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.

Figure 1 A comparison of unicellular and multicellular organisms.

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This is an image of a flow chart. Starting from the top of the image, organisms are divided into two; unicellular (only containing one cell) and multicellular (consisting of many cells). Amoeba, bacteria and paramecium are unicellular organisms. Plants and animals are multicellular organisms.

Figure 1 A comparison of unicellular and multicellular organisms.

Using Figure 1, now complete Activity 1.

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).

Maximise

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).

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Figure 2a is an image of a eurkaryotic cell; labels are drawn to the cell membrane, cytoplasm and nucleus. A scale of 10 micrometres indicates its approximate size. Figure 2b is an image of a prokaryotic cell; labels are drawn to the cell wall, cell membrane, cytosol and DNA. A scale of 1 micrometre indicates its approximate size.

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...

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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Select the answer for

Question 1a

here

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.)

Figure 3 A budding yeast cell-shaped fungus.

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This is an image of a fungus where the scale of 5 micrometres indicates its approximate size.

Figure 3 A budding yeast cell-shaped fungus.

50 × 10^–6 m

5 × 10^–5 m

5 × 10^–6 m

50 cm

5 m

 

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.