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Flashcards in Origins of life/Astrobiology Deck (14):
1

Use of metagenomics

Analysis of DNA samples to enable cultivation of organisms

2

Examples of multicellularity (5)

Choanoflagellates -> animals
Green algae -> plants
red, brown algae
fungi
Slime moulds, myxobacteria -> fruting bodies

3

Hydrogen hypothesis (4)

Bill Martin
hydrogen-producing bacterium + hydrogen-consuming archaeon
happened before endomembrane evolved
doesn't explain ribosomes

4

Ways to investigate origins of life

biosignatures
biomarkers
sediments
stable isotope fractionation

5

Name a biomarker

Hopanoids (from bacteria)

6

Stable isotope fractionation

changes of isotope abundance ratios
C-13 is fixed over C-12 during photosynthesis

7

Two views on cell

Information-processing
Energy-generating

8

Theories on cells (3)

RNA world
Proto-metabolism
Inorganic cells

9

RNA world (3)

RNA as both genome and catalyst
some ancient RNA-like catalysts have been found
DNA took some roles of RNA later

10

Proto-metabolism (2)

volcanic vents
Iron, hydrogen, sulphur

11

Inorganic cell sources (4)

Spontaneous lipid vesicles
Clay as aperiodic crystals and scaffolding adsorbing amino acids
Nucleotides = ammonium cyanide, urea
Oparin-Haldane hypothesis: organic molecules = UV, lightning + methane and ammonia

12

Panspermia (3)

Arrhenius
Small gap between late heavy bombardment and cellular life
some organic compounds found on meteorites

13

Mars (3)

too cold
pressure too low
plumes of methane = underground microorganisms?

14

Timeline

3,5 bya = prokaryotes
2,5 bya = oxygen accumulates
2,1 bya = eukaryotes
700 mya = multicellularity
420 mya = plants colonise land