A2.1 Origins of Cells Flashcards
On prebiotic earth there was ___ but no ____ and higher concentrations of ___ and ___ than there are now
water, free oxygen, carbon dioxide, methane
What did the gases on prebiotic earth cause?
High temperatures and UV light penetration. This may have caused a variety of carbon compounds to form spontaneously.
Possible scenarios for the origin of life on earth
Ocean surface (tidal pools), Panspermia, Undersea thermal vents
Explain the Ocean surface/tidal pools theory for the origin of life on earth
Suggests that life formed in a tidepool, pond or on moist clay on the primeval earth. Gases from volcanoes would have been energized by UV light or electrical discharges to form prebiotic molecules.
Explain the Panspermia theory for the origin of life on earth
Proposes that living organisms were “seeded” on earth as passengers aboard comets and meteors
Explain the Undersea thermal vents theory for the origin of life on earth
Suggests that life may have arisen at ancient volcanic vents. This environment would provide the necessary gases, energy and a possible source of catalysts.
MR H GREN acronym
Movement
Response
Homeostasis
Growth
Reproduction
Excretion
Nutrition
What are the processes in MR H GREN
Processes that are required to maintain life but they don’t explain life itself.
Why are viruses not considered to be living?
They aren’t cells and do not have organelles that can carry out metabolic rxns. They can only replicate with the help of a host cell.
The four main processes need for the spontaneous origin of life on earth
- The non-living synthesis of simple organic molecules
- The assembly of these molecules into polymers
- The origin of self replicating molecules that made inheritance possible
- The packaging of these molecules into membranes with an internal chemistry different to that of their surroundings
What was the Miller-Urey experiment?
The Miller-Urey experiment (1953) simulated early Earth conditions to test the origins of life theory.
Set-up: Miller and Urey used a closed system with water, methane, ammonia, and hydrogen, representing early Earth’s atmosphere. They heated the water (ocean) and applied electric sparks (lightning) to mimic natural processes.
Results: After a week, they found organic molecules, like amino acids, had formed—key building blocks for life.
Why was the Miller-Urey experiment significant?
This showed that organic compounds could form naturally under early Earth-like conditions, supporting the idea that life’s building blocks could originate from non-living matter.
Phospholipids have a ____ head and a ___ tail
Hydrophilic, hydrophobic
What is formed when phospholipids are placed in water
Vesicles, creates an isolated internal environment where optimal conditions can be maintained
What properties of RNA suggest that it is likely to have been the first genetic material?
- It can be formed from simple molecules called nucleotides
- It can make copies of itself
- It can catalyse rxns
