaerobic
respiration.
Alcoholic Fermentation
 Lactic Acid Fermentation

If oxygen is present, glycolysis is followed by aerobic
respiration.
Energy and Exercise
 For short, quick bursts of energy, the body used ATP
already in muscles as well as ATP made by lactic acid
fermentation.
 For exercise longer than about 90 seconds, cellular
respiration is the only way to continue generating a
supply of ATP.
 Jay airplane story