Living FactoriesLiving Factories

Unit 7 - BiotechnologyUnit 7 - Biotechnology

Saccharomyces cerevisiaeSaccharomyces cerevisiae

YEAST!!!

YeastYeast

Single celled Single celled microorganismmicroorganism

Type of fungusType of fungus Exist on all living Exist on all living

mattermatter 16 chromosomes16 chromosomes Hundreds of Hundreds of

different species!different species!

Did you know?Did you know?

We may not look much like yeast or We may not look much like yeast or they like us, but many of the 6,000 they like us, but many of the 6,000 genes in yeast have counterparts in genes in yeast have counterparts in humans!humans!

Looking at YeastLooking at Yeast

Yeast as a Living Yeast as a Living OrganismOrganism

As a living organism, just like us, yeast As a living organism, just like us, yeast needs the following to survive and flourish:needs the following to survive and flourish:

-sugars-sugars

-water-water

-warmth-warmth

Respiration is the process by which a living Respiration is the process by which a living organism releases energy from its foodorganism releases energy from its food

Do you remember the Do you remember the difference between aerobic difference between aerobic and anaerobic respiration?and anaerobic respiration?

Aerobic RespirationAerobic Respiration

Humans produce energy through Humans produce energy through aerobic respirationaerobic respiration

In aerobic respiration glucose reacts In aerobic respiration glucose reacts with oxygen in the mitochondria of with oxygen in the mitochondria of the cells to release energy. the cells to release energy.

Carbon dioxide and water are by-Carbon dioxide and water are by-products of the reaction. products of the reaction.

Aerobic RespirationAerobic Respiration

Glucose + oxygenGlucose + oxygen carbon dioxide carbon dioxide

+ water + water + energy+ energy

Anaerobic RespirationAnaerobic Respiration

Anaerobic respiration occurs when Anaerobic respiration occurs when oxygen is not available. oxygen is not available.

In anaerobic respiration the glucose In anaerobic respiration the glucose is only partially broken down, and is only partially broken down, and lactic acid is producedlactic acid is produced

FermentationFermentation

Living yeast cells in the absence of Living yeast cells in the absence of oxygen are still able to use sugar as oxygen are still able to use sugar as their source of food to make energytheir source of food to make energy

This is known as fermentationThis is known as fermentation

In this case ethanol (alcohol) is In this case ethanol (alcohol) is produced instead of lactic acid produced instead of lactic acid

Anaerobic RespirationAnaerobic Respiration(Fermentation)(Fermentation)

Glucose Glucose carbon dioxide carbon dioxide

+ ethanol+ ethanol+ energy+ energy

Aerobic Vs. Anaerobic Aerobic Vs. Anaerobic RespirationRespiration

AerobicAerobic

-oxygen always required-oxygen always required

-efficient method of respiration-efficient method of respiration

-sugar completely broken down to -sugar completely broken down to carbon dioxide and watercarbon dioxide and water

Aerobic Vs. Anaerobic Aerobic Vs. Anaerobic RespirationRespiration

AnaerobicAnaerobic

-oxygen never required-oxygen never required

-inefficient method of respiration-inefficient method of respiration

-releases a small amount of energy-releases a small amount of energy

-much of the energy remains locked -much of the energy remains locked up in the molecules of the end up in the molecules of the end product (e.g. the alcohol)product (e.g. the alcohol)

Quick QuizQuick Quiz

Can you sort out the following statements into aerobic or anaerobic respiration?Can you sort out the following statements into aerobic or anaerobic respiration?

Just fill them into your table!Just fill them into your table!

Glucose + oxygen carbon dioxide + water + energy

Glucose carbon dioxide + ethanol+ energy

Oxygen never required

Oxygen always required

Inefficient method of respiration

Efficient method of respiration

Sugar completely broken down to carbon dioxide and water

Only releases a small amount of energy

Glucose reacts in the mitochondra of cellsMuch of the

energy remains locked up in the molecules of the end product

BreadmakinBreadmakingg

Bread Basics!Bread Basics! Bakers use two simple facts of life to create Bakers use two simple facts of life to create

soft, spongy, moist bread: soft, spongy, moist bread:

1.1. First, they use the fact that yeast (a single-cell First, they use the fact that yeast (a single-cell fungi) will eat sugar: fungi) will eat sugar: -from the sugar yeast creates alcohol and -from the sugar yeast creates alcohol and carbon dioxide gas as waste products carbon dioxide gas as waste products -the carbon dioxide gas created by yeast is -the carbon dioxide gas created by yeast is what gives bread its airy texture, and what gives bread its airy texture, and -the alcohol, which burns off during baking, -the alcohol, which burns off during baking, leaves behind an important component of leaves behind an important component of bread's flavor. bread's flavor.

Bread Basics!Bread Basics!

2.2. Second, wheat flour, if mixed with water Second, wheat flour, if mixed with water and kneaded, becomes very elastic. and kneaded, becomes very elastic.

-the flour-and-water mixture in bread -the flour-and-water mixture in bread becomes stretchy like a balloon because becomes stretchy like a balloon because of a protein in wheat known as gluten of a protein in wheat known as gluten

-gluten gives bread dough the ability to -gluten gives bread dough the ability to capture the carbon dioxide produced by capture the carbon dioxide produced by yeast in tiny flour balloons. yeast in tiny flour balloons.

GlutenGluten

http://www.exploratorium.edu/http://www.exploratorium.edu/cooking/bread/bread_science.htmlcooking/bread/bread_science.html

How to make bread….How to make bread….

You will need:You will need:

1.1. Flour with added salt Flour with added salt and lard rubbed in to and lard rubbed in to make doughmake dough

2.2. Yeast added to warm Yeast added to warm sugar solution and sugar solution and allowed to grow to allowed to grow to produce bubblesproduce bubbles

3.3. Mix the yeast and the Mix the yeast and the flour together in a flour together in a bowlbowl

4.4. Kneading the doughKneading the dough

5.5. Leaving the mixture to Leaving the mixture to riserise

Mixture left in warm place covered by damp cloth

6.6. Proving the doughProving the dough

Yeast releases COYeast releases CO2 2 bubbles making dough risebubbles making dough rise

7.7. Baking breadBaking bread

After dough rises a couple of hours in a warm place, it's After dough rises a couple of hours in a warm place, it's ready to go into the oven. ready to go into the oven.

There, heat causes pockets of gas in the dough to expand There, heat causes pockets of gas in the dough to expand

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