How is it possible that over 20 million living organisms on the planet are made up of only 5types of nucleotide bases arranged in long chains

The nucleotide bases are adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U). The bases combine with sugar to make them adenosine, guanosine, cytidine, thymidine, and uridine repectively.

The bases can be arranged in many different combinations and the genes in their long chains can have trillions of different combinations.

scientists have discovered that hiv does not cause aids by the virus's direct effect on the host's immune cells, but rather through the cells' lethal influence on one another. researchers from the gladstone institutes have revealed that hiv does not cause aids by the virus's

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.