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Respiration

The controlled release of energy from glucose, within a cell

- 24 hour process.

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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