Origin of LifeCh. 14.1 & 14.2(p.261-268)

One of the biggest questions:Where did we come from?Why life?

The early debate was:Biogenesis vs. Spontaneous Generation

What do these words mean?

BioGenesis

Spontaneousgenerate

Origin of LifeCh. 14.1 & 14.2(p.261-268)

Biogenesis = all living things come from other living thingsOk but what was the first

living thing? Was there a first?...

What came first the chicken or the egg?

Spontaneous generation = living things can arise from non-living things

Origin of LifeCh. 14.1 & 14.2(p.261-268)

Redi’s Experiment: Control: meat in open jarExperimental: meat in open jar covered by gauzeResults: No maggots formed on meat covered by gauze. Point Biogenesis

Origin of LifeCh. 14.1 & 14.2(p.261-268)

Spallanzani’s experiment:Control: boil broth, leave openExperimental: boil broth, seal

Results: no bacteria in sealed flask Point biogenesis

Origin of LifeCh. 14.1 & 14.2(p.261-268)

Pasteur’s experiment:Same as Spallazani’s but he came up with a way to leave it open.Control: boil and leave openExperimental: boil and leave open but neck is curvedResults: no bacteria in curved-neck flask

Biogenesis wins.

But we still don’t know how started.

Origin of LifeCh. 14.1 & 14.2(p.261-268)

14.2 The Earth is old.Radioactive isotope dating = very accurate measurement for age

Measures half-life decay = the time it takes half of the radioactivity to decay

Useful for things that aren’t changing: rocks, dead things

Origin of LifeCh. 14.1 & 14.2(p.261-268)

14.2 Miller’s Experiment:Put chemicals in flask that

were present in early earthSimulated conditions:

water, lightning….Results: amino acids formed by themselvesWhat do amino acids form?