I need help with the following question What is the differen

Solution

Differences in sea urchin and mammal fertilization.

1. Fertilization is external in sea urchin while that in mammals is internal (in uterus).

2. In sea urchin, bindin protein is responsible for sperm-ovum species-specific interaction. Glycoprotein ZP3 and N-actyl glucosamine do this function in mammals.

3. Acrosomal reaction is triggered by jelly coat in sea urchin while contact with zona pellucida starts acrosomal reaction in mammals.

4. Both fast and slow blocks to polyspermy exist in sea urchin. In mammals only slow blocks occur.

5. In sea urchin, the polyspermy blocks occur through Na⁺ based membrane reaction while in mammals this happens through Ca⁺⁺ based membrane wave.

Similarities in sea urchin and mammal fertilization

1. The acrosomal reaction is common in both.

2. The sperm binds to the outer coat of the ovum.

3. The sequence of the sperm-ovum interactions are similar in both.

4. Blocks to polyspermy have similar chemical mechnisms (Na and Ca in sea urchin and mammals, respectively) in both.