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Microgravity: living on the International Space Station
Microgravity: living on the International Space Station

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1 Microbes, bacteria and fungi

This week, you will look at microbes, bacteria and fungi. What are they? And are they the same thing?

The term ‘microbes’ describes microorganisms. These exist either as single cells (unicellular) or as a colony of cells (multicellular), as shown in Figure 1.

An image of a flow chart showing comparison of unicellular and multicellular organisms.
Figure 1 A comparison of unicellular and multicellular organisms.

Using Figure 1, now complete Activity 1.

Activity 1 Unicellular and multicellular organisms

Timing: Allow approximately 15 minutes

Choose the correct options to complete the following statements.

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You have now looked at bacteria, but what about fungi? The first difference to consider is that fungi are eukaryotes while bacteria are prokaryotes (Figures 2 a and b respectively).

Described image
Figure 2 (a) A eukaryotic cell where the scale is 10 micrometres (10 × 10–6 m) and (b) a prokaryotic cell where the scale is 1 micrometre (1.0 × 10–6 m).

Using Figure 2, now complete Activity 2.

Activity 2 Eukaryotic and prokaryotic cells

Timing: Allow approximately 15 minutes

Choose the correct options to complete the following statements.

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5. What is the scale of the sketch of a yeast fungus in Figure 3?

(Hint: this scale includes the Greek lower-case letter mu, μ. This means multiply the distance by 0.000001.)

An image of a budding yeast cell-shaped fungus.
Figure 3 A budding yeast cell-shaped fungus.

a. 

50 × 10–6 m


b. 

5 × 10–5 m


c. 

5 × 10–6 m


d. 

50 cm


e. 

5 m


The correct answer is c.

In summary, fungi:

  • are unicellular eukaryotes
  • are about 10 micrometres big
  • contain a cell membrane, cytoplasm and a nucleus.

and bacteria:

  • are unicellular prokaryotes
  • are about 2 micrometres big
  • contain a cell wall, cell membrane, cytosol and DNA.

You will now revisit your bread mold experiment to see how you got on.