1-4: Early World + Life Flashcards
Which two organelles (mentioned) is LUCA thought to have possessed?
Cell Membrane and Ribosomes
Which is thought to have been the first to play a role in storing biological information - DNA, RNA, Proteins or Carbohydrates?
RNA
What did the Urey-Miller experiment demonstrate?
That the complex organic molecules required for life could have been spontaneously created in the conditions present on the early earth.
What is the name of the theory that Peter Mitchell proposed regarding energy and early life?
The Chemiosmotic Theory
What is the basic principle of the chemiosmotic theory?
Electron transport creates an electrochemical gradient across a membrane, which is used to synthesise ATP as H+ flow through ATPase
What is the name of the protein (and the specific part of it) involved in Archaean photosynthesis?
Bacteriorhodopsin (and retinal)
How is retinal involved in Archaean photosynthesis?
Retinal absorbs light and undergoes cis-trans isomerisation - the unstable cis form reverts back, pushing H+ across a cell membrane
How are Type I and Type II photosystems structurally different?
Type I (One) are modified on the Oxidising side, Type II are modified on the reducing side
Which types of photosystems are found in which types of bacteria?
Green sulphur bacteria - Type I
Green non-sulphur bacteria - Type II
Purple bacteria - Type II
Cyanobacteria - Types I and II
Why was there a delay between the appearance of cyanobacteria and the accumulation of oxygen in the atmosphere?
Initially, oxygen reacted with molecules such as methane (atmosphere) and reduced metal ions (oceans), until these were used up (became oxidised).
What genetic process allowed cyanobacteria to possess both Type I and Type II photosystems?
Lateral Gene Transfer
Describe 2 negative impacts of oxygen on life
It reduced the concentration of metal ions in the ocean (once oxidised, they precipitated and were hard to access)
It formed reactive radicals, making cell membranes leaky and causing DNA mutations
How was oxygen a factor in the first (Huronian) ice age?
It reacted with methane, converting it to carbon dioxide (which is a less potent greenhouse gas), causing a cooling effect.
Describe 2 positive impacts of oxygen on life?
Aerobic Respiration is more efficient, so allowed cells to become bigger
The formation of the ozone layer reduced UV radiation at the earth’s surface, expanding the locations where organisms can live
Which types of cells were (probably) involved in the endosymbiosis event which led to eukaryotes?
A phagocytic archaeon engulfed a purple bacterium (which became the mitochondria)
