1.2 Three Domain of Life Flashcards
What is the origin of life?
Panspermia: Life originated from microorganisms or chemical precursors of life from outer space and were able to initiate life after reaching earth
What is the theory of Chemical Evolution
or Abiotic Synthesis?
The formation of complex organic molecules from simpler inorganic molecules through chemical reactions in oceans during the early history of earth
AKA PROTOCELL
What was primitive earf be lyke?
The primitive earth was hot,
anaerobic with warm oceans
A lot of volcanic activity, meteorites
& radioactivity
What was critical to primitive earf?
Absence of O2
What type of gases existed in primitive earf?
Simple organic molecules formed
from CH4, CO2, H2, N2, NH3 gases
dissolved in the oceans
Building organic molecules requires ________
Electrons
The lack of O2 in the atmosphere of the early earth’s atmosphere favored the synthesis of \_\_\_\_\_\_\_\_ molecules
organic
AKA reduces atmpsophere
Why was the Murchison Meteorite so important?
Discovered amino acids and organic compounds that are similar to ones found in cells
Astrobiology? What it be?
Study of the origin,
evolution, distribution and
future of life in the universe
What is the Cambrian Explosion?
Started 545 mya By 600 mya fossil ancestors of crustaceans, starfish, sponges, mollusks, worms, chordates and algae
Microorganisms existed for
~________ billion years before
multicellular organisms
3.2-3.5
The 1st cells were _______________
marine
prokaryotic anaerobes
Multicellular bodies with
bilateral symmetry were
not present before _____ mya
600
Multicellular organisms
with a body appear in the
fossil record ______ million
years ago
600
What are Stromatolites?
Microbial fossils in
layered sedimentary rock
Just fossils, no living things
When did eukaryotes arise? What was the evidence they were around during that time?
2.3-2.4 bya due to evidence of sterols + cholesterol found on crystals
Photosynthetic bacteria
starting producing oxygen
_____ bya
2.3
How did eukaryotes
come about?
Endosymbiosis: Relationship between two
organisms, in which one is
living inside the other
Engulfed but not digested
Ribosomes are made up of _____
RNA
In fact, all cells have genes of rRNA
rRNA mutates slowly so it is predictable cus it’s so slow
How is the three domain tree of life built?
Based on comparing DNA sequences for the smallest subunit of rRNA genes
What is the Svedberg unit?
a unit describing
sedimentation rate in a centrifuge tube
The small subunit (30S)
of the prokaryotic
ribosome is composed
of ____ RNA
16S
The small subunit (40S)
of the eukaryotic
ribosome is composed
of ___ RNA
18S
What is horizontal gene transfer?
Transfer of genes across species barrier
