Download Chap 4 Metabolism

Chapter 4: Metabolism
Cellular
Respiration
Section 9-1
Feel the Burn
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.
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.
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
Section 9-1
Cellular Respiration:
An Overview
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
Glycolysis
• 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
What happens after glycolysis???
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
What happens after glycolysis???
Glycolysis is ALWAYS the first step in the break
down of glucose.
If oxygen is NOT present, glycolysis is followed
by anaerobic respiration (Fermentation)
• Alcoholic Fermentation
• Lactic Acid Fermentation
If oxygen is present, glycolysis is followed by
aerobic respiration – a process that requires
oxygen
Anaerobic Respiration: Fermentation
• What is fermentation?
– Fermentation is a process by which cells release energy
in the absence of oxygen.
• Where does fermentation occur in the cell?
– 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 Yeasts and other microorganisms use alcoholic fermentation
o 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 is ALWAYS the first step in the break
down of glucose.
Glycolysis
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.
The Krebs Cycle and Electron Transport
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
aerobic
be _________.
The Krebs Cycle and Electron Transport
Where do the reactions of
the Krebs cycle take place
in the cell???
Mitochondrial
matrix
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
energy-extracting 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
Transfer of Energy to ATP
• Where does the energy in food go?
– When broken down, the energy gets stored in
a molecule known as ATP
– ATP delivers energy wherever it is needed in
the cell. For example:
• ATP drives muscle movement
• Transport of molecules across the cell membrane
• ATP drives cellular respiration
• How does ATP deliver energy to the
cell? It is in it’s structure
ATP
• Is a nucleotide
• Adenosine TriPhosphate
• It is made of:
– a nitrogen base (adenine)
– a sugar (ribose)
–three phosphate groups
• When the third phosphate
group of ATP is removed by
hydrolysis, energy is
released.
–Hydrolysis = when a
molecule is broken down by
adding water.
ATP + H2O
ADP + P + energy
• ADP is Adenosine DiPhosphate
• P is a phosphate
•ATP is constantly recycled!