How do we inherit phenotypes from parents?

DNA is the key that we inherit from our parent. The functional part of DNA is called gene. Gene is usually composed of two alleles, one from each parent. There are millions of genes in every human cell. There are also some plants and bacteria that adopt asexual reproduction. They are usually growing much faster but less resilient to environment change. In this introduction site, we will primarily focus on sexual reproduction and their genetic evolution.