Notes for March 20. 2006

Obj SW

1. Record the experimental work of scientists dealing with the origins of life.
2. Record the direct and indirect evidence for evolution.

Notes

Definitions

Abiogenesis:The idea that life is created by non-living things.

Back in time: 200-300 years ago where does a person go to get something to eat? A market. An open air market. For meat, go to a hunter or butcher.

Way back, way back . . . ya cooked your meat, and covered the leftovers and put ‘em on the shelf. After a few days there might be bugs. Ya might think that the bugs actually came from the meat.

You might believe that mosquitoes came from puddles of water.

Scientists during that time believed that life came from non-living things.

Looking at Scientists . . .

Francesco Redi (1600’s)
--He put fresh meat in an open jar.
--Put the same kind of meat in a sealed jar.
--He observed that the meat in the open jar attracted flies and maggots. No flies in the sealed jar. The conclusion here is that the flies and maggots must come from some outside source, that they do not come from the meat.

Louis Pasteur
--Pasteurization is named for Pasteur.
--At Pasteur’s time, the prevailing belief was that Life came out of a prevailing force inn the air.
--Pasteur took broth (meat-based) and put it in a flask. He boiled it and allowed air to get to it through a tube.
--His control: the tube was s-shaped and would trap micro-organisms, but allow air to reach the broth
--His experimental flask was exposed to bacteria trapped in the tube, so bacteria grew in the broth.
--Conclusion? Life begets life. Life comes from living things.

Biogenesis: Life creates other life.

Differentiation between theology and science

Theology: Study of God. Theorizing and explaining the existence of God.
Science: Study of Nature. Experiments to find ways to explain the natural world through lots of supporting evidence.

Alexander Oparin
--Theorized that early Earth was extremely stormy, that there was a great deal of lightning.
--He further theorized that when lightning interacted with the atmosphere of Early Earth, the reaction created organic molecules (proteins, lipids, nucleic acids, carbohydrates).

Stanley Miller and Harold Urey (1953)
--Simulated Oparin’s theory in a lab
--Boiled water and trapped it in tubing with hydrogen, methane and other gasses that were present in Earth’s atmosphere.
--Delivered electrical charge to simulate lightning.
--They found that organic molecules (sugars and amino acids) in the water once it had cooled.

Protocell: A large, ordered structure enclosed by a membrane. It carries on some of the functions of life, such as growth and division. Doesn’t show all characteristics of life.

Lynn Margulis
--Symbiosis: two critters that live together
--She theorized that mitochondria and chloroplasts were once prokaryotic cells. They were taken in by cells, but not broken down.
Clues to back up this craziness . . .
--Chloroplasts and mitochondria have their own DNA.
--Chloroplasts and mitochondria are also the only organelles that have a double membrane
--Have their own ribosomes (small ones found in Prokaryotic cells
--Endosimbiant Theory

Charles Darwin
--Set out on a trip at the age of 22.
--Studied primarily tropical areas.
--Observed a great amount of biodiversity.
--He wrote a journal, drew pictures, collected specimens.

Darwin and Evolution
--All species show variation.
--All organisms produce more offspring than can survive.
--Because of this surplus of offspring, there is a struggle for survival.
--Some individuals have a better chance for survival “survival of the fittist.”
--Wrote “On The Origin of the Species”