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3 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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1
Respiration
The controlled release of energy from glucose, within a cell
- 24 hour process.
2
Contents
Aerobic respirationStage 1Stage 2Anaerobic respirationAerobic – BiochemistryAerobic Vs Anaerobic
Industrial FermentationYoghurt ManufactureBeer ManufactureUse 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 ATP).
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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 RespirationThe 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
ORWaste 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 Co-enzyme 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
See slide 27 for solution
Complete this yourself – a minimum of four points
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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
Micro-organism used
Desired product
Brewing
Baking
Yoghurt makingCheese making
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Completed tableOriginal
foodMicro-
organism usedDesired product
Brewing Starch, sugar yeast Alcohol
Baking Starch yeast Carbon dioxide
Yoghurt making Milk Bacteria Lactic acid
Cheese making Milk Bacteria e.g. Danish
blue
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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 added to increase starch supply.
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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 – comparisonAerobic
Oxygen necessary
Produces a lot of energy
Occurs in cytosol and mitochondria
Consists of two stages
Produces energy, CO2 and H2O
AnaerobicOxygen not necessary
Produces very little energy
Occurs in cytosol only
Consists of one stage only
Produces energy, ethanol + CO2 or energy +lactic acid
Back to slide 15
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END