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Chapter 7
Respiration
 Cellular Respiration (p 222)
process that releases energy… by breaking
down glucose (sugar)… and other food
molecules… in the presence of oxygen
 Energy is released in a SLOW controlled way
 Video


http://videos.howstuffworks.com/hsw/12580-thescience-of-life-cellular-respiration-video.htm
3 stages of Cellular Respiration
 (Each step captures some energy and
makes it ATP)
Glycolysis
Krebs Cycle
Electron Transport
Chain
Fermentation
Glycolysis
 1 molecule of glucose is broken
down in ½ , producing 2 molecules
of pyruvic acid and a 3 carbon
compound-

FACTS
1st step of cell resp.
 2 ATP molecules into its “account” to get
glycolysis going
 Energy releasing process (2ATP→4ATP)
 Amount of energy made is small- but
happens quickly

 1,000’s of ATP made in a few milli-seconds

Takes place in cytoplasm
 The formula for aerobic cellular respiration is
 C6H12O6 + O2 → CO2 + H2O + Energy (as
ATP)
 The word equation for this is:
 Glucose + Oxygen → Carbon dioxide + Water
+ Energy (as ATP)
 http://www.biologyinmotion.com/atp/index.htm
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 ATP- charged battery
 ADP uncharged battery
No oxygen?
 During fermentation:
cells convert NADH to NAD+ by
passing high-energy electrons back to
pyruvic acid.
 This action converts NADH back into
the electron carrier NAD+,
 …..allows glycolysis to continue
producing a steady supply of ATP.

Fermentation
 Sore Muscles, wine and beer, bread…
 Def: releases energy from food by
making ATP WITHOUT oxygen
(anaerobic)
 2 types
 Alcoholic Fermentation
 Lactic Acid Fermentation
Alcoholic
 Used by yeast and other microbes
 Causes dough to rise
 CO² is released ( this is why bread has
spaces)
 Make wine? Yeast, grapes, sugar and
dark place cool place….and a way for
Co2 bubbles to escape-
Lactic Acid Fermentation
 Pyruvic acid → Lactic Acid
 Vigorous Exercise…(sprinting)
 after a while oxygen cannot
reach the muscles fast enough
and you run out…
 so in order to keep going
anyway…your muscles keep
producing ATP thru Lactic Acid
Fermentation…
 sore muscles
 Uni-cellular org produce LA as a waste during
fermentation




Kimchi
Cheese
Yogurt
Buttermilk
Have Oxygen ?
 At the end of glycolysis, about 90 percent of the
chemical energy that was available in glucose is
still unused, locked in the high-energy electrons of
pyruvic acid.
 To extract the rest of that energy, the cell turns to one
of the world's most powerful electron acceptors—
oxygen.
 Oxygen is required for the final steps of cellular
respiration. Because the pathways of cellular
respiration require oxygen, they are said to be
aerobic.
Krebs and electron transport
 2nd stage:
 The Krebs cycle is named after Hans Krebs,
the British biochemist who demonstrated its
existence in 1937.
 During the Krebs cycle, pyruvic acid is
broken down into carbon dioxide in a
series of energy-extracting reactions.
Then….

The electron transport chain uses the
high-energy electrons from the Krebs cycle….
to convert ADP into ATP.
 See video
 http://www.biologyinmotion.com/atp/index.htm
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Aerobic vs Anaerobic Resp
 Aerobic- oxygen needed to make ATP

Krebs cycle
 An-aerobic- fermentation


Lactic acid
alcoholic
How much energy is in food
 Food energy is measured in calories
 Food is for



Chemical building blocks for bodies
Raw materials for new molecules
Energy
 1 gram of glucose= 3811 calories of heat
energy…… WOW???!!!!!!
WOW???!!!
 On the label, foods are actually in kilocalories
not calories
 1000 calories- 1 kilocalorie
 Hershey kiss= 22 kilo-calories REALLY
(22,000 calories)-
Calorimeter
 Calorie- amount of energy needed to raise
the temperature of 1 gram of water , up 1
degree Celsius
How efficient is the process of cellular
respiration?
 The 36 ATP molecules the cell makes per
glucose represent about 38 percent of the
total energy of glucose.
 That might not seem like much, but it means
that the cell is actually more efficient at using
food than the engine of a typical automobile
is at burning gasoline.
 What happens to the remaining 62
percent? It is released as heat, which is one
of the reasons your body feels warmer after
vigorous exercise
Equation for Respiration
 Observations?
 The formula for aerobic cellular respiration is
 C6H12O6 + O2 → CO2 + H2O + Energy (as
ATP)
 The word equation for this is:
 Glucose + Oxygen → Carbon dioxide + Water +
Energy (as ATP)
Photosynthesis vs. Respiration
 Study the relationships between the 2
Creatine (GNC- Vitamin Shoppe)
 Creatine Phosphate





Occurs naturally in muscle cells
Contains reserve of energy
Its P- group can be removed to
make more ATP, from ADP, when
there is a short supply
Will help to sustain intense activity
longer
*** Can cause kidney damage
though, if used improperly…
Start race (1 sec – 10 sec)
11 sec- 90 sec
ATP already in muscles
(STORED- only lasts a few
seconds)
ATP from fermentation (90
seconds or 50 meters)
Steady pace (2min-19 min)
ATP from Cell Resp…. energy
in muscle and tissues:
“carbohydrate glycogen”, lasts
for 15 or 20 min.
Steady Pace (20 min +)
Stored molecules (fat) used
(as energy supply
End race
Breathe deeply to remove
lactic acid- extra oxygen
needed
 Energy and ExerciseBang! The starter's pistol goes off, and
the runners push off their starting blocks and sprint down the
track. The initial burst of energy soon fades, and the runners
settle down to a steady pace. After the runners hit the finish line,
they walk around slowly and breathe deeply to catch their
breath.Let's look at what happens at each stage of the race in
terms of the pathways the body uses to release energy. To
obtain energy, the body uses ATP already in muscles and new
ATP made by lactic acid fermentation and cellular respiration. At
the beginning of a race, the body uses all three ATP sources,
but stored ATP and lactic acid fermentation can only supply
energy for a limited
 time.Quick Energy What happens when your body needs lots of
energy in a hurry? In response to sudden danger, quick actions might
make the difference between life and death. To an athlete, a sudden
burst of speed might win a race.Cells normally contain small amounts
of ATP produced during glycolysis and cellular respiration. When the
starting gun goes off in a footrace, the muscles of the runners contain
only enough of this ATP for a few seconds of intense activity. Before
most of the runners have passed the 50-meter mark, that store of ATP
is nearly gone. At this point, their muscle cells are producing most of
their ATP by lactic acid fermentation. These sources can usually supply
enough ATP to last about 90 seconds. In a 200- or 300-meter sprint,
this may be just enough to reach the finish line.Fermentation produces
lactic acid as a byproduct. When the race is over, the only way to get
rid of lactic acid is in a chemical pathway that requires extra oxygen.
For that reason, you can think of a quick sprint building up an oxygen
debt that a runner has to repay after the race with plenty of heavy
 breathing.Long-Term Energy What happens if a race is longer?
How does your body generate the ATP it needs to run 2
kilometers or more, or to play in a soccer game that lasts more
than an hour? For exercise longer than about 90 seconds,
cellular respiration is the only way to generate a continuing
supply of ATP. Cellular respiration releases energy more slowly
than fermentation, which is why even well-conditioned athletes
have to pace themselves during a long race or over the course
of a game. Your body stores energy in muscle and other tissues
in the form of the carbohydrate glycogen. These stores of
glycogen are usually enough to last for 15 or 20 minutes of
activity. After that, your body begins to break down other stored
molecules, including fats, for energy. This is one reason why
aerobic forms of exercise such as running, dancing, and
swimming are so beneficial for weight control.