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
why is LUCA important even though it wasn’t the first life form
showed what was critical for life (all living organisms today descended from LUCA)
what are the common features shared by all present day organisms (7)
- cells defined by a membrane of bilayer lipids
- genetic system based on DNA
- system of information transfer (DNA-RNA-Proteins)
- ribosomes as the central feature of protein assembly to produce amino acid chains
- reliance on proteins as the major structural and catalytic molecule
- use of ATP as the currency of chemical energy
- common pathways of energy transformation
where did oxygen come from
original photosynthetic organisms that used light to extract hydrogen from hydrogen sulfide which was used to fix CO2 into carbohydrates
why was cyanobacteria important
able to oxidize water (which was more available) allowing for bacteria to thrive
what are stromatolites
layered rock formed when microorganisms bind particles of sediment together forming a thin sheet
found in shallow water
why/how could aerobic respiration evolve
O2 became more available
difference between energy levels of anaerobic and aerobic respiration
aerobic gave 30 ATP molecules per glucose instead of 2
importance of aerobic respiration for the cell
- cells could become larger and more complex with larger genome
- cells could create more specialized proteins and organelles
- specialization of proteins allows for meiosis and mitosis and specialization of cells within an organism
what is the theory of endosymbiosis
thought that chloroplasts and mitochondria are derived from free-living prokaryotic cells
what are mitochondria and chloroplasts descended from
M- aerobic respiration
C- cyanobacteria
what are 6 things that support the theory of endosymbiosis
morphology, reproduction, genetic information, transcription and translation, electron transport, sequence analysis
what does morphology show that supports the theory of endosymbiosis
the shape and size are like that of prokaryotic cells
what does reproduction show that supports the theory of endosymbiosis
they divide by binary fission like prokaryotic cells
what does genetic information show that supports the theory of endosymbiosis
they contain their own DNA with protein coding and non-coding genes essential for organelle function
what does transcription and translation show that proves the theory of endosymbiosis
they contain complete transcription and translation machinery
what does electron transport show that proves the theory of endosymbiosis
they have electron transcription like prokaryotes
what does sequence analysis show that proves the theory of endosymbiosis
shows that these organelles belong on the bacterial branch of the tree of life
what is vertical gene transfer
genetic inheritance form one generation to the next within a species
what is horizontal gene transfer
genetic inheritance between unrelated species
(a change in location but not function, contribution to evolution)
