DNA - Holographic?

Factual Questions
1

Let me bounce my ignorance off you for a moment.

A lot of what I’ve read about DNA, genetics, cell replication etc (which isn’t a huge amount) seems to be supporting the idea that, instead of ‘DNA is equivalent to programmed instructions’ (in that one bit of DNA/One Gene/Whatever has one job to do), rather it seems as if any particular bit can be responsible for a range of quite diverse functions.

For example, certain coat colour combinations in cats are associated with deafness. (IANAMolecular geneticist, so that might be way off base)

I’m thinking along the lines of neural nets and holograms, where each part is not merely a discrete part, but has many functions within a system.

With a neural net, destroying a few nodes doesn’t rob the system of one particular function and it isn’t possible to point at part of the network and say ‘this is the bit that does X’
With holograms, each point on the image actually contains the whole picture (from a specific angle).

So could DNA.

Can you see where I’m coming from?
Maybe I’m just wrong.
As I said, IANAMolecular geneticist, so please don’t just haul me up on my terminology.
I’m not sure if this is all that new an idea, but I couldn’t find anything by Googling.

2

that was meant to be:

“So could DNA be described as holographic?”

3

It sounds as if you are taking the “blueprint for life” description of the genome too literally. A better, but less flashy, analogy would describe DNA as a “parts list for life”. Even then, DNA can only supply a listing of the protein components. Carbohydrates, lipids, and all sorts of small molecules are unaccounted for by the genome.

4

Well, IANAMolecular geneticist either, but let’s see about this.

First of all, DNA isn’t holographic in the sense that you can’t reproduce the whole from a fraction of it. It can, however, withstand a certain amount of flaws.

Gene mutation is far more common that you might think, and not as dramatic an event as superhero comics would have you believe. At any given moment, your body has thousands of cells with your DNA slightly malformed. Most of the time this isn’t critical, since the flawed area doesn’t relate to the functions of that particular cell. (Sometimes, though, the end result is cancer.)

Mutation in reproductive cells has greater effects, since the mutation will be present in every cell of the resulting individual. Still, in many cases the result is neutral or only slightly harmful. To understand the level of self-correction in DNA, let’s take a look at the operating level of individual genes.

A gene has a single function: it contains the sequence for the synhesis of a single type of protein. Anything more complex, like a tissue of an organ, is the result of numerous genes operating together. A single gene can have a wide-scale effect, however.

Consider what you might call “the gene for brown eyes”. Now, this gene doesn’t contain the information required for a complex system like the eye. It might not even be responsible for synthesizing the brown pigment. All it does is start a genetic chain reaction that leads to the specified color.

It follows from this that a gene might have several, seemingly unrelated effects. In the same way, several genes might have a similar effect, and all could equally well be called “the gene for x”. Thirdly, a missing gene doesn’t necessarily bring the whole system to a halt.

Like a neural net, DNA has a level of redundancy. If a fraction of the information is lost or mutated, the end result is in most cases still a functional organism. This isn’t because the lost information could be replaced, but because a singular gene isn’t critical to the process.

5

Hmmm, maybe, I was thinking about how often we hear announcements like ‘scientists have identified the gene that does X’ - I wonder though if X is all it does, or if it also is involved (perhaps in a lesser capacity) in doing Y and Z.

6

Thanks isani, redundancy and genetic chain reactions probably covers exactly what I was fumbling to express.