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Chapter 3

BIO120H1 Chapter Notes - Chapter 3: Endogenous Retrovirus, Distant Relatives, Pseudogene

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Spencer Barrett

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BIO120H1(F) Chapter 3 of Why Evolution is True Monday, September 25, 2017
Orgaiss are palipsests of eolutioary history
Bodies of animals and plants give clues about their ancestry
o Special features like vestigial organs were once useful in an ancestor
i.e., wings of an ostrich
o Atavisms throak traits/gees that re-occur in organisms that have long
been silenced
o Molecular palimpsests genomes of species contain a lot of their evolutionary
o Development from embryos organs and other features appear, change
dramatically, or even disappear completely after birth
o “peies aret perfetly desiged
**Note: Vestigial traits are not functionless, only it no longer performs the same function for
which it evolved
If these traits did happen to be functionless, we would start to see them disappear
**Note: Atavisms and vestigial traits show us that when a trait is no longer used or becomes
redued, the gees that ake it dot istatly disappear fro the geoe evolution really
takes its time to stop their action by inactivating them, and not snipping them out of them**
It is expected that we find these silenced or dead/vestigial genes (which were once
useful but are no longer intact/expressed) in the genomes of species
o Genes were inactivated by mutations, which can continue to occur in the gene
that is no longer expressed and accumulate over time (harmless if they occur in
already-dead genes and passed on)
o Closer relatives share a common ancestor more recently DNA sequences
more similar in close than in distant relatives occurs whether or not a gene is
Endogenous retroviruses those that are able to make copies of their genome and
insert them into the DNA of species they infect
o i.e., HIV
o if infected sperm and eggs, they can be passed on to future generations
Pseudogene a gee that doest futio denoted by the Greek letter Ψ (psi)
o i.e., ΨGLO produces an enzyme called L-gulono-γ-lactone oxidase that is used
to make vitamin C from glucose molecules in non-human species
o human genome contains thousands of viruses nearly all of which have already
been made harmless by mutations
remnants of ancient infections
Almost every species has dead genes that were still active in its relatives and the
common ancestor only killed off in some descendants but not in others this is
evidence for evolution
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