Genome complexity: Smallest gene count for life (Introduction)

by David Turell @, Friday, March 25, 2016, 14:59 (1274 days ago) @ David Turell

More comments are turning up about this study. Mycoplasma are the smallest-sized genome bacteria known to science:

"The team's starting point was the bacterium Mycoplasma genitalium, which has the smallest known genome of any living cell with just 525 genes. However, it also has a very slow growth rate, making it difficult to work with. To practice synthesizing genomes and building new organisms, the team therefore turned to M. genitalium's cousins, M. mycoides and M. capricolum, which have bigger genomes and faster growth rates. In 2010, Venter's team successfully synthesized a version of the M. mycoides genome (JCVI-syn1.0) and placed it into the cell of a M. capricolum that had had its own genome removed. This was the first cell to contain a fully synthetic genome capable of supporting replicative life.


"Ultimately the team removed 428 genes from the JCVI-syn1.0 genome to create JCVI-syn3.0 with 473 genes (438 protein-coding genes and 35 RNA genes)—considerably fewer than the 525 genes of M. genitalium. Interestingly, the functions of around one-third of the genes (149) remain unknown. “I was surprised it was that high,” said Hood, “but I also think we kid ourselves about how much we know about the genomes of organisms. There's still an enormous amount of dark matter.'”

Comment: There are two approaches to studying origin of life, bottom up or top down. Bottom up, starting with inorganic Earth has been a total failure so far. Top down is this attempt to see what a minimum set of genes might be. Very large:

" Let's see now. 473 genes having 531kb. In other words this minimal organism has over 500,000 base pairs. This means that the search space for this relatively simple lifeform is 2^500,000!"

From this ID website:

Comment: The above quote assumes looking from bottom up and searching for just the right combination of genome bases to make the organism when starting from scratch. What top down does is point out how difficult it is to find any way to imagine a bottom up natural beginning to life, yet we live. A good reason to look at a supernatural source.

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