Card Set Information
Showed that mimicking prebiotic conditions in the lab could result in the production of the 20 most common amino acids.
Proteins were originally thought to be the heritable information.
Peptide Nucleic Acid
Similar to RNA
Can be generated under ‘prebiotic conditions’
Woese/Crick/Orgel proposed that RNA could catalyze reactions.
RNAs can self-replicate, cut and elongate oligonucleotides
present in many of the oldest (slowest evolving) and critical cellular processes
transcription and translation, cofactors
Can store and transmit information (and is subject to natural selection)
High local concentrations speed assembly
RNAs can polymerize in the presence of clay (montmorillonite)
Why RNA -> DNA?
DNA allows for specialization in cells, DNA could store genetic info while RNA could be a cell messenger.
DNA is more stable than RNA
due to the deoxyribose sugar is less reactive
double-strandedness (ds) shields information from unwanted interactions
DNA replication has proof
reading systems lacking in RNA replication
ds also provides an inherent error-correction
Higher stability = lower mutation rates = high fidelity = longer genes and genomes
More information and more complexity
Adhesins-proteins that recognize and bind specific substrates
Motility-flagella, fimbrae (get where you need and attach)
Virulence is not directly selected for, it's a by-product of selection on other traits.
Short sighted evolution
A pathogen will experience many generations within a host that makes it well-adapted to its host before it can be transmitted.
Traits for growth at the cost of transmissibility may rise to high frequency.
Pathogenicity and transmissibility shape the alleles that rise to high frequency.
Disease transmitted by physical contact have a reduced fitness.
Mutualisms are not important to the survival of either species, but engage in mutualism while the other species is around.