Re: Analisi foto lunari 2
Inviato da Paxtibi il 8/1/2007 15:23:27
se il 99% del dna di un uomo qualsiasi č identico a quello di un scimpanzč...
Se č per questo il 30% č uguale a quello della banana, in ogni caso il dato non č proprio corretto e le cose non sono cosė semplici:
Many protein-coding sequences in the genome have been reported to have a 98.5% sequence homology (the percent of DNA that matches between two organisms) for humans and chimpanzees. However, such sequence similarity was based only on a fraction of the total genome of man and chimpanzees, and reflects only the physiological similarities of humans and chimpanzees based on their cellular protein content, not the overall genomic content. The homology frequently reported for the human/chimpanzee genomes excluded "indels," which are areas with zero sequence homology. In a recent analysis by Britten et al., inclusion of "indels" in human and chimpanzee sequences reduced the human/chimpanzee homology to 95%.3 However, preliminary research at ICR using genomic databases and the current literature indicates that the sequence homology between humans and chimpanzees may be less than 90%, as more genomic regions, such as heterochromatin (regions of condensed noncoding DNA) and unresolved alignment gaps are included in homology studies.
(Genomics at ICR)
Ancora:
Cajal-Retzius neurons release a protein called reelin that guides the growth of neurons and the formation of connections among them.
HAR1F was found to be active at the same time as the reelin gene.
Lead researcher Dr David Haussler said: "We don't know what it does and we don't know if it interacts with reelin.
"But the evidence is very suggestive that this gene is important in the development of the cerebral cortex and that's exciting because the human cortex is three times as large as it was in our predecessors.
"Something caused our brains to evolve to be much larger and have more functions than the brains of other mammals."
The analysis showed that HAR1 is essentially the same in all mammals except humans. There were just two differences between the versions found in chickens and chimps.
However, there were 18 differences between the chimp version and the one found in humans - which scientists say is an incredible amount of change to take place in a few million years.
The researchers believe the key gene does not control the production of specific proteins as most genes do, but instead plays a role in modifying the function of other genes.
Professor Chris Ponting, of the University of Oxford, said this suggested that the rapid evolution of the human brain might be due to subtle fine-tuning of genetic function.
His colleague, Dr Gerton Lunter, said: "What is really interesting is that this is a special type of gene.
"It seems likely that it changes the way the brain is wired in some way."
(Research finds 'unique human DNA')
_______________________
Scusate per l'OT ma ci vuole pių prudenza prima di usare certi assiomi con tale sicurezza.
Se č per questo il 30% č uguale a quello della banana, in ogni caso il dato non č proprio corretto e le cose non sono cosė semplici:
Many protein-coding sequences in the genome have been reported to have a 98.5% sequence homology (the percent of DNA that matches between two organisms) for humans and chimpanzees. However, such sequence similarity was based only on a fraction of the total genome of man and chimpanzees, and reflects only the physiological similarities of humans and chimpanzees based on their cellular protein content, not the overall genomic content. The homology frequently reported for the human/chimpanzee genomes excluded "indels," which are areas with zero sequence homology. In a recent analysis by Britten et al., inclusion of "indels" in human and chimpanzee sequences reduced the human/chimpanzee homology to 95%.3 However, preliminary research at ICR using genomic databases and the current literature indicates that the sequence homology between humans and chimpanzees may be less than 90%, as more genomic regions, such as heterochromatin (regions of condensed noncoding DNA) and unresolved alignment gaps are included in homology studies.
(Genomics at ICR)
Ancora:
Cajal-Retzius neurons release a protein called reelin that guides the growth of neurons and the formation of connections among them.
HAR1F was found to be active at the same time as the reelin gene.
Lead researcher Dr David Haussler said: "We don't know what it does and we don't know if it interacts with reelin.
"But the evidence is very suggestive that this gene is important in the development of the cerebral cortex and that's exciting because the human cortex is three times as large as it was in our predecessors.
"Something caused our brains to evolve to be much larger and have more functions than the brains of other mammals."
The analysis showed that HAR1 is essentially the same in all mammals except humans. There were just two differences between the versions found in chickens and chimps.
However, there were 18 differences between the chimp version and the one found in humans - which scientists say is an incredible amount of change to take place in a few million years.
The researchers believe the key gene does not control the production of specific proteins as most genes do, but instead plays a role in modifying the function of other genes.
Professor Chris Ponting, of the University of Oxford, said this suggested that the rapid evolution of the human brain might be due to subtle fine-tuning of genetic function.
His colleague, Dr Gerton Lunter, said: "What is really interesting is that this is a special type of gene.
"It seems likely that it changes the way the brain is wired in some way."
(Research finds 'unique human DNA')
_______________________
Scusate per l'OT ma ci vuole pių prudenza prima di usare certi assiomi con tale sicurezza.
Messaggio orinale: https://old.luogocomune.net/site/newbb/viewtopic.php?forum=13&topic_id=970&post_id=70425