Cell recognition and the immune system

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Question 13
Medium
a.

When a phagocyte engulfs a bacterial cell, a vesicle called a phagosome is formed inside the cell. Describe how the engulfed bacterium is then destroyed by the phagocyte.

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b.

Phagocytes contain actin filaments and myosin motor proteins. Myosin molecules can attach to lysosomes and transport them towards the phagosome, as shown in Figure 1.

Lysosome transport in a phagocyte. Figure 1 shows a phagosome enclosing a bacterium on the right. An actin filament is represented as a thick diagonal line. A lysosome, depicted as a spherical organelle containing enzymes, is attached to a myosin molecule. The myosin molecule has two globular heads bound to the actin filament and a tail anchored to the lysosome. An arrow indicates the direction of movement of the lysosome along the actin filament towards the phagosome.

Use your knowledge of how myosin and actin interact to suggest how the myosin molecule moves the lysosome towards the phagosome. Do not include the roles of calcium ions or tropomyosin in your answer.

[2]
c.

This movement of lysosomes happens rapidly after a phagosome is formed. Suggest and explain one advantage of lysosomes moving towards the phagosome.

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Cell recognition and the immune system Questions

  1. A Level
  2. /Biology
  3. /Cell recognition and the immune system