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CONFINED. "There is also evidence that recombination at meiosis is largely confined to structural genes or adjacent DNA." https://lnkd.in/dx9WaSq View in LinkedIn

EPIGENETICS. "Evidence is now available which strongly indicates that the control of gene activity in higher organisms depends in part on the pattern of cytosine methylation in DNA, and that this pattern is inherited through the activity of a maintenance methylase. Epigenetic defects may arise by the loss of methyl groups which the methylase is unable to replace in somatic and also germ line cells, if de novo methylation cannot occur." https://lnkd.in/dx9WaSq View in LinkedIn

BIOLOGICAL FUNCTIONS OF MEIOSIS #4. "Fourth, that it helps maintain the immortality of the germ line, possible by a process of rejuvenation involving the removal of faulty RNA and protein molecules, or by the elimination of defective meiocytes." https://lnkd.in/dx9WaSq View in LinkedIn

BIOLOGICAL FUNCTIONS OF MEIOSIS #3. "Third, that it is essential, at least in animals, for the reprogramming of gametes which give rise to the fertilized egg." https://lnkd.in/dx9WaSq View in LinkedIn

BIOLOGICAL FUNCTIONS OF MEIOSIS #2. "Second, that recombination at meiosis plays an important role in the repair of genetic defects in germ line cells." https://lnkd.in/dx9WaSq View in LinkedIn

BIOLOGICAL FUNCTIONS OF MEIOSIS #1. "Four possible biological functions of meiosis are considered. First, the conventional view that it generates by recombination and sexual reproduction the genetic diversity on which natural selection can act." https://lnkd.in/dx9WaSq View in LinkedIn

REPEAT CIRCLE INVASION. "I propose that linear chromosomes arose as the consequence of the invasion of a circular genome with repeat sequences." https://lnkd.in/d8Qr_bk View in LinkedIn

WHY MEIOSIS? “We regard meiosis as accomplishing four functions: (1) reducing ploidy (parasexuality also accomplishes this, albeit less efficiently); (2) purging deleterious alleles and unmasking advantageous recessives when meiotic products are haploid (parasexuality also does this); (3) reducing ploidy while also generating complete chromosome sets rather than incomplete or chaotic sets (the elegance of meiosis I); and (4) generating recombinant offspring via independent assortment and crossing over in heterozygotes.” http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

EXCEPTIONS. "This argument ignores systems like the bacterial XerD/C resolution machinery, which efficiently cuts dimeric circular chromosomes at specific dif sites. A similar system could have been used to resolve dimeric circles in the meiosis of early eukaryotes." https://lnkd.in/d8Qr_bk View in LinkedIn

SO ENDS this curated glimpse into gene life cycles. Pseudogenes, retrogenes, chimeric genes, gene recruitment and modification, gene silencing, and vertical gene transfer can occur at florid rates: there is nothing static in the world of genes. New metabolic pathways, new gene regulatory systems and genetic rewiring all occur continuously on biological timeframes, and all appear to be subject to, and shaped by, the great hand of natural selection by selective survival. View in LinkedIn