Where does DNA come from?

Question

And if DNA can change, what did it look like in the first place?

Serious answers only, please.

Thanks

Answer 1

There is a theory called the RNA world hypothesis which suggests that RNA was the first genetic material.

This is backed up by the occurance of naturally occuring so-called 'ribozymes', which are sequences of RNA which can peform catalytic functions, such as cleavage and ligation of other RNA.

RNA is not very stable, but if you remove an oxygen (OH->H) you get DNA which is much more stable.

So, the theory suggests that DNA came from RNA and was more stable so survived longer and thus DNA became the molecule which carries genetic information for long periods of time.

Where DNA or RNA came from in the beginning is not known.

Doesn't really answer your question, but is a related intresting point.

Answer 2

The short answer is that DNA comes from other DNA.

DNA is a self-replicating molecule. It can unzip into two halves and the each half can assemble the missing half out of the chemicals surrounding it in the cell.

The reason that DNA can change is that errors can happen during the duplication process (usually due to radiation, mutagenic chemicals, or heat). A change in DNA is referred to as a mutation.

Okay, that covers how it changes. Your other question is "what did it look like in the first place?". That's an excellent question and scientists are still debating the answer.

The theory that currently has the most support in the scientific community is that DNA (deoxy-ribonucleic acid) was derived from the less stable RNA (ribonucleic acid). So now the question becomes "where did RNA come from?".

You can find tons of information about the different types of RNA here: http://en.wikipedia.org/wiki/rna. But I think that what you are interested in is the RNA World Hypothesis which is described here: http://en.wikipedia.org/wiki/RNA_world_hypothesis

I hope this information is helpful. Excellent question!

Answer 3

DNA comes from your parents. Everyone's looks different (except for identical twins). It can mutate for different reasons.