Origins of life Flashcards
how old is the earth and how do we know
4.6 billion years old and by examining the decay of uranium into lead
what is earths current atmosphere categorized as
an oxidizing atmosphere
what is the Oparin-Haldane hypothesis
that the macromolecules making up all life must have been produced vis abiotic synthesis from a reducing atmosphere
what the Miller-Uray experiment proved
that the formation of life-critical molecules started as an abiotic process (the Oparin-Haldane hypothesis)
what did the Miller-Uray experiment show
that the lack of O2 means that energetic ultraviolet lights and lighting provided energy needed to form more complex and important molecules
what may have acted as an early catalyst for reactions
clay
what 3 things are needed for life
mechanisms to store info, energy transfer to enable work, and compartmentalization to keep work local and enhance reactions
what is a ribozyme
strand of RNA that can act as a catalyst
how is RNA critical for the control of gene expression
removal of introns form newly synthesized RNA, cleaving mRNA to cause them to beak apart, RNA nucleotide order defines its shape which then defines its function
how was the short sequence of nucleotides making up RNA formed and why is it useful
through abiotic synthesis which is useful for catalyzing reactions and editing itself, along with storing information that could be copied
how was DNA formed
RNA started as self-replicating and catalyzed the formation of small proteins which then made DNA simpler to use/make
are ribozymes of enzymes more efficient and why
enzymes because they can become more specialized (10-100 times faster than a ribozyme)
why is DNA better (3)
extremely stable, double strand provides an extra copy of the correct info, double strand allows for error checking and repair
what is the citric acid cycle
it is a key component to cellular respiration in creating complex molecules
how does the citric acid cycle work
electrons released during oxidation used later in the respiratory pathways to generate ATP, which can be used to synthesis precursor molecules (the building blocks for amino and fatty acids)
what were the first cell membranes made of
inorganic materials (not lipids)
often NiS or FeS
purpose of the first cell membranes not being lipid
segmentation of H+ ion concentrations to do work
allow for natural phosphorylation of ADP to ATP
what is phylogeny
the evolutionary history of organisms demonstrated using trees
how can we determine where the tree splits
by seeing differences in the ribosome/RNA sequence
the more differences in the rRNA the more distant the species are related
how many domains were originally thought to be in the tree of life
3, bacteria, archaea, and eukarya
how many domains are there thought to be now in the tree of life
2, bacteria and archaea
(eukarya thought to have branched from archaea)
what is LUCA
last universal common ancestor
how did we determine traits of LUCA
examining common proteins across all domains
what traits did LUCA have (6)
- anerobic
- fixed CO2 into organic molecules
- uses the reverse citric acid cycle
- uses H2 as a source of hydrogen
- converted nitrogen to ammonia
- lived in a hot environment
