Lecture 1 - How did life on earth arise Flashcards
(35 cards)
Vitalism
Religious theory, pre scientific
Example/ argument for vitalism
Urea unique to living organisms and can be made form basic chemicals - when something unique to humans its seen as God
Darwins theory
large body of water of chemicals randomly reacted to form life
Oparin - haldene discovered whihc theory
Primodial soup theory
Original Urey miller experiment + observations
set up flasks of water, hydrogen, ammonium + methane w/ spark - pretend lighteninig
after a day = colourless to pink
after a week = pink to red = amino acids present
Orgel, crick, cech experiment - why it didnt work + improvement
try to prove DNA was starting point
DNA couldn’t of survived in the harsh conditions
Could of been RNA instead
RNA theory - why ppl thought it wouldn’t work first + development
Though RNA had no enzymes but found Ribozyme which means RNA self replicating and can pass on its genetic info
Why rna wouldnt work + development
difficult to make - base and nucleotide might not stick during early earth instead PNA = peptide nucleotide acid
Characterisitcs of PNA
polyamide backbone instead of sugar
can pair w/ strands DNA, act as enzyme, transfers gentic info and can replicate
How was PNA found
Urey miller repeated experiment with gases actually present on early earth and found PNA
Compartmentalisation
scientists argued dont need genetic info or proteins but membrane important
what did oparin find in primordial soup theory
coacervates= very basic cells - like oil sits on water (insouble) end up reacting + can take in chemicals or split off and grow
Evidence for primordial soup
presemce montmorillonte (clay) + coacervates one earth earth and m catalyses reactin of C
Hypothermal vent/ metabolism theory`
most evidence- lots organisms near vents + life present
v hot + acidic so life prestn but not for long
so forms and then moves to sea
alkaline vents discovered and acidic sea= proton gradient so energy
LUCA
last common ancestor - evidence for vents
look at bacteria work back to common gene- can metabloise hydrogen and use proton gradients
Phylogneetic tree
show how things related
3 groups of life
Bacteria Archea Eurarya
Eukaryote
orgnaism consisting of a cell or cells where fnentic infor in dna un form chromosomes cintained w/in nucleus
Bacteria
member of a large group of unicellular organisms whihc have cell wall but lack organelles +unorganised nucleus - some can cause disease
Archea
microorganism similar to bacteria in size and simplicity of structure but radically diff in molecular organisation
difference between prokaryote and archea
both prokaryote
histone - no histones
both 70s ribosomes but diff shape
sensiitve to antibiotics - not sensitive
examples extremeophile
human gut and most archea
how to prokaryotes replicate
binary fission
Prokaryotes characteristics
linear Dna
membrane bound organelle
no cell wall
cytoskeleton
