Topic 6- Origins of Life Flashcards
you usually can’t date fossils themselves, just the ___ above and below where they’re found
strata
Eventually, C14 becomes ______
- what does it turn into?
undetectable
it turns into Nitrogen 14 (so at C14’s half life, 50% of it has turned into N14)
_____ _____are the sites of earthquakes and volcanoes
tectonic boundaries
____ provide the first evidence for continental drift because..
fossils.
same genus of fossil plant found in australia, antartica, and south america provides evidence for palaeo-continent Gondwana (on big continent which later separated b/c of continental drift)`
solar system originated about ____ billion years ago
4.6
how many mass extinctions have occurred?
5
________ look identical to living mats of microbes and could explain when life began
stromatolites
explain the 4 steps of origin of life on earth
- abiotic synthesis of organic molecules
- abiotic synthesis of macromolecules
- formation of protocells
4 self- replicating molecules
* 3 & 4 can be in any order
explain the process of step 1 of the beginning of life on earth
(abiotic synthesis of organic molecules)
inorganic atmospheric gases (no O2!) –> energy (lightning, UV, asteroids, deep sea hypothermal vent) causes abiotic synthesis –> organic molecules (amino acids, nitrogenous bases, sugars, lipids)
explain step 2 of the beginning of life on earth
( abiotic synthesis of macromolecules)
amino acids, nitrogenous bases, sugars –> proteins, enzymes, nucleic acids
- RNA monomers produced spontaneously from simple molecules
how did the abiotic “stew” lead to the formation of RNA?
abiotic stew of inorganic matter –> simple organic molecules –> RNA nucleotides –> RNA able to replicate itself, synthesize proteins, and function in info storage
Explain the formation of protocells
- life reproduces : DNA molecules carry genetic information and life requires energy (metabolism)
- needs to separate from the environment, so a cell membrane forms (provides a concentrated environment)
vesicles form faster in the presence of a type of ___ ____
volcanic clay
thought to be very common 4 bil yrs ago
what are protocells
spontaneous formation of hollow lipid vesicles suggest how early cell-like structures may have arisen (bi-layered structure similar to living cell membrane)
- sphere would have been able to keep or export own products (confining organic molecules increases rate if reactions)
explain step 4 (first nucleic acids)
- first genetic material (RNA):
1) single stranded, fragile, self replicating
2) can catalyze rxns (ribosomes)
3) favored by NS (“RNA World”)
4) evolved and potentially became double stranded DNA - DNA (genetic material of all living organisms today)
1) double helix = very stable structure
2) more accurately replicated and also favored by n.s.
