Lecture 2 Flashcards
What is the surface origin hypothesis of cellular life first evolving?
‘warm little pond’
Primordial soup - organic molecules can form spontaneously
(unlikely due to hostile conditions on surface)
What is the subsurface origin hypothesis of cellular life first evolving?
Hydrothermal vents at ocean floor
More stable conditions
Constant source of energy - reduced inorganic compounds
What is the divergence of the lipid bilayer with the origin of cellular life?
Base layer - highly reduced compounds that can be oxidised
- Nucleic acids and RNA - self-replicating RNA molecules
- Proteins giving more capabilities - enzymatic RNA and proteins
- Organisms started to use DNA
What are the landmarks in biological evolution?
Early life probably dependent on H2 and CO2
Energy and carbon metabolisms diversify
Evolved into oxygenic photosystem using H2O
Oxygenation of atmosphere - turn water into H and O
What method was used to tell how related organisms were before molecular biology?
Phylogenetic methods
Extract DNA and analyse sequence
Look for universal markers like DNA, RNA and ribosomes
What is necessary of molecular markers used in diversity studies?
Universal
Contain variable and conserved regions
Not subject to horizontal gene transfer
Homologous
What is the potential chain of events in evolution of eukaryotes?
- Ancestor of mitochondria: separates eukaryote and archaea
- Formation of nucleus
- Ancestor of chloropast
What do fossils suggest as to when eukaryotes arose?
2.5 billion years ago
What is the endosymbiont theory of the evolution of eukaryotes?
Mitochondria: incorporation of aerobic chemo-organotrophic bacteria into a host cell
Chloroplasts: incorporation of phototrophic cyanobacteria into a eukaryotic cell
What is the hydrogen hypothesis of the evolution of eukaryotes?
Association of an archaeal host using H2 as energy source with aerobic bacterium
Produced hydrogen as waste product
Archaea and bacteria cell working together causing development of eukaryote
