Two bases join to form the rungs of the DNA ladder. The building blocks which make up all living things. Chromosomes are threadlike structures found in the middle of your cells that contain your genes. Humans have 46 chromosomes in each of their cells. Identical twins are clones that have happened naturally.
Identical twins are clones that have happened naturally.
A code is a system of symbols or letters that represents a message. In DNA the four bases A, G, C and T form a code, telling a cell how to make the proteins it needs. Because of a fault in one of their genes their lungs don't work as well as normal and they may be on a special diet. They are normal children in every other way. One of the 4 bases that makes up the rungs in the DNA ladder.