If there are only 4 nucleotide types in DNA why are all living things so different?

Answer 1

The pairs of nitrogen bases form a kind of digital code and their order is what contains genetic "information". Since the strands of DNA are very long, millions of pairs long actually, they can encode a wide variety of proteins (which is the main function of DNA, AFAIK) which leads to diversity. Imagine 100 MB of data: it could be 200 vacation photos, a music video, a small game or a Beethoven symphony, while it's made up of 1s and 0s.

Answer 2

A single human has 23 chromosome pairs. Even the smallest chromosome contains over 50 million base pairs! More importantly, single segments that contain important DNA are often thousands of nucleotides long. A language made up of 4 letters has many words if those words are thousands of letters long.

Answer 3

Over eons of evolutionary history, nature decided that four nucleotides provides the right balance between species variability and excessive redundancy. Scientists believe this is the reason why DNA has evolved to contain four nucleotide base.

Biology tends to be conservative in the literal sense, in the Occam's Razor sense. Occam's principle is the simplest answer is usual the correct one. In biologic systems, the simplest solution is usually conserved over time.

Clearly, we know now that a binary system is necessary and sufficient for encoding, storing and transmitting information. But there are four not two nucleotides.

I have surmised that the reason for four nucleotides is to have a reliably reproducible code. A pair of code units is identical when reversed in duo, i.e. a plus-minus tandem paired with a minus-plus tandem contains identical information when reversed. Supposedly the basic unit of genetic information is the codon, which is a sequence of three nucleotides. Combinations of three are needed to prevent automatic reversible identity. Obviously you can still have anagram codons, but three is the minimum necessary to avoid reversible identity.

And we need that fourth nucleotide to allow for the minimum number of matched pairs, given the need for three. Reproducibility requires the paired helices to make fresh templates for the additional copies.

Answer 4

Despite being comprised of only four nucleotide bases, there are millions if not more pairings in DNA. The entire strand of DNA is divided into sections and each section accounts for a certain trait/function. So while one person's genome might be AAAAAAAAAAA, another's might be AAAAAAAAAAG and the variation continues. On the chance that two people both have the same pairing for a particular section, other sections will be different. And since there are millions of other sections as well, the chance that all the sections being the same for two different individuals is minuscule.

Answer 5

The sequence and arrangement of these nucleotides in the DNA determine the genetic instructions that code for specific traits and characteristics in living organisms. The variations in these genetic instructions lead to the diversity seen in living things. Additionally, differences in gene regulation, gene expression, and environmental factors also contribute to the vast diversity among living organisms.

Answer 6

That is because the combination of those four are so complicated. That is because there are so many combinations of those 4 nitrogen bases.