linkedin post 2018-05-25 03:55:06

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WHY LINEAR #2. "Even crossing over between one linear and one circular chromosome will yield a linear dicentric that would also be unstable. The advent of sexual crosses may well have driven the advent of the linear chromosome: An ancestral protoeukaryote might have had two circular chromosomes with centromeres; their recombination would have yielded a circular dicentric that, when subjected to incomplete breakage-fusion-reunion cycles, could have given rise to linear chromosomes." https://lnkd.in/ebVhXPf View in LinkedIn
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linkedin post 2018-05-25 03:52:54

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WHY LINEAR #1. "The earliest protoeukaryotes may have had only one or a few linear chromosomes encompassing the entire genome (which also necessitated the evolution of centromeres and telomeres to allow faithful segregation and protect the ends from decay). Linear chromosomes are required because crossing over between two circular chromosomes generates a circular dicentric that is unstable (the chromosome is broken if the two centromeres attach to opposite spindle microtubules)." http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn
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linkedin post 2018-05-23 03:55:31

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GROUP II INTRONS. "They can also spread through the genome by a similar, but less efficient reaction at ectopic sites. The phagocytosis of an α-proteobacterial cell by archaeal (or actinobacterial) eukaryotic precursor could have been accompanied by massive invasion of Group II introns." https://lnkd.in/d8Qr_bk View in LinkedIn
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linkedin post 2018-05-23 03:53:40

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ANCESTRAL RETROTRANSPOSONS. "I propose that mobile Group II self-splicing elements (Group II introns) are a good candidate for the repeats that led to chromosome linearization. Group II introns are the proposed ancestors of introns and non-LTR retrotransposons." https://lnkd.in/d8Qr_bk View in LinkedIn
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