Cell evolution Flashcards
What came first: membranes or ‘genetics’?
- We do not know
- kinda like the chicken and the egg
- the origin dilema
Hadean Eon
Hadean eo: 4.6-4 million years ago. It consisted of erth coalescing,water, moon,core acceleration, magnetic field and late bombardment stage. the first biological molecules on Earth were formed by metal based catalysts on the crystalline surfaces of minerals. The Headean eon was hot and wet. The Hadean ocean consisted of active antle plumes, the same process seen in curren islanf formation, uniformitatiamism, and serpentination
Urey-Miller experiment
- 1953
- they provided conditions of the Hadean Earth (heat and a closed system)
- they added lightening which gave rise to biologicaly important molecules
- first demonstration of abiogenesis
Genetic Origins - RNA versus Chemical Chimera
- two genetic origin perspectives: top down (rna and ribosome first) and bottom up (the chemical chimera)
The Theory of Endosymbiosis regarding (eukaryotic) cellular*****
evolution
- symbiotic benefit for organisms that was eating
- one organism living inside of a cell of another organism for their mutual benefit
primary endosymbiosis versus secondary endosymbiosis***
- Primary endosymbiosis refers to the engulfment and establishment of a free-living prokaryote by a primitive eukaryotic host cell.
- secondary endosymbiosis occurs when a eukaryotic host cell engulfs another eukaryotic cell that has already undergone primary endosymbiosis, or eukaryotic host engulfs another prokaryote. eats twice
viral contribution to the evolution of the eukaryotic cell?****
- virus like started first because it has rna.
- vrsus early hypothesis
- regression hypothesis
- escaped genes hypothesis
the origin dilema
- life requires molecules that possess a crucial property: the ability to catalyze reactions that lead, directly, or indirectly, to production of more molecules like themselves
the ‘Theory of Abiogenesis’
- the idea that life arose from nonlife. Proposes that the first life forms generated were very simple and through a gradual process became increasingly complex
Top down approach
- Rna and ribosome first
- they are fundamental genetic markers to assess relatedness
- allow us to diferentiat domains
- rna is important to biochemical processes
-most commonly ascribes theory - rna in LUCA
the chemical chimera
- prebiotic soup
- combination of dna and rna building blocks
- molecules formed are more stable than formation from rna
- theoretical legs and experimental sustantialtion
- more recent
why is the chemial chimera theory more supported
- the origin of genetics is still fuzzy, but recent research better supports the chemical chimera
- increased chemical surface area for interaction
- increased molecular stability
- greater probability of rna-dna synthesis as opposed to bond-cementing
what is luca
the last universal common ancestor
- believed to have been a relatively simple, single-celled organism
- One of the key pieces of evidence supporting the concept of LUCA is the universal genetic code shared by all living organisms. The genetic code used by DNA and RNA to encode information is remarkably consistent across diverse forms of life.
bottom up
- the chemical chimera
- a hybrid molecule composed of an assortment of RNA and DNA
