Download Microorganisms Microorganisms (microbes) are small living

Microorganisms
Microorganisms (microbes) are small living organisms which can are unicellular
(have only one cell). Microorganisms are found in a great many places- in our
bodies, on our skin, in our homes, and almost everywhere else! Although some
microbes cause harm or disease, many more are completely harmless, and some
are very useful!
Two types of microorganisms are bacteria and fungi.
Bacteria:
Bacteria are single celled organisms. They do not have a proper nucleus. They
appear as shiny dots when grown on a Petri dish in the lab.
They grow in 3 main shapes:
o round (cocci)
o rod - shaped (bacillus)
o spiral - shaped (spirillum)
Bacteria can be grown on special jelly called agar which
provides food for the bacteria. Each circle, or colony, on the
agar plate grew from 1 bacterial cell which has multiplied many
times.
Fungi:
Fungi are organisms that cannot make their own food. They feed on other living
or dead organisms. Fungi often look furry when grown on a Petri dish in the lab.
There are 2 types of fungi:
o moulds
o yeasts
Microbes have a range of conditions in which they work best. They have an
optimum pH, temperature, moisture level etc. In less than optimal conditions,
the enzymes in the cell do not carry out their function as efficiently.
This prevents or slows down the ability of the microbe to grow and reproduce.
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Remember, not all living organisms require the same resources. Some
microorganisms live (and thrive!) in conditions that humans as a species would
find unbearable.
Humans can also use microorganisms in industry. When a living organism is used
in an industrial process we call this biotechnology.
Microbes are most useful for these process becausethey are small and easily manageable,
they reproduce quickly,
they have a small genome which can be easily manipulated,
they can withstand conditions which are unsuitable for many other organisms
(i.e. high temperatures, little or no oxygen etc)
how do we use bacterial cells?
Yoghurt- Yoghurt is a food produced from milk. It is changed by yoghurtforming bacteria.
During the yoghurt production process, the bacteria change the sugar in the
milk into lactic acid. This acid makes the milk thicken and clot, and gives it a
slightly bitter or sour taste.
Other bacteria which make food spoil cannot grow in these acidic conditions,
and so changing milk into yoghurt is a natural way of preserving it. The lactic
acid is described as a natural preservative.
When bacteria is added to milk, it can either be from a pure bacterial culture or
a starter culture of yoghurt (yoghurt which still has live bacteria in it such as
live or bio yoghurt).
Cheese- Cheese is made using milk, rennet and bacteria.
 Bacteria are added to pasteurised milk to convert the sugar into lactic
acid.
 Rennet is added to clot (thicken) the milk.
 Curds form from clotted protein, which separates from the liquid whey.
 The whey is removed.
 The curds are chopped up, mixed with salt (to stop bacterial growth) and
packed and left to mature.
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Rennet contains the enzyme RENNIN which clots the proteins in the milk to
form the curds.
Rennet is produced in 3 ways:
1. traditionally it is extracted from the stomach of calves.
2. more recently it has been produced from fungi.
3. or it can be produced using genetically engineered bacteria or yeast.
how do we use fungal cells?
Baking- For thousands of years humans have been using yeast to make bread.
This yeast is a single-celled fungus. When it respires it gives out CARBON
DIOXIDE.
This is a gas which makes bread rise.
Brewing- Yeast may also produce alcohol when they respire. This means that
yeast can also be used to make alcoholic drinks such as wine and beer.
Beer is an alcoholic drink made from:

WATER

BARLEY

SUGAR

HOPS

YEAST
The yeast uses the sugar in the barley (and the added sugar) to produce carbon
dioxide and alcohol.
sugar
yeast

carbon dioxide + alcohol
The carbon dioxide makes the beer fizzy.
The yeast is above the arrow because it is not used up in the reaction. This
means it can be reused!
When producing wine, the yeast use the sugar from the grapes.
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microbes and renewable fuels:
Biogas is a renewable fuel made using methane gas produced from waste
materials by bacteria. It is used to produce electricity.
Gasohol is another use for the alcohol produced by yeast. It is used as a fuel
for vehicles.
Microbes and breaking down waste:
Sewage treatment- In treatment works the main process is the breakdown of
the waste by the action of decay micro-organisms (bacteria) to make products
that are harmless to the environment.
The micro-organisms need lots of oxygen to work efficiently- this is
accomplished by stirring the waste, or by spraying jets of compressed air.
Sewage contains lots of types of waste. Different types of micro-organism
feed on different waste. This means that a range of different micro-organisms
must be present if all the waste is to be broken down.
Bioremediation- Some microbes are capable of digesting other chemicals, which
we would consider 'harmful' or 'toxic'. Humans have now begun using this to our
advantage. Areas of land which are polluted or contaminated with chemicals
may be able to be restored to their natural state (or as close as possible) by
using bacteria in the soil which can digest the chemicals.
This process is called BIOREMEDIATION.
How do we control the growth of microbes?
Although microorganisms are unicellular, many types of microbe form colonies.
Growth is when the number of cells in the colony increases.
Antibiotics: Antibiotics are chemicals (often made by fungi) that kill bacterial
cells. A doctor may give you antibiotics in the form of a pill. They only affect
bacterial cells.
Detergents / Disinfectants: Detergents are chemicals that help remove dirt,
grime and oils (things that may have microbes in them).
Disinfectants are chemicals designed to remove microbes (particularly
bacteria). While some are better than others, they will never remove all the
microbes.
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Genetic engineering
Growth and reproduction in bacteria is controlled by their chromosomal
material.
Bacterium
Chromosome
Plasmid
A plasmid is a small circle of extra DNA
Genetic engineering involves taking a piece of chromosome containing a gene
from one organism (e.g. human) and transferring it to another (e.g. the plasmid
of a bacteria).
The piece of chromosome inserted into the bacteria allows it to produce a new
substance as it grows.
Because bacteria can grow very rapidly, genetically engineered bacteria can
produce large quantities of a desired substance very quickly.
Below are some chemicals that can be made by genetic engineering and their
uses:
Product of genetic engineering
Application of gene product
Insulin
Used by diabetics
Human growth hormone
Prevents reduced growth and dwarfism
Antibiotics
Used against bacterial diseases
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The process of genetic
engineering
There are several steps in genetic
engineering:
1. Chromosome is extracted and
the required gene is identified
1.
2.
3.
2. The gene is cut out using special
enzymes
4.
3. Remove plasmid from bacterial
cell and cut using the same
enzyme
4. Insert gene into plasmid
5.
5. Insert plasmid into bacterial
‘host’ cell
6. The bacterial cell will grow and
multiply and identical plasmids
will be formed containing the
required gene
6.
7. Product will be produced in large
quantities
7.
The need for insulin
Insulin is a substance produced in the pancreas and which controls the level of
glucose in the blood. Diabetics are unable to make insulin and so have to inject
it. Insulin is now made by genetically engineered bacteria and can be produced
in large quantities.
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The demand for insulin produced by biotechnology is likely to continually
increase because:
1. The only other source is pig or cattle insulin which has the disadvantages:


It is not identical to human insulin and some people may be allergic to
it
Only small quantities can be obtained from animals
2. As people get older Diabetes often develops. Therefore as human’s life
expectancy increases the number of Diabetes suffers will also increase.
Stem cell (covered in investigation and next unit more)
Stem cells in animals are undifferentiated/ unspecialised cells. They can divide
and have the potential to become different types of cell. Stem cells are
involved in growth and repair.
Check point C
Level 4 E&O
I have taken part in practical activities which involved the use of enzymes and
microorganisms to develop my understanding of and their use in industry (also in
subtopic b)
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Properties of microorganism and use in industry
Properties of microorganisms include rapid growth, diverse use of food and wide range
of products. Examples of some cell work and are used in industrial processes.
Yeast in baking and brewing. Bacteria for yogurt and biofuels production. Production of
cheese.
Therapeutic uses of cells
Insulin and other protein production by genetic engineering. Other examples may include
other products of genetic engineering, stem cell technology or using cells to grow
artificial organs.
Controversial Biological procedure
Investigate or debate any relevant topic e.g. stem cells gene therapy, pharming,
transgenic animals and plants
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