Paris japonica, a relative of Trillium that can't count (probably should have been named Quadrillium), has over 150 billion base pairs in its genome in comparison, humans have about 3 billion base pairs, so the genome of this little woodland wild flower is 50 times bigger than ours. In case you’ve forgotten your freshman biology, genes are composes of a sequence of 4 nucleotide bases, adenine, thymine, guanine, and cytosine, and taken three bases at a time they spell out the genetic coding for each of the 20 amino acids that compose our proteins. It isn’t clear how or why an organism should have such a large genome, although hybridization and chromosome doubling is a common mechanism of speciation among plants, but even with over 1200 chromosomes, the adder’s tongue fern doesn’t have a genome any where near that huge. However, organisms with big genomes seem to be at greater risk of extinction, again for uncertain reasons; perhaps they may be unable to deal with changing conditions because they have so many copies of each gene, which would be like tossing a thousand coins versus two coins. In the latter case they come up HH or TT 25% of the time, but with a large number of coins the ratio of H:T will always be close to 50:50 and never even close to all heads or tails.
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1 week ago in Genomics, Medicine, and Pseudoscience
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