Chapter 9 Notes
Cellular Respiration
9-1 Chemical Pathways
All living organisms need food to survive.
Food provides living things with the
chemical building blocks they need to
grow and reproduce.
9-1 Chemical Pathways
1 gram of glucose releases 3811 calories
of heat energy
Calorie (c): the amount of energy
needed to raise the temperature of 1
gram of water 1 Celsius degree
The calories on food labels (C) are
kilocalories or 1000 calories
9-1 Chemical Pathways
Cells gradually release energy from
glucose and other food compounds.
Cellular respiration is the process that
releases energy by breaking down food
molecules in the presence of oxygen.
- 3 parts: glycolysis, the Krebs cycle,
and the electron transport chain
Electrons carried in NADH
Pyruvic acid
Glucose
Glycolysis
Krebs Cycle
Electrons
carried in
NADH and
FADH2
Cytoplasm
Mitochondrion
Electron
Transport Chain
9-1 Chemical Pathways
Equation for Cellular Respiration
6O2 + C6H12O6  6CO2 + 6 H2O + Energy
oxygen+glucose carbon+water+energy
dioxide
9-1 Chemical Pathways
Glucose
Glycolysis
Krebs
cycle
Fermentation
(without oxygen)
Electron
transport
Alcohol or
lactic acid
9-1 Chemical Pathways
The first set of chemical reactions in
cellular respiration is glycolysis.
Glycolysis is the process in which one
molecule of glucose is broken in half,
producing two molecules of pyruvic
acid, a 3-carbon compound
9-1 Chemical Pathways
Net results of glycolysis
- 2 molecules of ATP are gained
- 2 molecules of NADH are gained
- 2 molecules of pyruvic acid (3C) are
formed from 1 glucose molecule
9-1 Chemical Pathways
2 ATP
2 ADP
4 ADP
4 ATP
Glucose
2 Pyruvic
acid
9-1 Chemical Pathways
When oxygen is present in the cell,
glycolysis is followed by the Krebs cycle.
If there is no oxygen present, glycolysis
is followed by fermentation.
Fermentation releases energy from food
molecules in the absence of oxygen
9-1 Chemical Pathways
Because fermentation does not require
oxygen it is said to be anaerobic.
The two main types of fermentation are
alcoholic fermentation and lactic acid
fermentation
9-1 Chemical Pathways
9-1 Chemical Pathways
9-1 Chemical Pathways
Alcoholic fermentation is used mainly by
plants and yeasts
- alcohol is the product
Lactic acid fermentation occurs in muscle
cells when the body cannot supply
enough oxygen to the tissues
- lactic acid is the product
Section Quiz
The raw materials required for cellular respiration
are




carbon dioxide and oxygen.
glucose and water.
glucose and oxygen.
carbon dioxide and water.
Section Quiz
Glycolysis occurs in the




mitochondria.
cytoplasm.
nucleus.
chloroplasts.
Section Quiz
The net gain of ATP molecules after glycolysis is




3
2
3
4
ATP molecules.
ATP molecules.
pyruvic acid molecules.
pyruvic acid molecules
Section Quiz
Fermentation releases energy from food
molecules in the absence of




oxygen.
glucose.
NADH.
alcohol.
Section Quiz
The first step in fermentation is always




lactic acid production.
the Krebs cycle.
glycolysis.
alcohol production.
9-2 The Krebs Cycle and
Electron Transport
Oxygen is used for the final steps of
cellular respiration. Because the
pathway requires oxygen, it is said to
be aerobic.
In the presence of O2, pyruvic acid passes
on to the second stage of cellular
respiration, the Krebs cycle
9-2 The Krebs Cycle and
Electron Transport
During the Krebs cycle, pyruvic acid is
broken down into carbon dioxide in a
series of energy-extracting reactions
Net result of the Krebs cycle
- 2 molecules of pyruvic acid enter
- 8 molecules of NADH are gained
- 2 molecules of FADH2 are gained
- 2 molecules of ATP are gained
Mitochondrion
Citric Acid
Production
9-2 The Krebs Cycle and
Electron Transport
From glycolysis and the Krebs cycle high
energy electron carriers, NADH and FADH2,
are produced. The electrons are then
passed to the electron transport chain.
The electron transport chain uses high
energy electrons to convert ADP to ATP.
ETC Movie pt 1
ETC Movie pt 2
9-2 The Krebs Cycle and
Electron Transport
9-2 The Krebs Cycle and
Electron Transport
9-2 The Krebs Cycle and
Electron Transport
9-2 The Krebs Cycle and
Electron Transport
ATP
synthase
9-2 The Krebs Cycle and
Electron Transport
Channel
ATP
synthase
ATP
9-2 The Krebs Cycle and
Electron Transport
Each NADH make 3 ATP while each
FADH2 makes 2 ATP
1 glucose molecule can then make
38 total ATP ( 4 ATP, 10 NADH  30
ATP, 2 FADH2  4 ATP)
Cellular Respiration Animation
Section Quiz
The Krebs cycle breaks pyruvic acid down into




oxygen.
NADH.
carbon dioxide.
alcohol.
Section Quiz
In eukaryotes, the electron transport chain is
located in the




cell membrane.
inner mitochondrial membrane.
cytoplasm.
outer mitochondrial membrane.
Section Quiz
To generate energy over long periods, the body
must use




stored ATP.
lactic acid fermentation.
cellular respiration.
glycolysis.
Section Quiz
Which statement correctly describes
photosynthesis and cellular respiration?




Photosynthesis releases energy, while cellular
respiration stores energy.
Photosynthesis and cellular respiration use the same
raw materials.
Cellular respiration releases energy, while
photosynthesis stores energy.
Cellular respiration and photosynthesis produce the
same products.