Genes is found in the DNA. It decides a specific characteristic. Genes can transform and take two or more option structures and these structures are called Alleles. Presently allele happens in an altered spot in a chromosome and in people we have two arrangements of chromosomes.
There are 46 chromosomes in the human. 23 from the dad, 23 from the mother = 46 chromosomes.
External factors include physical and chemical signals. Growth factors are proteins that stimulate cell division. – Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.
