A2.1 Origin of Cells

prebiotic conditions (6)

• very little oxygen

• lots of methane

• increased carbon dioxide

• higher temperature

• no UV protection from atmosphere

• lots of lightning

self-sustaining (this ability can be passed on)

using energy to maintain highly-ordered state

evidence that cells are living (4)

• each cell uses energy to maintain order

• some cells stop doing this and die

• cells produce more cells

• cells can live outside of the body and culture

what were the requirements of forming the first cell? (4)

• catalysis - control over reactions

• self-assembly of polymers

• compartmentalisation

• self-replicating molecules

what were the added components of the Miller-Urey experiment?

prebiotic gas mixtures and energy

what did the Miller-Urey experiment produce?

amino acids

how did vesicles spontaneously form?

due to phospholipids’ amphipathic properties which causes them to form bilayers, they were in the primordial soup

what are the reasons RNA is the presumed first genetic material? (4)

• RNA is self replicating

• RNA can act as a catalyst

• some viruses only have RNA

• RNA mutates at a higher rate

evidence for LUCA (3)

• universal genetic code

• ribosome structure

• enzymes that synthesise DNA and RNA

how many years ago was LUCA on Earth?

4.5 million years ago

how is dates of the LUCA estimated?

relationship between genome differences and the amount of time that has passed between common ancestors

evidence for the evolution of the LUCA near hydrothermal vents (3)

• common proteins were needed for environments that were anaerobic and high in hydrogen, carbon dioxide and iron

• condition found around hydrothermal vents, particularly white smokers

• contains minerals and temperatures that could have led to the spontaneous generation of carbon-based polymers