Origin of Life Flashcards
(27 cards)
What are 2 hypotheses on how life originated? Which one has more evidence?
Abiogenesis (more evidence)
Panspermia (no evidence)
What is an abiotic?
A non-living thing
What is abiogenesis?
The natural process by which life evolved from non-living matter
The transition from non-living to living entities was a _______ and ______ process
complex, gradual
Abiogenesis assumes primitive earth contained ________ precursors that could be synthesized into complex organic compounds
inorganic
Organic compounds must contain what?
Carbon and hydrogen carbon bonds
Inorganic compounds that could lead to organic compounds include what?
Nitrogen, ammonia, carbon dioxide, methane, etc
Some conditions on primitive earth that allowed organic compounds to be created include…
- Atmosphere with vapour, nitrogen, CO2, ammonia, etc
- No O2
- Frequent lightning and UV radiation
What 1950’s experiment demonstrated abiogenesis?
Miller-Urey chemical experiment
Describe the method and results of the Miller-Urey chemical experiment
Method: Water vapour was sent to a flask containing methane, ammonia, and hydrogen. Electrical sparks were also fired to simulate lightning.
Result: The cooled water vapour contained organic compounds like amino acids.
Experiments similar to the Miller-Urey chemical experiment have shown formations of other organic ___________, like RNA, carbs, and lipids
macromolecules
Cell membranes are composed of _______
lipids
Lipids have a hydrophilic polar and and hydrophobic non-polar end. Describe how these join to form a lipid bilayer
The polar ends face the interior and exterior of the cell. The non-polar ends remain within the centre of the membrane.
Describe the main structures phospholipids can form
Liposomes: Donut sphere
Micelle: Timbit
Bilayer sheet: Rectangle
Regarding phospholipid structures, ________ are essential components of primitive cells. Why?
liposomes. The structure allowed nucleic acids and other polar compounds to become internalized.
What is a pre-cell?
Self-organized, spherical collection of lipids proposed as a stepping stone to the origin of life
What are ribozymes?
RNA enzymes that catalyze chemical reactions and facilitate self-replication.
How to ribozymes fit into abiogensis?
Ribozymes explain how the organic compounds could be replicated
Why evidence suggests are living things originate from one cell?
DNA can be transferred from any living organism into humans and still create the correct protein
Why do we believe organisms are related via common ancestors?
Evolution and genetic sequencing
What is the Last Universal Common Ancestor (LUCA)? What is the estimate on how long ago it lived?
The most recent population of organisms that are the common ancestors of all current life on Earth. Estimated to live around 3.5 to 3.8 billion years ago.
Why is LUCA considered to be a complex life form?
255 gene families were widespread amongst microbes, likely passed down from LUCA
LUCA gave rise to 2 kinds of simple cells: ______ and ______
bacteria, archaea
Why are deep ocean hydrothermal vents a strong candidate for the origin of life?
Thermophilic and hyperthermophilic bacteria and archaea are closest to the first branch point in the tree of life. Deep sea vents are also rich in hydrogen, CO2, and minerals.
