Lecture 8 - Origins of Life on Earth Flashcards
How were simple cells created?
Abiotic synthesis of small organic molecules produced macromolecules which were packed into protocells that then became self-replicating.
How is the fossil record biased?
It favors species that existed for a long time, were abundant and widespread, and had hard shells or skeletons that could be fossilized.
How is the Hadean era characterized?
It is when the Earth and its geologic features formed and life did not exist yet.
What is the RNA world hypothesis?
It proposes that life originated from lightning or UV light reacting with the atmosphere to form H-cyanide which reacted with iron to sugars and then RNA. This was used to create the first protocells.
What are protocells?
They are the first cells formed from RNA that can carry out reproduction and metabolism, both processes necessary for life.
What is a vesicle?
It is a fluid-filled compartment, enclosed by a membrane that allows protocells to reproduce and pass on heritable traits.
How is the Archaen eon characterized?
The earliest conclusive evidence of prokaryotes was found dating back about 3.5 billion years ago. Stromatolites/prokaryotes were Earth’s sole inhabitants for about 1.5 billion years. Cyanobacteria were Earth’s first photosynthesizing prokaryotes.
How is the Proterozoic eon characterized?
About 2.5 billion years ago the great oxidation killed many anaerobic organisms. The first eukaryote appeared about 1.8 billion years ago and the first multicellular eukaryote appeared about 1.2 billion years ago.
What is endosymbiosis?
It is the theory that eukaryotic cells are formed by a host cell engulfing prokaryotic cells that entered the cell as undigested prey or parasites but then became mitochondria or plastids.
What is the current theory on the formation of organelles?
Serial endosymbiosis
What are 5 similarities between mitochondria, chloroplasts, and bacteria?
- Divide by binary fission
- Have smaller ribosomes than eukaryotes
- Have ribosomes to translate and transcribe their DNA into proteins
- Have circular DNA
- Have genomic similarities
How did organisms transition from unicellular to multicellular?
Through the segregation of function.
What was the Ediacaran Biota?
The first major diversification event that occurred about 670-550 million years ago in which the oldest macroscopic eukaryotes are found.
