Aerobic respiration as the release of a
relatively large amount of energy in cells by the
breakdown of food substances in the presence of
oxygen
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Word equation for aerobic respiration:
Glucose + Oxygen -> Carbon Dioxide + water +
Energy
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Equation for aerobic respiration using symbols:
(C6H12O6 + 6O2 → 6CO2 + 6H2O+ energy in ATP
form)
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Anaerobic respiration as the release of a relatively
small amount of energy by the breakdown of food
substances in the absence of oxygen
Word equation for anaerobic respiration
in muscles during hard exercise:
(glucose → lactic acid)
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Balanced equation for anaerobic respiration in
muscles:
(C6H12O6 → 2C3H6O3)
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 microorganism
yeast:
(glucose→ alcohol + carbon dioxide)
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(C6H12O6 →2C2H5OH + 2CO2)
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Anarobic Respiration in yeast during brewing:
- Yest is used in the production of several types
of beers including lagers. And ales .
Yeast is cultured in huge bins under anaerobic
conditions.
Yeast converts the sugar in grapes to alcohol
and carbon dioxide.
A one-way valve allows the carbon dioxide to
escape without letting any oxygen in.
The bubbles are left dissolved in the bins when
making sparkling wines such as Champagne
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One yeast cell can approximately ferment its own
weight in glucose in an hour. The yeast can produce an
average of 15 to 16% of ethanol by weight.
Yeast can produce up to 18 percent ethanol, by
volume
Any more ethanol is toxic to the cells and causes yeast
cell to die.
Sulphur dioxide is added to kill naturally present
bacteria and moulds.
There are basically two major kinds of yeast used in
brewing. Ale yeast works at about room temperature,
ferments quickly, and produces the pleasant "fruitiness"
characteristic of most ales.
Lager yeast works at cold temperatures (30 to 40
degrees Fahrenheit), ferments more slowly, and
produces the clean taste of a lager beer. Within each
of these two types are literally hundreds of different
strains of yeast.
The tantalizing aroma of bread baking in
the bakery is due to a process called
fermentation of baker's yeast
 Yeast have long been utilized to ferment
the sugars of rice, wheat, barley, and
corn to produce alcoholic beverages
and in the baking industry to expand, or
raise, dough.
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Dry yeast available in the grocery store is a collection
of dormant yeast spores.
Once these spores are mixed into water and dough,
the culture is active.
To start this germination process and make the
bread rise faster, the baker sometimes mixes yeast
with water or milk before adding to the dough.
The yeast's function in baking is to ferment sugars
present in the flour or added to the dough.
This fermentation gives off carbon dioxide and
ethanol.
The carbon dioxide is trapped within tiny bubbles
and results in the dough expanding, or rising.
Their usefulness is based on their ability to convert
sugars and other carbon sources into ethanol in the
absence of air (anaerobic), and into carbon dioxide
and water in the presence of air (aerobic).
Our muscles can run out of oxygen when
we work hard
 They can keep going by respiring
anaerobically for a short time
 When anaerobic respiration happen in
humans lactic acid is produced
 Lactic acid is toxic
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When it builds up in muscle – it is painful
and causes cramps
 This is why muscles can respire for a short
time anaerobically
 Lactic acid diffuses into blood from
muscles and is taken to the liver because
extra oxygen is needed
 This is why we start panting – to get more
oxygen
 You are paying your “oxygen debt”
while your muscles were respiring
anaerobically
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