RESPIRATION
Respiration is a cellular process which
provides energy. All living cells carry
out respiration. Eucaryotic cells carry
it out in the mitochondria and
procaryotic cells in the cytoplasm.
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Respiration is also known as
oxidation because it uses oxygen.
In this process glucose (sugar) is
broken down to carbon dioxide ,
water and energy.
General equation for respiration is:
C6H12O6 + 6O2
6CO2 + 6H2O + Energy
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Respiration occurs in over 50 steps
catalysed by many enzymes.
The chemical bonds held in the glucose
molecules are released and transferred to
ATP Adenosine Triphosphate (high energy)
ADP Adenosine diphosphate (low energy
molecule)
For each molecule of glucose 38 molecules
of ATP are produced.
C6H 12O 6 + 6O2 + 38ADP
6CO2+ 6 H2O + 38ATP
STAGES of Respiration
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First Stage ( glycolysis)
Occurs in cytoplasm
Glucose
2 Pyruvate + 2ATP
+
+ 2ATP
Second Stage
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When oxygen is present the cell then
undergoes aerobic respiration.
This stage occurs in the mitochondria
and uses oxygen.
Pyruvate + 3O2
3 Carbon dioxide + 3water
+
3O2
+
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3 Ho
2
Anaerobic Respiration
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When no oxygen is used or available
an alternative pathway is followed.
Lactic acid fermentation is formed by
some fungi, some bacteria like the
Lactobacillus acidophilus. in yogurt,
and sometimes by our muscles.
Lactic Acid Fermentation
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In the process of lactic acid
fermentation, the 3-carbon pyruvic
acid molecules are turned into lactic
acid .
Pyruvate incompletely broken down
to lactic acid and carbon dioxide.
Pyruvate(C3) lactic acid (C2) + Carbon Dioxide
+
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Normally our muscles do cellular
respiration like the rest of our bodies,
using O2 supplied by our lungs and blood.
However, under greater exertion when the
oxygen supplied by the lungs and blood
system can’t get there fast enough to keep
up with the muscles’ needs, our muscles
can switch over and do lactic acid
fermentation.
In the process of lactic acid fermentation,
the 3-carbon pyruvic acid molecules are
turned into lactic acid.
Alcohol Fermentation
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Alcohol fermentation is carried out by
yeast and some kinds of bacteria. The
“waste” products of this process are
ethanol and carbon dioxide (CO2).
Humans have long taken advantage
of this process in making bread, beer,
and wine.
Anaerobic Alcohol
Fermentation
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Pyruvate (C3)
Ethanol (C2OH6) + Carbon Dioxide (CO2)
+
+
2ATP