The Origin of Species

Question 1

Deep sea (“Lost city”)

Answer 1

• Hydrothermal vents: chemical circulation, leading to biochemistry and the formation of bacteria
• Energy from proton gradients in water

Question 2

RNA as the origins of life

Answer 2

RNA are enzymes, which can form proteins, and eventually, DNA (protected in lipid vesicles)

Question 3

The Fermi Paradox

Answer 3

lack of evidence for extraterrestrial life, conflicting with high estimates for their existence (are we alone?)

Question 4

How recent did humans come into existence, compared to the age of the universe?

Answer 4

We arose less than a billion years ago (~200,000 years), whereas the universe is 14 billion years old.

Question 5

The great oxidation event

Answer 5

• Roughly 2 billion years ago: sudden increase in atmospheric oxygen, leading to the death of many anaerobic/methane-producing organisms
• Only recently reached 100%, making Earth more habitable for today’s species (explosion of life)

Question 6

Eukaryogenesis

Answer 6

• Eukaryotes: nucleus, mitochondria, sex, phagocytosis
• Eukaryogenesis occurred ONCE, 2 bil. years ago (not from natural selection)
• Archaebacterium engulfed a heterotrphic eubacterium, forming mitochondria, which led to the formation of eukaryotic cells

Question 7

Ediacaran Biota and the Cambrian Explosion

Answer 7

• Ediacaran Biota: early evidence of multicellular organisms
• Cambrian Explosion: most major animal groups appear in the fossil record
  WHY?
• Changes in oxygen, geography, trace metals -> exoskeleton formation, more predation -> selection pressure

Question 8

Benefits of DNA vs. RNA -> LUCA

Answer 8

• More stable, resistant to sunlight
• More information could be stored (double helix also provides for the ability to check for mistakes)
• DNA replication is quicker
• Last Universal Common Ancestor (LUCA) was a single cell DNA protein organism -> archaea and bacteria formed, but no other new life