We have even less genes than we thought

<P>It’s just a new genescan computer algorithm being applied. Bioinformatacists are constantly tweaking the computer programs that scan the genome sequence and try to predict all the protein-encoding genes. At the release of the draft sequence, the estimate was ~30,000. Then it went up to 40,000, then 50,000, then back to 30,000, now down to 20,000. There are some people that seem to think that this new estimate of 20,000 genes is more accurate because the genome sequence is now quite “polished” (as we geneticists say). But I wouldn’t bet on it. We are not going to know the true number until we have hands-on experimentally verified them all, and that’s going to take a long looooooong time.<P>
 
I think it is rather interesting from a social viewpoint. We used to think that we are so complicated compared to other animals that we gave ourselves a huge number of genes (i think it used to be 100.000 even). Then it has been slowly going downhill until we are now at the same level as a fruitfly.

I guess the human genome project put back the modesty in the word human.
 
i think it's a fern that has the most genes, some crazy no. like 3 000 000, not sure on that one though. Anyone know how much work there is out there for bioinformaticists? What kind of work is it?
 
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Avatar said:
so, what's so good in having many genes anyways?
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Well, it's not good or bad. An organism has as many genes as it has.

It’s just that this low gene count -- practically the same as the nematode worm <I>C.elegans</I> (19,000 genes) -- poses a significant biological problem. How do we account for the vast differences between a worm, a fruitfly (~15,000 genes) and a human given that we all have roughly the same number of genes? This used to be explained away by saying the humans have ~100,000 genes. It's an exciting time to be a geneticist! :D
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My Sexy Blue Feet said:
Anyone know how much work there is out there for bioinformaticists?
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A lot! This is just the beginning of the genomics and proteomics age.

What kind of work is it?
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It's mostly "dry biology" (ie. computer crunching). From what I have seen, bioinformaticists do little "wet biology", although many have come from an experimental background. I imagine that you would need such a background in order to fully understand what you are modeling on your computer.<P>
 
So we are not as complex as we once thought.

We are still too complex to understand each other.
 
we've never known how complex we are and how much for the complexity goes to genes
I, for one, have never thought that we are some wonder of creation. Quazi-intelligent animals.
 
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alty said:
So we are not as complex as we once thought.
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We are extremely complex phenotypically. It turns out, however, that we are not nearly as complex genotypically as we thought. So, as I said above, the challenge is to find out how such a complex animal as ourselves can have so (relatively) few genes.<P>
 
Hercules Rockefeller said:
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We are extremely complex phenotypically. It turns out, however, that we are not nearly as complex genotypically as we thought. So, as I said above, the challenge is to find out how such a complex animal as ourselves can have so (relatively) few genes.<P>
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Maybe, as opposed to a fern, human genes carry more information and a lot more value per gene...

totally stupid guess I am making.
 
i think fern genes have alot more "junk" DNA in them than we do. But then, when they actually do figure out what the hell junk DNA does, that'lll give us some more meaning to the answer
 
sargentlard said:
Maybe, as opposed to a fern, human genes carry more information and a lot more value per gene...
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It’s not that our genes carry more information; it’s to do with what happens to the proteins that our genes produce. It’s the proteins that do the actual work in our cells and physically make us what we are.

‘Genome’ = all the genes that are present in the cells of an organism

‘Proteome’ = all the proteins that are present in the cells of an organism

The HGP has demonstrated that the human genome has only marginally more genes than flies and worms. So the human genome is not that much more complicated than flies and worms, but our proteome is considerably more complicated, and that’s where the difference in complexity between humans and invertebrates lies. A human has an order of magnitude more types of protein than a worm or fly.

There is considerably more alternative splicing of genes in human cells than in invertebrate cells. Alternative splicing is where different combinations of exons are left in the mature mRNA after splicing, resulting in proteins that differ in their primary amino acid sequence. Thus, in contrast to the “one gene, one protein” dogma, one gene can give rise to multiple variations of the same protein. Furthermore, mammals have many more gene families than invertebrates. In other words, invertebrates tend to have only a single copy of each gene whereas most of the excess genes (compared to worms/flies) that do exist in the human genome represent family members – ie. related genes that all produce proteins with a related, but different, function. This greatly increases the biological subtlety and complexity of protein-protein interactions that are possible from a relatively small number of excess genes. So maybe you can begin to see that looking at genes alone is not sufficient when tackling the subject of relative organism complexity. The proteome is an equally important consideration.
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In addition, more genes also means more variability in metabolic pathways. Many "primitive" organisms like fungi or prokaryotes have a vaster metabolic variability than e.g. mammals and of course need to possess the additional genes coding for the respective enzymes.
BTW just for nitpicking: I'd define proteome as the collection of a all proteins in a given cell type under a defined condition. This is because in contrast to the genome the can be very variable in different cells or under different conditions (same goes for the transkriptome and metabolome).
 
CharonZ said:
BTW just for nitpicking: I'd define proteome as the collection of a all proteins in a given cell type under a defined condition.
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Oh, I agree completely. Cell type is all-important. On a very basic level I was trying to address the concept of overall organism complexity and whole-organism differences, so I was crudely defining "proteome" as all proteins that make up an organism for that purpose.

I realized as I did so that biochemists would be rolling their eyes. :)
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I am a biologist I usually do roll eyes on many biochemistry people though ;)

(OK don't hit me, I only do so cause I give genetics courses for biochemistry (graduate) students) ;P
 
Yes, as of August 31st, 2005, the Federal Genome Instute says that we have about 25,000 genes and they were quite surprised that it is now lower than previous estimates of up to 40,000.
 
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