Question

Fertilization-A mutation in the DNA that encodes the sea urchin protein Bindin changes the shape (conformation) of its extracellular domain. Predict what effect this mutation would have on sea urchin fertilization. Explain your reasoning.

Oogenesis in mammals- Which gamete, a sperm or an ovum, would you expect to have a higher concentration/density (not raw number) of mitochondria, and why?

Answer 1

1. Bindin is membrane protein expressed on the surface of sperm cells. i.e. It is a adhesive protein component of the acrosomal granule in the sperm cell. It is required for the species-specific recognition of the egg cell by sperm. It binds to the glycoprotein receptor on the egg cell surface.

If there is mutation in the Bindin protein that abolishes the activity of its extracellular binding domain, it may abrogate species-specific recognition or abolish the fertilization process.

2. Mitochondria number would be more in the egg cell. However, the egg cell is comparatively larger in size (It is the largest cell in the human body).
The mitochondrial density would be more in the sperm cell (Number is less but size is small as compared to the egg cell)