Transcript you`ve got to let this fungus work for a couple

Micro-Organisms
Micro-Organisms
Micro-organisms are tiny living organisms.
All living organisms feed, grow and reproduce.
Some micro-organisms can be useful whereas
others can be harmful.
All living organisms have a life cycle to
ensure survival.
Different micro-organisms are found in
different places/habitats.
Key Vocabulary
Bacteria
Bacterium
Bug
Germ
Microbe
Mould
Pasteurize
Sterilise
Virus
Yeast
Micro-organisms are too small to
be seen with the naked eye!
500 bacteria would only cover a full stop!
You would need 160 000 000 000 bacteria
to fill a teaspoon!!
A colony of micro-organisms
Some micro-organisms can be
harmful!
Certain bacteria can make stone
decay…as well as teeth!!!
Clean Those Teeth!
Design a dental
hygiene poster
which gives advice
about how to keep
your teeth and
gums healthy
(4-6 bits of
advice!!).
Micro-Organisms –
The Sequel!!!
Preventing Micro-organisms Spreading
Micro-organisms can spread illnesses
and diseases in a variety of ways
including:
Coughs and sneezes
Touching infected people or objects
Insect bites
Infected food
Stop Them Spreading!!
List as many ways as you can
of preventing the spread of
micro-organisms.
Kitchen Hygiene
It is very important to prevent microbes
spreading in the kitchen because this
could lead to food poisoning!
Food/Personal Hygiene
Task 1: Complete
information text about the
spread of microorganisms
Task 2: Design a Personal
Hygiene poster (A4
paper).
Making Food Using Micro-organisms
Some foods are made using
micro-organisms.
These include…..
Yeast
Yeast is a micro-organism
which is used in the making of
bread!
Technical Vocabulary
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Kneading – pressing and folding the dough with
your hands until it is smooth and stretchy. This
spreads the yeast evenly around the dough and
helps it to rise.
Knocking back – deflating the dough with a
GENTLE punch. This evens out the texture of
the bread.
Proving – this is the correct name for the process of
rising in bread making.
Rising – the time it takes for the dough to increase
in size.
Yeast
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If you’ve ever taken a bite of bread you’ve made,
you may wonder how simple ingredients like flour,
salt and yeast can produce raised, sometimes
wonderfully bubbly bread.
It makes people a little squeamish to know it that
yeast makes bread dough rise because it is a live
single-celled organism.
Specifically it is a variety of fungi called
Saccharomyces cerivisiae, which is harnessed to
eat, drink and be merry, before dying a quick death
when exposed to oven heat.
Yeast
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You can buy several different types of
yeasts on the market.
The first of these is called live or fresh yeast.
This is relatively unstable, requiring
refrigeration, and it has a very short shelf life.
Dried versions, sold in packages or cubes is
essentially cells of Saccharomyces
cerivisiae, which are waiting to be activated.
Yeast
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Like many fungi types, yeasts for bread dough responds to
warm water, which begins to bring the little cells to life.
Then when exposed to sugars in bread and in flour, it
begins to eat, digesting portions of these sugars. This
eating process goes on for a short period of time only.
Eventually the yeast will die within a few hours, especially if
the dough is allowed to grow cold or exposed to too much
air.
Don’t feel too sorry for it when you have a slice of bread, as
its life would be short under any circumstances. At least by
using it for bread or wine, you get to give this fungus a
happy and full life.
Yeast
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It might be embarrassing to the yeast to have to
admit that this rapid eating/digestion cycle makes it
just a trifle gassy.
As Saccharomyces cerivisiae is feasting, it begins
to release gas bubbles of carbon dioxide, and small
amounts of ethanol alcohol. These bubbles,
trapped in the bread dough, cause the rising action
with which we’re familiar.
This is why bread making can be time consuming;
you’ve got to let this fungus work for a couple of
hours in order to sufficiently rise dough.
Yeast
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Once dough has been acted upon by fungi, not all
of the cells are quite dead. Putting the bread in the
oven is relatively macabre, from the standpoint of
the yeast (if it had a point of view).
The heat from the oven makes remaining cells go
into overdrive, madly munching away at the sugars
and expelling carbon dioxide prior to expiring from
the oven heat.
This is why bread continues to rise during its early
cooking stages, and then may deflate slightly as
cooking continues.
Bread Rising
Yeast
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There are a few things that inhibit these microbes
from their natural function. Too much salt can halt
its rising action.
Therefore bread dough recipes usually contain a
little salt and a little sugar for balance.
Fats can also inhibit the fungi, and you’ll note that
breads that have butter in them, especially salted
butter may not have the same rise due to the
butter’s presence.
If we add more sugar I think that….
If we add more yeast I think that…
When the yeast is mixed with sugar
and water, dough is created and
when it is left to ‘prove’ the yeast
reproduces and makes CO2
which makes the dough ‘rise’.
Preserving Food
In order to prevent food ‘going
off’, it can be preserved/stored in
the following ways.
Freezing
Dehydrating
Canning
Pickling
Freezing
Dehydrating
Canning
Pickling
Helpful Micro-organisms
We cannot survive without some
micro-organisms!
Microbes are
essential to life on
earth.
Without any microbes, we would be
left with mountains of waste material
that wouldn’t decay.
What A Lotta Rot!
Average rotting times for some
household waste products are:
Orange peel and banana skin:
2 years!!
Crisp Packet:
20 years!!
Aluminium Drinks Can:
100 years!!
Glass bottle:
1000 000 years!!!
Plastic Bottle:
Possibly never if not
biodegradable!!!
Will it Rot or Not?!
Another word for a material that will rot is…..
BIODEGRADABLE
Draw a dustbin and inside it
draw those items that are not
easily biodegradable.
Outside the bin, draw those
items that are biodegradable.
Mould
When you see
mouldy food,
you are seeing
colonies
(groups) of
microbes.
Investigating Micro-Organisms
Our Challenge:
 Discover the conditions
microbes require to grow
well.
Explain whether the
evidence shows that
microbes are living things.
Mould Investigation Planner
Question
Equipment
Method
We Will Keep Constant
We Will Change
Mould Investigation Findings
Describe what the results of
the investigation show.
What conditions do microorganisms prefer?
How do you know?
Are micro-organisms living
things?
How do you know?
Research Tasks
Compile a factfile on either:
1. Louis Pasteur
2. Anton Van Leewenhoek
3. Alexander Fleming
Write an information text on:
4. Preserving Food
5. Good Microbes!
Helpful Micro-organisms
We cannot survive without some
micro-organisms!
Microbes are
essential to life on
earth.
Without any microbes, we would be
left with mountains of waste material
that wouldn’t decay.
Food/Personal Hygiene
Task 1: Complete a
powerpoint explaining all
about helpful micro –
organisms!