Respiration: Metabolism
Goals: Be able to…
Describe the purpose, inputs, and products of
respiration, and why it releases energy.
Differentiate between aerobic respiration and
anaerobic (fermentation).
Compare and contrast bread baking, beer
brewing, and wine making.
Explain why malting is an important step in beer
brewing.
carbohydrate (sugar) Æ ATP + heat
Aerobic: (with oxygen)
sugar + O2 Æ CO2 + H2O + ATP + heat
Anaerobic: (without oxygen)
sugar Æ side product + less ATP + heat
Describe why beer brewing and wine making
have different steps.
Connect respiration to these processes.
Metabolism and 2nd Law of Thermodynamics…
Sugar (single
big molecule)
This reaction
releases energy…
Cellulose
CO2+H2O
Energy
CO2 + H2O
Breaking things down releases energy
But how can we put the energy to work?
Energized
Enzyme
ATP
Enzyme
ADP
ATP energizes enzymes and chemical reactions
by losing a P
Adenosine triphosphate: body’s energy
currency
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Sugar (single
big molecule)
ATP
Energy from
breaking
down sugar
ADP
ATP
P
CO2 + H2O
Respiration: Metabolism
carbohydrate (sugar) Æ ATP + heat
RESPIRATION!
Aerobic: (with oxygen)
sugar + O2 Æ CO2 + H2O + ATP + heat
Energy from
digestion
Anaerobic: (without oxygen)
sugar Æ side product + less ATP + heat
Respiration: Metabolism
carbohydrate (sugar) Æ ATP + heat
Aerobic: (with oxygen)
carb
sugar + O2 Æ CO2 + H2O + ATP + heat
Anaerobic: (without oxygen)
sugar Æ side product + less ATP + heat
Mitochondria: “powerhouses” of the cell. Help
transform sugar to ATP
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Anaerobic: (without oxygen)
sugar Æ side product + less ATP
The process of respiration could be described
as
A. A slow burn
Ethanol: CH3CH2OH +
some CO2
Lactic acid: C3H6O3
B. Creating energy from nothing
C. Digestion
D. Using ATP to create sugars
Anaerobic respiration (fermentation) cannot
completely break down the sugar to CO2 Æ
Less energy
You seal some dead crickets and some live
crickets in 2 different glass jars. Both kinds of
crickets are given food. Which of the following
would you expect to find in the jars?
A. The dead jar would contain more CO2 than the
live jar.
B. The dead jar would contain more carbohydrates
than the live jar.
C. The live jar would contain more O2 than the live
jar.
Why did you need to seal your cider + yeast
solution so that no air could get in?
A. The yeast would not respire if they were
exposed to air.
B. No CO2 would be produced if the yeast were
exposed to air.
C. Yeast only produce alcohol when there is no
oxygen.
D. Yeast only consume sugars if there is no
oxygen.
D. None of the above.
Yeast metabolism in bread making
Ethanol +
CO2
Sugar/
flour
Gluten protein mixture
in wheat captures CO2
bubbles
Saccharomyces
cerevisiae
Yeast keeps ATP for itself
Waste = alcohol + carbon dioxide
evaporates
leavening
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The first record of bread: Egyptian hieroglyphs
Bread pots
Guy with bread pot
Replicating ancient Egyptian bakery
Baking bread
4
How did Egyptians
figure this out?
Wild yeast is in the air
all around us
Water
Flour
Fermenting starter
In bread:
CO2 waste leavens
Ethanol waste burns off
In beer:
CO2 waste carbonates
Ethanol remains
Gruel: the first beer
Malting and mashing: creating sugar from grain
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Malting: Making yeast food
Releasing sugar from grain
Malting: Making yeast food
Starch
Starch
Germinate barley to
release enzymes
that break starch
into sugar
Embryo
Embryo
Embryo releases enzymes that break starch into
simple sugars
Kilned
Roasted
Heat barley
In the malting house…
Heated in mash tun so that enzymes can fully
break down starch into sugar
Why…?
Wort
Enzymes are
still OK
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Mixture is boiled in kettle to kill enzymes,
natural bacteria/yeasts: “brewing”
Hops added at
boil
Cooled, and specific yeast added
Summarize the basic process of beer brewing in
your own words
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Squeezing fruits
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Crush grapes
Must (= wort in beer) = sugary solution
Sanitize and add
specific yeast Æ
Ferment
Ferment with natural
yeast from grapes
Yeast lives on fruit skins
Why aren’t grapes malted like barley is for beer?
Why aren’t grapes malted like barley is for beer?
White vs. Red
White
grapes
Skins
excluded
Skins/stems
included in
fermentation
How is champagne made?
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Grape phylloxera attacks
grape roots
Grafting to resistant American root
stocks saved European grapes
Which of the following do beer and bread making
have in common?
A.Grain enzymes break down stored starches into
sugar
B.Yeast produces alcohol
C.Carbon dioxide is trapped by gluten proteins
D.Yeast is alive when the product is consumed
Yeast can conduct both aerobic and anaerobic
respiration, depending upon oxygen availability.
Could a solely aerobically-respiring yeast be used
to produce wine?
What about bread?
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