Download Cellular Respiration

Do our cells breathe?
…Using glucose to make energy (ATP)
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If plants need ATP (energy) to form glucose,
how can glucose be a source of energy for plants
and animals?
How does our body use glucose to make
energy?
Why do your muscles get really sore when you
exercise intensely, but not when you pace
yourself?
How do you get wine from grapes?
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Plants get energy from the sun and store it in the
bonds of ___________.
glucose
•
How do we get energy?
–
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by eating food.
What types of food provide
the most energy?
–
Carbs (sugars or glucose) have
the most energy
• e.g. candy bars, wheat, potatoes,
rice, pasta
• What does your body do to the food you eat?
- Our body digests our food (breaks apart bonds),
releasing energy
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Breaking bonds releases energy!
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Energy is “stored” in the glucose bonds; breaking
them releases the energy
What form of energy do our cell (and our
body) use?
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the molecule ATP
So.. our body breaks down
glucose and uses it to make ATP (ENERGY!)
 Which organelle is
responsible for producing
energy for our cells?
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The MITOCHONDRIA
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ATP (adenosine
triphosphate) is a nucleic
acid that can transfer
energy within the cell.
Ex: a small amount of
energy from a glucose
molecule can be used
directly…
The extra energy is
transferred to ATP.
The energy in ATP is
stored in the bonds
between the phosphates
(ATP has 3 phosphates).
http://www.brooklyn.cuny.edu/bc
/ahp/LAD/C7/graphics/C7_atp_2
.GIF
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Remember…cellular respiration is using glucose to
make energy
Step 1: glycolysis
 glyco = refers to glucose
 lysis = break apart
 Glycolysis = break down 1 glucose into 2
pyruvic acid molecules, which have three
carbons each (splits glucose in half)
 Also makes 2 ATP! 
Takes place in the cytoplasm
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Why would we need to break down glucose in
the cytoplasm first before we use it in the
mitochondria? (think transport)
Glucose molecules are too large to move into
the mitochondria, so glycolysis makes them
smaller to get through the mitochondria’s
membranes
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After glycolysis, there are two possible paths:
Aerobic respiration – requires oxygen
Anaerobic respiration – does not require
oxygen; happens if oxygen is lacking
Oxygen?
Aerobic
Respiration
Anaerobic
Respiration
An aerobic process (requires oxygen).
 Reaction releases energy from the chemical bonds
of carbohydrates.
 Takes place in the mitochondria.
 Equation:
6O2 + C6H12O6
6H20 + 6CO2 + 36ATP
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Oxygen + Glucose
Water + Carbon Dioxide + Energy
Equation for photosynthesis:
Energy + 6H2O + 6CO2
C6H12O6 + 6O2
Equation for aerobic cellular respiration:
6O2 + C6H12O6
6H20 + 6CO2 + 36ATP
http://www.channelislandsrestoration.com/photos/images/Isl
andFox1.jpg
http://www.rhs.org.uk/chelsea/2005/exhibitors/plants/images/GlebeCott
agePlants.jpg
http://www.ucmp.berkeley.edu/fungi/basidio/mushroomsismall.jpg
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Plants
Animals
Fungi
Protists
Some bacteria
…almost everything alive!
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Recap: Step 1 = glycolysis – 2 ATPs produced in
cytoplasm and enter mitochondria.
For aerobic respiration, in mitochondria:
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Step 2 = Krebs Cycle (Citric Acid Cycle) – in matrix
Step 3 = Electron Transport Chain – in inner membrane
ATP is generated in each step, but most of the
ATP is made in the
Electron Transport Chain
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Right before the Krebs Cycle, the Pyruvate from
glycolysis is converted to Acetyl-CoA.
During Krebs, the Acetyl-CoA is broken down
into CO2 & electrons (H+).
2 ATP are created.
The electrons then
move on to the
Electron Transport
Chain.
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We start with one molecule of glucose and end up
with 6 CO2 molecules, a handful of electrons (H+)
and 4 ATP molecules.
The CO2 is waste that will move out of the cell (and
which you exhale).
The 4 ATP molecules can be used by the cell as
energy.
What about the other 32 ATPs from our equation?
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Embedded in the mitochondria inner membrane are
proteins called electron carriers.
The electrons (H+) from Glycolysis and the Krebs Cycle
are passed from electron carrier to electron carrier (like a
bucket brigade).
With every pass,
energy is released
from the electrons,
and ATP is made.
As a result, 32 ATP
are made in the
Electron Transport
Chain.
C6H12O6
Glucose
+
6O2
→
6CO2
+
6H2O
+ 36 ATP
+ Oxygen → Carbon dioxide + Water + ATP
(Krebs Cycle)
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What happens with respiration of lipids, proteins,
and nucleic acids?
Starch: broken down into glucose, which enters
glycolysis
Fats: broken down into fatty acids and glycerol;
fatty acids are cut into 2-carbon compounds,
converted to Acetyl-CoA, and enter the Krebs Cycle
Proteins: broken down into amino acids, which can
be converted into Acetyl-CoA or other compounds
that enter the Krebs cycle at various points
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The amino group is removed & excreted as urea.
Nucleic Acids
Nucleotides
Proteins
Carbohydrates
Lipids
Sugars
Fatty Acids/
Glycerol
Amino Acids
Pyruvate
Acetyl-CoA
Krebs
Cycle
Urea
H2O
CO2
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During aerobic respiration, where do the
electrons (H+) end up as they are passed from
protein to protein?
They end up in the loving arms of oxygen.
When oxygen accepts electrons, water is made.
If oxygen wasn’t there to accept the electrons,
the Electron Transport Chain would get backed
up, and no energy would be produced.
What type of respiration happens when there is
no oxygen? …and where does it happen?
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AKA: fermentation
Two types:
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Alcohol fermentation
Lactic acid fermentation
Both take place in the
cytoplasm.
Each creates 2 ATP from
each pyruvic acid
molecule.
http://www.schmohz.com/images/beerfermenter.jpeg
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Yeast can do aerobic
or anaerobic
respiration.
Grapes turn to
alcohol by adding
yeast in containers
with out oxygen.
Bread rises because
yeast gives off CO2
bubbles while
fermenting in dough.
http://www.utoronto.ca/greenblattlab/images/a/yeast%201.jpg
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When humans (and other
animals) exercise intensely, their
muscles often use more O2 than
is available
When O2 runs out, muscles
switch to anaerobic respiration
to try to keep up with energy
demand.
This is lactic acid fermentation.
The build up of lactic acid is
what makes your muscles sore.
http://www.donlemmonsknowhow.com/img/exercisesession.jpg
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You get way more ATP
from aerobic cellular
respiration than from
fermentation.
Fermentation is mostly
used to provide organisms
with short-term bursts of
energy when oxygen is not
available.
http://www.athleticsireland.ie/content/wpcontent/uploads/2006/08/washington.jpg