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Author Topic: How do we know how many genes are in a Genome?  (Read 3393 times)

Offline vj_tu

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How do we know how many genes are in a Genome?
« on: 30/12/2005 14:39:26 »
How can we determine the numbers of genes in which an individual species possess?
Why scientists have recently claimed that human genome is more likely to be less than 40,000 genes as previously predicted?
What experimental evidence brought them with the suggestion of fewer human genes existence??
« Last Edit: 20/06/2008 14:26:40 by BenV »


 

Offline chris

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How do we know how many genes are in a Genome?
« Reply #1 on: 18/07/2008 10:44:08 »
The human genome project read the entire DNA code from end to end. This sequence was added to a database in a form that computers can read. Genes are revealed by the presence of certain "give away" sequences such as promoters that activate gene expression, and polyadenylation signals that help transcribed genes to exit the nucleus.

By scrutinising the sequence in this way scientists can predict the minimum number of genes that must be present in the genome. The real number may be more because there may be genes hiding inside other genes and even inside the junk (intron) sequences inside genes. There may also be cryptic (hidden) genes that use unusual promoter and enhancer elements that could be missed at first glance.

Consequently the numbers are an estimate, although it's still humbling to think that there are more genes required to power a rice plant than a human. We can retain some pride, however, in the fact that fruit flies have on 13,000 genes!

Chris
 

blakestyger

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How do we know how many genes are in a Genome?
« Reply #2 on: 18/07/2008 13:13:26 »
That's right - when the human genome was first sequenced there were some long faces when it turned out not be be as big as expected from such a 'complex animal' as ourselves!

My dog has a bigger genome than I have. [:-[]
 

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How do we know how many genes are in a Genome?
« Reply #2 on: 18/07/2008 13:13:26 »

 

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