lecture 12- origin of life Flashcards
what are the four main stages to produce simple cells
abiotic synthesis of small organic molecules
joining of monomers into polymers
packaging the polymers into protobions
origin of self replicating molecules that would make inheritance possible
what is thought to have been the atmosphere of the earth originally
a reducing atmosphere
what is a reducing atmosphere
thick with water vapour, nitrogen and its oxides, carbon dioxide, methane, ammonia, hydrogen and hydrogen sulphide
who made the primitive soup hypothesis
oparin and haldane
what is the primitive soup hypothesis
that the earth was mostly water before and contained all the building blocks necessary for the creation of organic chemicals
what do you need to create organic chemicals from simple molecules
no free oxygen (all in the water)
source of energy
chemical building blocks
time
who tested the primitive soup hypothesis
miller and urey
the atmosphere became full of oxygen when it used to be mostly carbon, what happened
carbon was used for photosynthesis and oxygen was released
how are polymers made and what is it called
by dripping monomers onto hot sand, clay or rock
dehydration synthesis or condensation reaction
what is a protobiont
a pre cell
what are the characteristics of a protobiont
have membrane
perform homeostasis
simple reproduction
metabolism
what is the first type of nucleic acid used in cells
RNA
why was RNA first used in cells or pre cells
it acts as an enzyme
can reproduce
more flexible than DNA
why do we have DNA now instead of RNA
dna is more stable
less easy to break down (bacteria can have enzymes that break down rna)
what is the order of evolution of prokaryotes
bacteria came first then archae then eukaryotes
what is the oldest known fossil and what is it made of
stromatolites
made of layers of bacteria and sediment
do prokaryotes have cell walls
yes
what replaced protobionts
chemoheterotrophs
why did chemoheterotrophs evolve first
because photosynthesis is a more complex process
what caused the evolution of autotrophs
the limited supply of organic molecules
what happened when photosynthetic organisms started releasing oxygen
oxygen is a radical molecule that is dangerous for bacteria that cannot handle it
it wiped out the majority of the population of bacteria
oxygen revolution
when did the oxygen revolution happen
2.4 billion years ago
which domain can be all four combinations of chemo/photo and hetero/auto
eubacteria
how did eukaryotes evolve
from symbioses and genetic exchanges between prokaryotes
