Respiration
The controlled release of energy from
glucose, within a cell
- 24 hour process.
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Contents
Aerobic respiration
Stage 1
Stage 2
Anaerobic respiration
Aerobic –
Biochemistry
Aerobic Vs Anaerobic
Industrial
Fermentation
Yoghurt Manufacture
Beer Manufacture
Use of Immobilised
yeast
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Aerobic respiration
The controlled release of energy from glucose,
within a cell, using oxygen.
In general (aerobic respiration):
Glucose + oxygen  Energy + waste products
Waste products = carbon dioxide + water
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Balanced equation for Aerobic
Respiration
C6H1206 + 6O2  Energy + 6CO2 + 6H20
2820 kJ
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Respiration – a one or two stage
process
Stage 1 does not require oxygen and releases
a small amount of energy – called
glycolysis.
- glucose (6 carbon carbohydrate) broken
down into two 3 carbon compounds
(pyruvate or pyruvic acid) in the cytosol
(cytoplasm minus the organelles) of the cell,
with the release of ATP.
- this process releases very little energy (2
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ATP).
Stage one –
aerobic &
anaerobic
respiration
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Respiration – a one or two stage
process
Stage 2 does require oxygen and releases a
large amount of energy.
- this process takes place in the mitochondria
of the cell.
Note: the rate of both processes are controlled
by enzymes.
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Anaerobic Respiration
The controlled release of energy from glucose,
within a cell, without using oxygen.
Oxygen may be present but oxygen will not
be used.
This is a Stage 1 process.
In general (anaerobic respiration):
Glucose  Energy + waste products
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Anaerobic Respiration – waste
products
Waste products = lactic acid
Occurs in humans – causes cramps
OR
Waste products = carbon dioxide + ethanol
Occurs in yeast – fermentation
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Balanced equations for Anaerobic
Respiration
C6H12O6  Energy + 2CH3CH(OH)COOH
150 kJ Lactic acid
C6H12O6  Energy + 2C2H5OH + 2CO2
210 kJ Ethanol
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Anaerobic respiration – summary
chart
OR
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Aerobic respiration – Stage 2
(1/3)
• Oxygen must be present.
• The pyruvate molecule (3C) enters a
mitochondrion
• The pyruvate is broken down to one
molecule of CO2 (1C) and Acetyl Coenzyme A (2C).
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Aerobic respiration – Stage 2
(2/3)
• Acetyl Co-enzyme A enters a series of
chemical reactions, Kreb’s Cycle where it is
broken down to CO2 and H.
• During Kreb’s Cycle an electron transfer
system operates to remove electrons from
the hydrogen (H+ + e-)
• Electrons from the cycle are transferred
through an electron transport chain
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Aerobic respiration – Stage 2
(3/3)
• The energy released by the transport of the
electrons is used to make ATP from ADP
and P.
ADP + P  ATP
• Finally the electrons are transferred to
oxygen which combines with hydrogen to
form water
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Stage two – summary
chart
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Types of Respiration – comparison
Aerobic
Anaerobic
Complete this yourself – a
minimum of four points
See slide 27 for solution
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Industrial fermentation
Fermentation is important in the food and
drink industries.
Brewing, baking, yoghurt and cheese making
all depend on micro-organisms fermenting
the original food to produce the desired
product.
These are examples of biotechnology.
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Complete this table
Original
food
Microorganism used
Desired
product
Brewing
Baking
Yoghurt
making
Cheese
making
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Completed table
Brewing
Baking
Yoghurt
making
Cheese
making
Original
food
Starch,
sugar
Microorganism used
Desired
product
yeast
Alcohol
Starch
yeast
Carbon
dioxide
Milk
Bacteria
Lactic acid
Bacteria
e.g. Danish
blue 19
Milk
Yoghurt Manufacture
(1/2)
• Made from milk.
• Sugar and/or powdered milk may be added.
• Skimmed milk use for making low-fat
yoghurt.
• Milk pasteurised – kills pathogenic (disease
causing) bacteria e.g. Tuberculosis bacillus,
and stops growth of bacteria that sours milk.
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Yoghurt Manufacture
(2/2)
• Milk cooled to 46°C and a starter culture of
lactic acid bacteria is added.
• Yoghurt cooled after 4 to 5 hours at 46°C –
to allow growth of yoghurt microbes.
• Fruit added – in a starch and sugar
suspension.
• Colours & flavours added.
• Packed, cool and store in fridge.
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Industrial production of Yoghurt
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Beer Manufacture
(1/2)
• Made from grain – barley – food stored as
starch in grain – contains the enzyme
amylase – enzyme produces as it
germinates.
• Grain dampened, kept warm and allowed to
germinate (= malting) – malt dried and
stored.
• Malt ground with water – allows amylase
convert starch to sugar – more barley can be
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added to increase starch supply.
Beer Manufacture
(2/2)
• Solution boiled to stop amylase activity.
• Mixture filtered.
• Hops added – for flavour and to reduce the
growth of unwanted bacteria.
• Yeast (fungus) is added – Saccharomyces
cerevisiae – fermentation begins.
• Yeast removed after about a week – by
filtering.
• Beer bottled for distribution and sale.
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Industrial production of Beer
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Use of immobilised yeast
Yeast cells are immobilised in sodium alginate
beads.
Sugar solution passed down through a
bioreactor of S. cerevisiae containing beads.
Alcohol produced and runs out the bottom of
the column.
Bioreactor can be used continuously – do not
have to stop to separate yeast from alcohol.
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Advantages of immobilised yeast
• Gentle procedure
• Easily recovered
• Reduction in filtration procedure
• Reusable
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Types of Respiration – comparison
Aerobic
Oxygen necessary
Anaerobic
Oxygen not necessary
Produces a lot of energy
Produces very little energy
Occurs in cytosol and
mitochondria
Occurs in cytosol only
Consists of two stages
Consists of one stage only
Produces energy, CO2 and
H2O
Produces energy, ethanol +
CO2 or energy +lactic acid
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Back to slide 15
END
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