L17: Evolution of Life Flashcards
What was the main theory for the origin of earth and what are the steps?
Formation of earth (big bang)
Stable Hydrosphere
Prebiotic chemistry (soup)
Pre-RNA world
RNA world
First DNA
LUCA
What are the major transitions in the evolution of like?
RNA as gene and enzyme - DNA protein
Prokaryotes - Eukaryotes
Primate societies - Human societies
What is an example of an experiment used to replicate the origin of life?
Miller-Urey Experiment
What took place in the Miller-Urey experiement?
A heat source and water was used to replicate lava and water, then gases that provided the composition of the atmosphere were used which produced nucleotides
What were the downfalls of the Miller-Urey experiment?
It was done in a reducing environment, considered unlikely
The flask (silica) contributed towards the organic products
What did other experiments use to replicate the beginning of earth?
-A neutral atmosphere (complex gases)
-Arrival from space - meteorites
-Mineral (clay) catalysts and adsorbents - act as templates
-Deep sea vents - mineral rich water, sites of abundant life
What is the progenote?
An organism still in the process of evolving the relationship between genotype and phenotype
What was the process of the creation of the progenote?
Prebiotic soup - Self-replication - Cellularization - DNA genome - Invention of TLN - progenote
What was the hypothesis C.Woese and G.Fox put forward?
That the LUCA was a progenote
Why is RNA thought to have similar function to proteins?
As it can fold which provides different functions
What came first in evolution?
RNA
What is the main functional RNA?
mRNA
Which RNA has catalytic activity?
rRNA - for protein synthesis
What is the main proof that there was an RNA world?
The ribosome - removal of the protein still allows activity of the ribosome
What is the difference of RNA to DNA?
-Uracil instead of Thymine
-2’-OH making it chemically unstable but increases flexibility
Why is the instability of RNA advantageous?
As it allows folding of ssRNA into complex structures
What are the features of RNA?
-Stores genetic information
-Scaffolding
-Carries genetic info
-Recognition
-Catalytic activity
-Template
-Structure
What are examples of RNA storing genetic information?
In RNA viruses like HIV
Where is catalytic activity used in RNA?
In ribozymes
What are the different ways RNA can fold?
-Three-nucleotide bulge
-Four-stem junction
-Pseudoknot
-Hairpin loop
What is an example of a natural ribozyme?
A ribozyme from viroids: replicates in plastids which infects plants by cleaving long RNA required for replication
What is another use of RNA catalysis?
Self-splicing introns e.g. paramecium
What are examples of the biochemical reactions catalysed by ribozymes?
-Peptide bond formation in p.synthesis
-RNA cleavage and RNA ligation
-DNA cleavage
-RNA splicing
What are most of the biochemical reactions catalysed by ribosymes?
Artificial as they are done in vitro
What is an example of an artificial of ribozymes catalysing biochemical reactions?
Autophosphorylation using ATP
What is the process of ribozymes being used in autophosphorylation in vitro?
dsDNA is transcribed into RNA and is folded, ATP is added and the phosphate binds to one of the folded RNA molecules, the molecule is then separated
How does RNA enzyme mediate its own replication?
By using the catalytic site to make more of itself
What is the model of the order of events from complex organic molecules?
RNA world (RNA) - RNP world (protein) - LUCA (DNA)
What are the main arguments for the RNA primordial world?
-RNA polymerisation and replication can take place in vitro
-Genome of some viruses is based on RNA
-RNA molecules more complex than DNA (more functions)
-RNA can mediate catalytic reactions (Ribozyme)
-RNA is important in all organisms (particularly in protein synthesis)
-Synthesis of deoxyribose required ribose contained in RNA
-Nucleoside function as coenzymes is important to enzymes
What is the progenote model?
RNA being self-replicating (RNA world)
RNA leads to protein-based systems
DNA is self-replicating leading to RNA and proteins
