Question: If we are all mutants then surely there is someone who isn't a muntant for us to be compared to because mutants are not mutants because they are different from other mutants but because they are different from 'normal' people. So are we really all mutants?
Karolina Chocian answered on 6 Jan 2014:
The term mutant has been used loosely in the lectures 🙂
The reason why Alison pointed out we are all mutants is to show the variability of our genes and the way nature has worked to promote diversity. It’s an interesting point, for example looking at the assembled ‘human genome’. What it actually is, is a scientific “collage”. it is not the one ultimate “wild type” individual.
It is a bit easier with worms. There is a “wild type” strain of worm that has been isolated a while ago and has been cultivated ever since. Worms are all the same, they have exactly the same cells in the same places and the gene forms they have are identical. Then, when we are doing experiments, and we have a different worm that (in my case) ages slower- I can tell it has a mutation in particular gene, and therefore it’s a mutant.
This is also one of the reasons why we have to use animals for medical research. Genetic background of laboratory animals allows us to compare results and be sure of our discoveries, while genetic background in humans is extremely varied.
This gets us back to humans, we are all mutants, not because we are different from some kind of ideal “wild type”, we are all mutants because we are all different. We have the same genes at the corresponding chromosomes but in slightly different forms (called alleles of a gene) and that causes for example, different hair colour etc. We can argue about the semantics but that was is not the point. The point was to show how similar and yet wonderfully different our specie is.
I am happy to be a mutant (and actually have genetic testing done to prove it!) and therefore one of a kind, are you?
Andrew Beale answered on 6 Jan 2014:
Karolina has given a really good answer. The one thing I would add is that in some cases there really is such a thing as a ‘default’ specimen for a species. This is especially the case in palaeontology. For example, when scientists discover a skeleton (or part of a skeleton) they use a single example of a species to check what that new discovery is. This single example is called a Holotype (it’s not always a complete skeleton itself!) and the Wikipedia article gives a good in-depth discussion.
Penelope Mason answered on 6 Jan 2014:
I agree with Karolina,s summation, but I started answering before she posted so i’ll post this too in the hope that redundancy of information helps ; )
The basic definition of mutant means different from the norm, and since the word “variant” is often used for differences that aren’t bad, such as extra petals on flowers, “mutant” often carries the idea of a change that is in some way bad or unwanted. (Variant is mostly used for differences that are common such as hair colours.)
The word mutant has been used for a long enough time that it’s meaning hasn’t really kept up with what we know. If you look at the level of the phenotype I.e. how an organism actually looks and functions, we do (usually) have reference non-mutant or ideal forms – for example, the human blueprint has two legs so more or less would be considered a mutation.
However, when you look at genes, because the code used to make proteins (and therefore the body) is redundant, two different code “spellings” may give the exact same functional protein, just as English and American spellings of a word both convey the same meaning and are both “correct”. Here, these differences are just variations and we all have them.
The reference or standard code spelling for any gene is just a convenience as something to measure all the rest against. Usually it comes from the code of the gene the first time it was read. Or it might be the most common spelling. This is just like how in the UK, British spellings are the ideal. Therefore since everyone have some of these variations, and we have lots of genes, we are all mutant compared to some reference spellings, but it doesn’t mean that’s a problem.
When a mutation causes the protein to be less or non-functional, however, the reference code will obviously be the sequence that gives a functional protein, as the mutations don’t give variants that don’t make a difference, but something that IS a problem. Here, it’s like using a jumbled or nonsense word with no meaning left.
John Robert Davis answered on 6 Jan 2014:
All answers have taken the words from my mouth. I would also like to add that variability in genes (mutations) is what allows us to adapt to our environment. Therefore for life to flourish we need mutations!