A2.1 Origins of cells Flashcards
(12 cards)
What were the key conditions on early Earth that allowed for pre-biotic chemistry?
Lack of oxygen and ozone, high CO₂ and CH₄, high UV radiation and temperature — allowing spontaneous formation of carbon compounds.
Why was the lack of ozone significant on early Earth?
It allowed ultraviolet light to penetrate the atmosphere, providing energy for chemical reactions.
What distinguishes living things from non-living things?
Living things show metabolism, growth, reproduction, homeostasis, and response to stimuli; non-living things do not.
Why are viruses considered non-living?
They cannot reproduce or carry out metabolism independently; they require a host cell.
Why is the spontaneous origin of cells difficult to explain?
Cells are complex; their origin required catalysis, self-replication, compartmentalization, and molecule self-assembly — conditions hard to test today.
What is the scientific challenge in studying early life?
The exact early Earth conditions cannot be replicated, and no fossil record of protocells exists.
What did the Miller–Urey experiment show?
It demonstrated that organic molecules could form spontaneously under simulated early Earth conditions.
Why is the formation of vesicles important in the origin of life?
Vesicles formed from fatty acids create compartments, enabling internal environments different from the outside — key for early metabolism.
Why is RNA considered the first genetic material?
RNA can self-replicate and has catalytic functions; ribozymes in modern ribosomes still catalyze peptide bond formation.
What is the significance of LUCA (Last Universal Common Ancestor)?
All organisms share genes and the genetic code, suggesting they descended from LUCA. Competing life forms likely went extinct.
How do scientists estimate the origin dates of life and LUCA?
Using molecular clocks, fossil records, and genomic analysis — showing life has evolved for billions of years.
What evidence supports LUCA evolving near hydrothermal vents?
Fossils in ancient vent deposits and conserved genes suggest early life originated in those chemically rich environments.
