Practice question

Egg jelly is thick gelatinous extracellular mucoid coat outside vitelline envelope composed of sulfated fucan polysaccharides intermingled with small peptides such as resact and speract. Its principal biological functions include long-range sperm chemoattraction and preparation for fusion. Diffusible peptides establish chemotactic gradient guiding motile sperm toward egg, while polysaccharides interact with sperm receptors inducing Ca2+-dependent acrosomal reaction ensuring membrane fusogen bindin becomes exposed precisely before reaching vitelline membrane. Although it contributes to species filtering, core specificity arises later at bindin-receptor binding step. It does not block polyspermy nor supply metabolic nutrition; polyspermy prevented by electrical shift and fertilization envelope.