Inherited change

Genetic information is transmitted from generation to generation to maintain the continuity of life. In sexual reproduction, meiosis introduces genetic variation so that offsprings resemble their parents but are not identical to them. Genetic crosses reveal how some features are inherited. The phenotype of organisms is determined partly by the genes they have inherited and partly by the effect of the environment. Genes determine how organisms develop and gene control in bacteria gives us a glimpse of this process in action.

Homologous Chromosomes

Homologous chromosomes are pairs of chromosomes in a diploid cell that have the same structure and the same genes, but not necessarily the same varients of those genes

• There are 22 matching pairs of homologous chromosomes. Each pair is given a number and in the original zygote, one of each pair came from the mother, and one from the father.
• The non-matching X and Y chromosomes are sex chromosomes, which determine the sex of the individual. All other chromosomes are called autosomes. The Y chromosome has portions missing and is therefore smaller than the X chromosome
• The pairs of chromosomes can be distinguished not only by size and shape, but because each pair has a distinctive banding pattern…