Chapter 47, Problem 47.1CR

What cell-surface event would likely fail if a sperm contacted an egg of another species?

Summary Introduction

To identify: The cell-surface event that has failed in case a sperm contacts an egg of different species.

Introduction:

The process of binding of a sperm to a receptor on the egg surface is species specific. There are many events that lead to the fusion of plasma membranes of egg and sperm.

1. 1. The sperm contacts the jelly coat of egg.
2. 2. The release of enzymes from the acrosomes.
3. 3. Fusion of the sperm and egg plasma membrane.
4. 4. Release of cortical granules and formation of fertilization envelope.
5. 5. Entry of the sperm nucleus.

Explanation of Solution

There are some cell specific surface proteins that is essential for the fusion of sperm and egg. These protein are necessary for the proper recognition. If the gametes are from different species it is not possible for the sperm to induce the acrosome reaction. It is not possible for the sperm to burn its way through the egg’s outer layer.

Conclusion

All the reactions of the fertilization is possible only if the sperm and egg are from the same species. It would not occur if the sperm and egg are from different species.