5.1.1 - Origin of organic molecules Flashcards
Summary of hydrothermal vent ecosystems
Food supply is not generated by photosynthesis.
The energy that sustains these deep-water communities is entirely sourced from Earth’s internal heat
Food webs support carnivores that feed on consumers supported by chemosynthetic primary producers.
It is thought that there is very little interaction of hydrothermal vent communities with surface water ecosystems (ie. The hydrothermal vent communities can thrive completely independently of solar-driven surface processes).
What was the purpose of Urey and Miller’s experiments?
They were investigating the idea that the atmospheric and physical conditions of early Earth enabled the formation of amino acids (which make up proteins, which are essential for functioning cells).
What did the precambrian period see?
The Precambrian period sees the development of the biosphere from the beginnings of life through the evolution of photosynthesis, eukaryotic cells, colonial and multicellular organisms.
What was the significance of U/M experiment?
The first work to demonstrate that abiotic (non-living) processes could generate the primary, essential components (amino acids) required for living organisms to evolve. It suggested that organic molecules could form naturally under conditions such as those of early Earth.
Also highlights the value of scientific models to reproduce certain conditions and make predictions and judgements based on them.
Summarise the U/M experiment.
2 chambers - one representing the ocean and the other representing the atmosphere (H2O, CH4, NH3, H2).
Electrical sparks were discharged periodically into the chamber containing the gases, to simulate the lightning that was theorised to have provided the energy for chemical reactions in Earth’s early atmosphere.
After a week, the condensed water had become red and turbid, and analysis showed that the water contained amino acids as well as lipids, sugars and other organic molecules.
The panspermia hypothesis suggests that:
- Organic life occurs everywhere in the universe
- The original precursor materials or microorganisms that led to life developing on Earth arrived from space on comets or meteorites rather than developing on Earth from abiotic precursors
Why do scientists support panspermia?
The fossil record indicates that organisms were definitely present on Earth within 200 million years of the beginning of the Archean eon, and possibly much earlier. This means that life on Earth started almost as early as it could have. The relatively short span of time between the stabilisation of conditions that could support life and the appearance of life increases the appeal of an extraterrestrial, panspermia origin for Earth’s organisms.
In a nutshell - if life ‘evolved’ on Earth, there should have been a much longer period of time spanning between the stabilisation of conditions and emergence of life.
What was on the Murchison meteorite?
Complex polymers, water-soluble organic acids, amino acids and ketones.
What was found on the Churyumov-Gerasimenko comet (orbiting Jupiter)
The amino acid precursors methylamine and ethylamine
Phosphorus, which is a vital component of adenosine triphosphate, an organic compound that provides energy to drive many processes in living cells.
Summary #2 of HV ecosystems
Hydrothermal vents are features on the deep sea floor where jets of sea water are ejected. The jets of sea water contain dissolved sulfides and sulfates, which support ecosystems in which chemosynthetic microbes produce carbohydrates and organic material that are consumed by browsers and filter feeders. In turn, these organisms are consumed by scavengers and predators.
3 HVs
Black smokers → eject very hot (350dc) sea water rich in dissolved iron and copper sulphides
White smokers → hot (250dc) sea water rich in calcium and barium sulfates
Alkaline vents → warm (60dc) rich in hydrogen and sulphur, dissolved silica, Ca Mg Ni Fe Co3 ions.
