B6a: Understanding Microbes

We are used to talking about plants and animals that can be seen and touched. Microscopic organisms such as bacteria, viruses and fungi tend to be either ignored or cause fear. This unit considers the characteristics of these organisms and gives some appreciation of the importance of scale in biology. Practical work with microorganisms develops the skills of working safely and accurately. 

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What is the size of a typical bacterial cell?
A few microns (thousandths of a mm)
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What are the three parts of a flagellate bacillus as shown by E. coli?
Flagellum, Cell Wall and bacterial DNA.
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How can bacteria be classified?
By their shape.
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What can bacteria do in suitable conditions?
Reproduce very rapidly.
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Where can bacteria be grown?
In large fermenters.
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What is yeast?
A fungus.
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what are the four main parts of a yeast cell?
Bud, nucleus, cytoplasm, cell wall.
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How does yeast reproduce?
Asexually - budding.
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Two characteristics of viruses.
They are not living cells, and are much smaller than bacteria and fungi.
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Why do bacteria cells need a flagellum?
for movement
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Why do bacteria cells need DNA?
to control the cell’s activities and replication of the cell.
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Why do bacteria cells need a cell wall?
to maintain shape, and to stop it from bursting
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What are the four main shapes of bacteria?
Spherical, Rod, Spiral and curved rods.
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How do bacteria reproduce?
A type of asexual reproduction - Binary fission
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Describe aseptic techniques for culturing bacteria on an agar plate. (MO = microorganisms)
Petri dishes-nutrient agar jelly&other culture media must be sterilised,the inoculating loops used to transfer MO must be sterilised&the lid of Petri dish's sealed with sticky tape 2 stop MO from the air getting in&contaminating the culture
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What can bacteria survive on?
an enormous range of energy sources.
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What can bacteria exploit?
a very wide range of habitats
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Why can bacteria survive on an enormous range of energy sources and exploit a very wide range of habitats.
because some bacteria can consume organic nutrients and others can make their own.
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What are the consequences of very rapid bacterial reproduction?
They can invade other living things and cause disease and cause food spoilage (make food go off)
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Why do we safe handle bacteria?
Bacteria grow and reproduce more quickly when they are warm, than when they are cold. It would be dangerous to incubate cultures at temperatures close to body temperature (37°C) because doing so might allow the growth of pathogens harmful to health
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What are the safe temperatures for schools and colleges when handling bacteria?
the maximum temperature used in school and college labs is 25°C. However, higher temperatures can be used industrially to produce faster growth.
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What four things does the growth rate of a yeast population depends on?
The availability of food, temperature, pH and removal of waste products.
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Talk about the growth rate of yeast.
The growth rate of yeast doubles for every 10°C rise in temperature. This continues until the optimum temperature - above which the enzymes in yeast become denatured and the growth rate slows.
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Describe two structural properties of viruses.
A protein coat, surrounding a strand of genetic material.
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Where can viruses only reproduce?
in other living cells
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What can viruses only attack?
specific cells.
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What cells might viruses attack?
plant, bacterial or animal cells.
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How does a virus reproduce?
Attaches itself to a specific host cell, injects its genetic material into the cell, uses the cell to make the components of new viruses, causes the host cell to split open to release the viruses.
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What production is yeast useful in?
Food
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Carbon dioxide produced by yeast makes what?
Bread rise
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Ethanol produced by yeast makes what?
Beer and wine.
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Why does the growth rate of a yeast population depend on temperature?
at low temperatures yeast are inactive and at high temperatures their enzymes are denatured
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Give an example of the growth rate of a yeast population being dependant on the availability of food
sugar in wine-making
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Give an example of the growth rate of a yeast population being dependant on the removal of waster products
the ethanol yeast produce in wine-making eventually kills them
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What is the common cold caused by?
viruses which attack cells in the respiratory system.
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Other cards in this set

Card 2

Front

What are the three parts of a flagellate bacillus as shown by E. coli?

Back

Flagellum, Cell Wall and bacterial DNA.

Card 3

Front

How can bacteria be classified?

Back

Preview of the front of card 3

Card 4

Front

What can bacteria do in suitable conditions?

Back

Preview of the front of card 4

Card 5

Front

Where can bacteria be grown?

Back

Preview of the front of card 5
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