Once the sea urchin sperm has chemotaxed to an egg of the sa…

Once the sea urchin sperm has chemotaxed to an egg of the same species to fertilize it, there are additional steps that involve species specificity. Identify two such such steps, and for each, 1) briefly describe the biological role for the step (i.e. what happens when it occurs) and 2) identify the molecules and describe their locations. (Do not use chemotaxis).