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GeoSci 110 (Exam 2) > Origin of Life > Flashcards

Flashcards in Origin of Life Deck (22):

Chemical Composition of Earth's Early (Archaen) Atmosphere

no free molecular oxygen in ocean atmosphere


Miller and Urey Experiments


- demonstrated that basic blocks of life (amino acids) can be synthesized from inorganic molecules

- amino acids, the basic building blocks of protein, are common place in our solar system


Significance of Murchison Meteorite

contained all 20 amino acids


Compound Synthesis (Molecules to Microbes)

abundant organic compounds found in the universe are concentrated and synthesized on earth (on clay materials)


Phospholipid Bilayer (Molecules to Microbes)

cell membranes (made up of fatty acids and alcohol)

- bilayers allow molecules to enter and exit do to their fluidity


Replication (Molecules to Microbes)

fatty acid membranes likely occurred independently at first;


Putting Them Together (Molecules to Microbes)

- simple organic compounds firm and eventually polymerize

- self replication molecules (RNA) occur

- self replicating machinery gets enclosed in a membrane

- true cells with RNA arise

- modern DNA replaces RNA


Role of Mineral Surfaces (Clay) in Concentrating and Organizing Organic Molecules

large surface area which serve as a template for organizing simple molecules in to more complicated molecules


Early RNA World as a Precursor to the Modern DNA World

- RNA Molecules are capable of catalyzing chemical reactions

- RNA in ribosomes (Ribozymes) catalyze their own self replication with out enzymatic mediators

- RNA plays a key part in expression of DNA indicating that RNA was a key agent in the catalysis and genetic coding in prebiotic world

- Protein may have been recruited to assist RNA replication then other metabolic processes

- finally may have enclosed in a membrane



organisms that live in extremely hot temperatures


Deep-Sea Hydrothermal Vents

likely candidate for where life began!


Green Sulfur Bacteria

found living around deep-sea hydrothermal vents


Archean-Aged Terranes of Pilbara Craton, Australia

oldest, non-metamorphasized sedimentary rocks



3.5 billion years old;

oldest fossils on Earth (not with actual organisms but were once mats of bacteria)



what forms stromatolites;

formed by the filamentous cyanobacteria (prokaryotes) that do oxygenic photosynthesis (doesn't produce any oxygen though)


Oldest Eukaryote Fossils

time is hard to pinpoint due to poor preservation and one's concept of what fossils of eukaryotes look like



2 Ga;

primitive forms of marine algae, single celled eukaryotes


3 Pieces of evidence implicating the early Evolution of Eukaryotes (endosymbiosis)

1.) size of organelles within eukaryotic cells is nearly identical to the size of few living prokaryotes to which they are metabolically similar

2.) mitochondria and chloroplasts have their own cell membranes just like prokaryotes do

3.) organelles have their own DNA, RNA, and Ribosomes (ssRNA sequences are similar to bacteria)


Evidence of fusion of Archaea and Bacteria in the evolution of Eukaryotes

- organelles have their own DNA, RNA, and Ribosomes; ssRNA sequences similar to bacteria

- proteins used by DNA to package their DNA in chromosomes, to transcribe DNA and to decode genetic messages remarkably similar in Eukaryotes

- based on ssRNA sequences, archaea are most similar to eukaryotes than bacteria


When did concentration of free molecular oxygen first start to rise?

"The Great Oxygenation Event"

- around 2.5-2.3 Ma

- due to oxygenic photosynthesis by cyanobacteria


What is the Ediacara Fauna?

soft bodied fossils preserved as impressions;

first multicellular animals

570 Ma (pre-Cambrian Period)


How old are the fossil embryos in the Doushantuo formation of China?

635 - 571 Ma