Question

Read the given statements regarding the contribution of sperm and egg to the zygote and select the correct option.

Statement 1: A defect in the mitochondrial DNA of the sperm middle piece will be transmitted to the developing zygote
Statement 2: Sperm contributes to most of the mitochondria in the zygote
Statement 3: Egg contributes to most of the cytoplasm
Statement 4: Both sperm and egg contribute haploid nucleus

Answer 1

Fertilization is the process of fusion of male and female gamete that results in the formation of a unicellular zygote. The acrosome of the sperm contains corona penetrating enzymes, zona lysins and acrosin which dissolves the different layers of the egg and results in penetrating the ovum. The egg is larger compared to the sperm and it contributes its cytoplasm during fertilization.

The middle piece of sperm is packed with 50-70 pieces of mitochondria. It provides energy and strength to the sperm for locomotion. Mitochondria contain their own genome i.e mitochondrial DNA. But in zygote formation, only the head portion containing a haploid set of chromosome (male pronucleus) enters the ovum. The rest of the structures like the middle piece and tail of the sperm remains outside the ovum. Both the gamete (egg and sperm) contribute one haploid nucleus and which results in a diploid zygote.