Distinguish between the two processes of cell reproduction.

Question

What will be an ideal response?

Answer 1

Most cells in the human body reproduce through a process known as mitosis in which DNA replicates itself, permitting the duplication of chromosomes, and ultimately the formation of new cells with identical genetic material. In the first stage of mitosis, the rungs of the ladder-shaped DNA split, opening like a zipper. Then each half of the DNA molecule regenerates and replaces its missing parts, forming two distinct cells. It is this process that enables humans to develop from a single fertilized egg into a child, adolescent, and finally, adult. The process of mitosis accounts for the replication of all body cells.
The second process-meiosis-the reproduction of gametes (sex cells), occurs in two stages. First, the 46 chromosomes begin to replicate as in mitosis, duplicating themselves. But before the cell completes dividing, a critical process called crossing-over takes place. Chromosome pairs align and DNA segments cross over, moving from one member of the pair to the other. Crossing-over creates unique combinations of genes. The cell then divides into two cells, each with 46 chromosomes. As the new cells replicate, they create cells containing only 23 single, unpaired chromosomes. The resulting gametes each have only one chromosome from each pair (that is, one each from the male and female). This permits the joining of sperm and ovum at fertilization to produce a fertilized egg, or zygote, with 46 chromosomes, forming 23 pairs with half from the biological mother and half from the biological father.