Monday, March 22, 2021

life's original enemy: UV radiation

ultraviolet (UV) radiation is the original enemy of life. 

earth was formed ~4.5 billion years ago (bya) and rapidly cooled to allow creation of the oceans just 100 million years later. spontaneous organic chemistry, protocells and early single-celled life all evolved likely surprisingly soon after the appearance of oceans.

early life was fragile molecules and microstructures or proteins and nucleic acids that could easily be blasted apart by UV radiation. the sun has been there the WHOLE time, we take for granted that it's always had damaging effects on life. 

UV radiation smashes into structures like a bullet, so life developed strategies like

  • build barriers to shield oneself
  • build enzymes and other tools that could repair the damage
perhaps this is why "repair" is one of the earliest cellular functions that evolved. using tools like ribozymes (RNA fragments that act as enzymes) or protein-composed enzymes (eg., DNA ligase), both of which are ancient structures. one of life's initial goals was "repair molecular damage", implying life had a natural tendency to want to control chemical reactions. 

https://pubmed.ncbi.nlm.nih.gov/16464022/


@40:10:


-

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)

ancient human

 humans have been doing mostly the same thing for SO many years. talking to each other, schools, trade, crafting, law, society. cultural mod...

  • stories
    why do humans have such a tendency towards creating stories? "A literary cycle is a group of stories focused on common figures, often (...
  • geology and geochemistry
    Geology is the chemistry when traditional 'solids' instead intertwine and act as/are liquids instead. Simple chemistry nonetheless. ...
  • why can't plants walk?
    early in the evolution of life, multicellular organisms climbed out of the oceans and became the first organisms to colonize dry land. early...