CELLULAR RESPIRATION
• Let’s take a look back!
– Photosynthesis: light energy makes glucose
(chemical energy)
• Occurs only in plants or organisms with plastids like
chlorophyll
• Carbon dioxide is taken in
• Oxygen is given off
• Also requires light & H2O
CELLULAR RESPIRATION
• Cellular Respiration: chemical process
where carbohydrates are broken down to be
a quick source of ATP
– Location: mostly within Mitochondria, first
part in cytoplasm
– CPE (Food)  CPE (ATP)
CELLULAR RESPIRATION
•
Two Types:
1. Aerobic: needs Oxygen
2. Anaerobic: does NOT need
Oxygen
•
3 Stages:
1. Glycolysis
2. Citric Acid Cycle (Krebs
Cycle)
3. Electron Transport Chain
CELLULAR RESPIRATION
•
3 Stages:
1. Glycolysis = ANAEROBIC
2. Citric Acid Cycle (Krebs Cycle) = AEROBIC
3. Electron Transport Chain = AEROBIC
CELLULAR RESPIRATION
1. Glycolysis: means “breaks down glucose”
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Occurs in cytoplasm
COSTS 2 ATPs to start reaction
Breaks glucose down to Pyruvic Acid
(pyruvate) (goes to Krebs Cycle)
Makes total of 4 ATPs
At end of reaction, net of 2 ATP available to
cell, and NADH (energy carrier – will go to
ETC)
NOT EFFICIENT
CELLULAR RESPIRATION
STOP AND REVIEW
• What is the purpose of glycolysis?
– To break down glucose into 2 pyruvate
• Is glycolysis aerobic or anaerobic?
– anaerobic
• Where does glycolysis occur?
– cytoplasm
• How many ATP are required to start glycolysis?
– 2
• What is the total number of ATP produced? Net amount of
ATP produced?
– 4, 2
CELLULAR RESPIRATION
2. Citric Acid Cycle (Krebs Cycle)
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Occurs in Mitochondria (matrix: space
enclosed by inner membrane)
Aerobic
2 Cycles occur at same time (1 for each
pyruvate)
Each cycle produces 1 ATP
CELLULAR RESPIRATION
2. Citric Acid Cycle (Krebs Cycle)
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Yields (Produces):
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2 Net ATP
NADH and FADH2
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Go to ETC
Carbon Dioxide
–
Released as waste
CELLULAR RESPIRATION
STOP AND REVIEW
• What is another name for the Krebs Cycle?
– Citric Acid Cycle
• Where does the Krebs Cycle occur?
– Mitochondrial matrix
• Is the Krebs cycle aerobic or anaerobic?
– aerobic
• What is produced?
– NADH, FADH2, 2 ATP, CO2
CELLULAR RESPIRATION
3. Electron Transport Chain
-Takes place in and across inner membrane of
mitochondria.
• NADH from glycolysis & Krebs and FADH2
from Krebs unloads electrons at ETC. Energy
used to make ATP.
• Result: 32 ATP is made
•
H2O also made
STOP AND REVIEW
• Where does the ETC take place?
– Inner membrane of mitochondria
• Is the ETC aerobic or anerobic?
– aerobic
• Where does the energy come from to make
ATP?
– NADH and FADH2
• What is made during the ETC?
– 32 ATP, Water
CELLULAR RESPIRATION
• END RESULT:
– 36-38 ATP made from all 3 Stages
– Oxidative Phosphorylation
• Oxygen is final electron acceptor; water is formed
• ADP is converted to ATP by adding phosphate
group
• But wait! What if there was not enough
oxygen? Could cellular respiration still
have taken place?
CELLULAR RESPIRATION
• YES! Anaerobic Respiration or
FERMENTATION takes place!
CELLULAR RESPIRATION
•
FERMENTATION
–
2 Kinds:
1. Lactic Acid
2. Alcoholic
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Both kinds only use GLYCOLYSIS
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How many ATPs does that mean they make?
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2 net ATP
CELLULAR RESPIRATION
1. Lactic Acid Fermentation
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Anaerobic
Produces burning feeling in
muscle cells
Occurs when body worked to
point that more oxygen being
used than taken in
Produces LACTIC ACID
and 2 ATP
CELLULAR RESPIRATION
2. Alcoholic
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Anaerobic
Carried out by some bacteria
and yeast
Used to bake bread and make
wine
Produces CO2, Ethyl Alcohol,
and 2 ATP
STOP AND REVIEW
• Where in the cell does fermentation take place?
– Cytoplasm
• Why does fermentation occur?
– Not enough oxygen or no mitochondria
• What organisms go through alcoholic fermentation?
– Yeast and some bacteria
• How many ATP does fermentation produce?
– 2 net ATP
Let us do some comparisons!
• Photosynthesis vs. Cellular Respiration
Photosynthesis
Cellular Respiration
Food synthesized
Food broken down
Energy from sun stored in glucose
Energy of glucose released
Carbon dioxide taken in
Carbon dioxide given off
Oxygen given off
Oxygen taken in
Produces sugars
Produces CO2 and H2O
Requires light
Does not require light
Occurs only in presence of
chlorophyll
Occurs in all living cells
Let us do some comparisons!
• Fermentation vs. Cellular Respiration
Comparison of Fermentation to Cellular Respiration
Lactic Acid
glucose
glycolysis (pyruvic acid)
Alcoholic
Cellular respiration
glucose
glucose
glycolysis (pyruvic acid)
glycolysis (pyruvic acid)
carbon dioxide
carbon dioxide
lactic acid
alcohol
water
2 ATP
2 ATP
36 ATP
Check It!
1. The process by which mitochondria break
down food molecules to produce ATP is
called ________.
A. photosynthesis
B. cellular respiration
C. the light-independent reaction
D. the Calvin cycle
Check It!
2. The three stages of cellular respiration in order
are ________.
A. Carbon fixation, the Calvin cycle, and the
electron transport chain
B. glycolysis, the citric acid cycle, and the
electron transport chain
C. glycolysis, the electron transport chain, and
the citric acid cycle
D. the light-dependent reactions, the citric acid
cycle and the electron transport chain
Check it!
3. Which of the following yields the greatest net
ATP?
A. Lactic acid fermentation
B. Alcoholic fermentation
C. Calvin cycle
D. Cellular respiration