Download Cellular Respiration

Chapter 9
•Cellular
Respiration is the process that releases
energy by breaking down food molecules in the
presence of oxygen. The equation for Respiration is the
opposite of photosynthesis.
O2 + C6H12O6
CO2 + H2O + Energy
Oxygen + Glucose
Carbon Dioxide + Water + Energy
•Cellular Respiration occurs inside of the mitochondria
of the cell and it has three parts associated with it:
Glycolysis, the Krebs cycle, and the Electron
Transport Chain.
Glycolysis, the first step in respiration, occurs in
the cytoplasm. Glycolysis breaks down sugar
(C6H12O6) into two molecules (Pyruvate); the break
down of sugar produces ATP.
▪ Glycolysis is the process
in which glucose is broken
down. This process does
not require oxygen and
can occur in aerobic or
anaerobic conditions.
Remember this process
occurs in the cytoplasm.
•Remember
ATP is the short term energy source for the cell.
ATP: (Adenosine triphosphate)
ATP is a nucleotide that performs
many essential roles in the cell.
It is the major energy currency
of the cell, providing the energy for most of the energyconsuming activities of the cell.
•
Fermentation releases
energy from sugar
molecules in the absence
of oxygen.
There are two types of
fermentation: Alcoholic
and Lactic Acid
Fermentation.
This occurs in the
cytoplasm.
Alcoholic
Fermentation: Yeasts
and a few other
microorganisms use
alcoholic fermentation
to obtain energy
(ATP). The
byproducts of this process are CO2 and alcohol.
Lactic Acid Fermentation:
Our body uses this process
to free up energy when we
start to get short on
oxygen. Extreme exercise
will cause muscles to feel
pain and “burn”, which is the
lactic acid building up in your muscles.
•When there is enough oxygen present in the body than the
process of respiration continues. The two molecules
produced from the glycolysis (pyruvate) move from the
cytoplasm into the mitochondrion (power house of the
cell).
Remember the mitochondrion is a
bean shaped organelle that has an
inner membrane.
Inside the mitochondrion, the second step, the Krebs cycle
occurs. The Krebs cycle occurs in the matrix (fluid portion) of
the mitochondrion. The Krebs cycle produces more ATP, CO2, and
electron carrying molecules in the form of NADH and FADH2
(Flavin adenine dinucleotide).
It is important to note that only one ATP is produced for every
molecule of pyruvic acid. This step is really a preparation (NADH
and FADH2) for the next process which will produce a majority of
the ATP.
•The
third and final step in cellular respiration is
the Electron Transport Chain. The Electron
Transport Chain occurs in the membrane of the
mitochondrion. During this step large amounts of
ATP and also water are produced.
In the above graphic notice that NADH has an electron
stripped from the hydrogen, when this happens the
electron gets moved through a chain of proteins which
pump H+ across the membrane. The protein pumps use
the energy from the electrons to run the pump and send
H+ out. The FADH2 does the same thing (donate
electrons).
The whole point of this is to make a gradient, lots of H+ on one
side. When the gradient is established the H+ will want to move
from high to low concentration (diffusion), it does that by moving
through the enzyme ATP Synthase. When the H+ ions move
through the ATP Synthase the whole enzyme turns and
produces ATP. About 32 ATP’s are produced in this
process.
The
electrons and H+ meet up with O2 to make water
which is removed from the cell.
What happens to the H+ and electrons that are left over?
• The whole process of cellular respiration gives us 36
molecules of ATP. Remember cell respiration requires an
adequate amount of oxygen.
Energy and Exercise
Long term energy is provided by cellular respiration. For
instance, if you are running a long distance race your body uses all
of the available carbohydrates for energy; this usually last about
15-20 minutes. After that energy source is used up your body
starts to use the carbs stored in fats. This is why exercise is
helpful for weight lose.
Short term energy is provided by lactic acid fermentation, this
energy source cannot be sustained.