Can DNA be manually coded?

Question

I know we can splice genes together but do we have the technology to build genes from scratch using the base amino acids?

Sorry, yes I mean nucleotides/nucleobases, not amino acids... *blush*

Answer 1

Genes are not made from amino acids, but from nucleotides.
Yes, it is possible to synthesize a given sequence of nucleotides. This is done using automated systems and there are many companies that will provide you with a sample of specified DNA (for a hefty price)

Answer 2

As you have already been told it is possible to synthesize sort lengths of DNA usually between 17 and 75 nucleotides long, which is quite cheap around 50p per nucleotide. Any more than this length tends to be unreliable in the sequences as mistakes can occur. A gene is a very long sequence of DNA, the length of the sequence can differ depending on the origin of the gene. Or in your terms what organism the gene is intended to be created for. For bacteria as little as 2kb would be sufficient, however for eukaryotic this could be much larger, the largest known human gene being dystrophin at 2.4 million bases. As I have said the synthetic DNA molecules are limited in size and therefore unable to be large another to carry a complete sequence for a gene. But you said that you know how genes are spliced together during a genetic modification experiment. Well what would stop us from joining individual synthetic DNA molecules together to produce a longer sequences that technology does exist in the form of ligases and restriction endonucleases, but we may not even have to use the latter.


We could make the synthetic DNA molecules so they contained compatible sticky ends at each end of the molecules. We could also make the opposite end incompatible which would allow us to control orientation of the DNA molecules. In doing this we could make it impossible for the molecule to fit together in any other way. Therefore these molecules could only join in one orientation. If it was done in separate stages for example, the fist two are joined and the product separated and then joined to the third and so on to create an ever extending molecule; using DNA ligase to covalently bond them. It would be a long and tedious job but I would say it is possible. However we lack the understanding of protein structure and it is very difficult to look as the amino acid composition of a protein and deduce it function. Therefore although we could create a DNA code and therefore a protein it is unlikely that we could produce a synthetic functional protein or in other words a gene. But that is not to say this will not be possible in the future.

hope this helps in your understanding.

Answer 3

It is possible to make the polio virus from scratch: Syntheis the nucleotide sequence, put it into a medium containing the capsid monomers, and they spontaneously form around the DNA. Neat eh?

Answer 4

Pieran is right, you can synthesize DNA "from scratch", and it's actually pretty cheap these days. However, it's technically difficult to make long DNA strands, and it's pretty much impossible to make an entire gene. At least I haven't heard of it.

Answer 5

its too complicated and so far no one has been able to do that (not that we want to though)