Unit 1 Flashcards
when was earth formed?
4.5 BYA
why was earth inhospitable?
hot
no oxygen
water only as vapur
when did the first cellular life appear?
4 bya (end of Hadean)
what is the surface origin theory?
spontaneous arise of membrane-enclosed strucutre from primordial organic-inorganic soup
what is the subsurface origin theory?
interaction between alkaline hot water beneath ocean and cold acidic water
what was the energy supply beneath the ocean?
H2S and H2
what was the energy supply on the surface?
iron
how did metal precipitates form?
interaction between sulfides and iron
how did the first macromolecules form?
metal precipitates catalyzed formation of amino acids. sugars and bases
what is the RNA world theory?
first molecule entrapped in self-replicating system were RNAs
how was the first semipermeable membrane formed?
RNA catalyzed formation of first simple peptides that coated mineral
what is the order of events according to RNA world theory?
- formation of amino acids, nucleotides and sugars
- RNA catalytic world and self-replicating RNA
- synthesis of complex proteins via catalysis
- DNA replaced RNA
- lipid arise and entrapped proteins, RNA and DNA
- LUCA appeared
- divergence of LUCA to Bacteria and Archaea
what evidence was there than B and A branched from LUCA?
structure of lipids in B have ester bond and ether bond in A
how was the first self-replicating organism formed?
after lipoprotein structure entrapped DNA and RNA
when did first methanogenesis develop?
Archaea
3.9 BYA
what developed after methanogenesis?
anoxygenic photosynthesis
who did anoxygenic photosynthesis?
purple and green bacteria
consumed H2S
what developed with anoxygenic bacteria?
H2 oxidizing organisms
who developed after anoxygenic photosynthesis?
cyanobacteria at the end of Archaean
what did Archaean end with?
big oxygenation event led by cyanobacteria
who developed in Proterozoic?
first eukaryote
who developed in phanerozoic?
multicellular eukaryote and early animals
how was banded iron formed?
oxygen and available iron
what kind of iron is in banded iron formations?
ferric
how did earth become oxic?
when all iron exhausted then o2 increased
what did o2 accumulation lead to?
formation of UV shield zone and evolution expanded
how did eukaryotic cell appear?
1) DNA accumulation led to nucleus formation then nucleus containing cell ingested chloroplasts and mitochondria
2) early cell was archaeal and consumed O2. host ingested H2-producing bacteria
what commonality does eukaryotes and bacteria have?
types of lipids
what commonality does eukaryotes and archaea have?
transcription and translation
endosymbiosis
chemoorganotrophic bacterium host ingested O2-consuming and ATP producing bacteria
- facultative aerobic organism ingested chloroplast where O2 was made
what did early autotrophy discover?
Aquifex: hyperthermophile bacteria
what was the first cell?
anaerobic and autotrophic
obtained CO2 and electrons to reduce CO2 and get H2
what is phototrophy?
evolved in B
used solar radiation
what is the common ancestor for all bacteria?
chloroflexus (anaerobic phototrophs) except Aquifex and Thermotoga
what are the 4 evidences to support endosymbiosis?
- both mito and chloroplasts contain ribosomes that are prokaryotic 70S and have 16S r RNA same as prokaryotes
- same antibiotics that affect ribosomal function in Bacteria inhibit ribosomal function in mito and chloroplasts
- mito and chloroplasts have own DNA arranged in covalently closed circular form like B
- many signs of B are in eukaryotic organelles
what is the earliest evidence of microbial life?
stromatolites
how were ancient stromatolites formed?
phototropic filamentous bacteria
how were modern stromatolites formed?
phototrophic O2-evolving cyanobacteria
how do we use DNA to determine evolutionary history?
- DNA record of past evolutionary events
- determine phylogeny
what is phylogeny?
evolutionary history of organisms