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Change in perspective for Natural Selection
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[QUOTE="BillTre, post: 6288042, member: 581757"] This seems to be an interesting finding: [LIST] [*]that some specific methylation pattern has been maintained millions of years, something that strongly implies a selection to maintain it in the genome for so long. [/LIST] However, the claims that this is the leading edge of a change in perspective on how (or, on what) natural selection operates, seems inappropriate to me. They basically claim that the methylation pattern they found is not a gene so its a new way of considering natural selection. Taking a "gene" as some molecularly well defined entity like a transcription unit makes non-transcriptional molecular feature (methylation in this case) not count as a gene. However, older gene definitions (predating molecular biology) refer simply to an inheritied scorable trait (transcription and translation were unknown). Mapping and genetic tests of inheritance are key to identifying genes by this approach. What the map-able traits are, as long as they were reliably score-able, does not matter. That both molecular and more abstract genetic features can all be put on the same genetic map indicates they are all encoded on the same piece of DNA. This mapping relationship is the basis of how the genes (such as [URL='https://en.wikipedia.org/wiki/HERG']ether-a-go-go[/URL], a fly mutation that causes the flies to shake when they are etherized (common way to reversably knock out flies to look at they and sort them for setting up crosses, thus easy to find mutations), which might not have an obvious basis in genetics were mapped to locations in the genome (along the various DNA molecules). The DNA sequence corresponding tot he map location and its molecular functions were then studied in detail to reveal details of its molecular functioning. A whole series of different molecular functions that can be a changed (resulting in a sore-able phenotype) by changing how the cell's molecular functions, resulting in different phenotypes. There are a huge number of different genetically encoded molecular processes, that can be mutated, to produce a distinct phenotype. Here are some: [LIST] [*]The basic: protein encoding gene, using processes of transcription, translation, possibly followed by processes for proper cellular localization [*]genes transcribing an RNA product: tRNAs, rRNAs, various RNA transcribed sequences that seem to have control functions. [*]DNA binding sites that are based on the DNA sequence. The basis of many described molecular control systems. [*]mutations affecting gene splicing, which can make changes in the protein produced. [*]changes in cell localization. [*]Changes in teleomeres or centromeres that could have big lethal effects in chromosome structure or inheritance or if affecting only a small part of a large repetitive genomic sequence (structure) [*]Sites of genome sequence with as yet unknown functions. [/LIST] [/QUOTE]
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