What IS a genome exactly?

Okay - this is more of a straight question that an invitation to a debate, though perhaps it has legs; I don't know. I'm sure the answer's out there and relatively easy to get hold of, but I'm simply having no luck because I don't know where to look.I was just reading in a recent New Scientist about the possibility that the neanderthal genome might soon be sequenced. This sounds very exciting, but it got me wondering again about something I really don't understand when it comes to genome sequencing, namely:What does it mean to have a sequenced genome? Especially when it might be that this information might be derived from only a couple of specimens, as in the neanderthal investigation. They are only going to have the genetic sequence from an individual, or at best, a tiny selection of the total neanderthal population.Is the genome the genes that are shared by all individuals of a population at any one time? If so, and if every individual is host to a handful of mutations, how do you know what genes are shared by all by looking only at a couple?Also, it presumably wouldn't be possible to reconstruct a creature from a "genome blueprint" because it hasn't got all the genetic information because it is missing some of the random stuff unique to individuals.Alternatively, when we say we have the chimp genome, do we simply have a few snapshots from different chimps? This would mean that I don't "agree" with the human genome, because I wasn't a part of the sample from which they deduced the human genome (not as far as I know, anyway).If anyone can put me straight I'd be grateful.As for topic destination, I thought there was a question forum, but there doesn't seem to be. I guess this would be Miscelanious then? But whereever you think is best really.ABE - I should note that I have read what wikipedia has to say, for example - but it doesn't seem to directly address my point.(ABE - though it comes closest in the Genomes and Genetic Variation section)Edited by Tusko, : No reason given.Edited by Tusko, : No reason given.

Thread moved here from the Proposed New Topics forum.

No, a genome is an individual thing. One person can have their own genome sequenced. Projects such as the human genome project do take DNA from a number of individuals to account for some variation but they by no means account for all of it. Certainly the sequencing done by Celera Genomics was mostly based on Craig Ventner's own genetic sequence.Any one person's or small sample's average genome is never going to be representative of the whole population. The genes will be shared in the vast majority but not necessarily the alleles. Recent research from the Human Genome project related Haplotype Mapping project (HAPMAP) has shown that there are also variations in gene number in some regions of the genome.What is required to capture the spectrum of genetic variability across a larger population are databases containing both single nucleotide polymorphisms and copy number variation data mapped onto a baseline genome based on the most prevalent variants. Well it might be possible to construct an organism but an 'average' genome might not be a genetic clone of any particular individual. That is relatively irrelevant however since even a 100% identical genetic clone will accumulate epigentic variation leading to differences in the resulting individuals.TTFN,WK

Hi Tusko. If you feel like a long read to get some background in how they do it and what information can be drawn from these types of things, you might want to check John Hawks' FAQ on the subject

Okay - thanks very much for your response. That helps clarify things.Whimsically now... Really powerful computers could lead to the ultimate Dungeons and Dragons experience as you roll your stats - your complete genome stats - and then see them expressed onscreen in your character. How cool would that be?

This looks really helpful, thanks very much!

You know, some of the most exciting evolutionary research is coming out of microarray studies where we're looking at gene expression patterns rather than allelic diversity. One of the problems with looking at gene sequences is that they evolve so darn fast - and so darn neutrally. Gene expression patterns, however, are probably more biologically relevant even than SNPs (!) and it is the evolution of expression patterns which is going to make the headlines in the future, I would guess. Certainly with regard to primate diversification.anyway, that's my 2c.Mick

But the non-stochastic elements which control gene regulation are themselves all genetic, or perhaps epigenetic, so there can be no study of the evolution of gene expression which isn't essentially a study of genetic evolution.Most of evo-devo is the study of changes in gene expression and the resultant changes in morphology, that is simply the result of the strong molecular homology in so many key developmental systems.It seems strange to say that regulation expression patterns are more relevant than SNPs or CNVRs when almost any change in expression pattern is likely to have a basis in some such genetic change.TTFN,WK

This is a guess (most of my posts are) so please feel free to correct this:
A genome is a set of genes. Since all taxonomic groupings are entirely arbitary, so are genomic groupings, but at least we know they relate to a grouping - even if it is arbitary. e.g. my genome is all the genes that sort me from other life forms, and the human genome is the genes all humans posess(ed) that are/were not posessed by "non-humans". Such a species-specific genome is the gene set that permits fertile reproduction between two individuals posessing it, but since there is no chronological start or end point for an individual species, a genome is relative to some fixed point in evolutionary time (eg the species that includes me), and is a temporary state of affairs. There is therefore a primate genome and a citrus fruit genome. Presumeably there are also family and ethnic genomes. These could become species genomes if isolated for long enough. Sorry to not really answer the question but I have no actual knowledge of it, and reply only because I find it a fascinating subject.All the best

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Human Evolution in 42 Steps