Question

Discuss the human life cycle including the process of mitosis and meiosis

Answer 1

A human's life cycle starts with meiosis producing gametes and a consequent development due to mitosis. Human cells have 46 chromosomes, of which 23 are per parent. These comprise only half of the 46 chromosomes when gametes are made. They are produced in the ovaries' female and male reproductive organs and the testes, respectively in the form of eggs and sperm. When a sperm and an egg participate in fertilization, it produces a zygote. The zygote undergoes extensive mitotic division to form a hollow ball of small cells that after the sixth day of fertilization implants itself into the mother's uterus. It forms three layers after this: the mesoderm, the endoderm and the ectoderm, which later evolve into structures such as the nervous and circulatory system. The mother will give birth to the baby after the stages of dilation and expulsion, after nine months of growth. Brain and body grow quickly during infancy. A puberty, males can produce fertile sperm and females can produce monthly eggs since gametes are produced by meiosis. Human beings are at the height of their fertile years during their 20s, but after age 30 people start aging significantly. Hormone levels drop, skin becomes thinner, gray hair and wrinkles appear, brain cells start dying, and so on. Beginning around the age of 35, humans will lose one hundred thousand brain cells a day. Humans have regions that bind chromosomes, called telomeres. A telomere is a sequence of repeated nucleotides which protects the chromosome from losing DNA. Nevertheless, a part of the telomere is absent as cells divide and the telomeres shorten as humans mature. This is thought to cause death as pieces of DNA are lost without telomeres to rely on after cell division.