Evolution /

What if I don’t believe it? Consider Acts 17:22-23 –Paul then stood up in the meeting of the Areopagus and said: "Men of Athens! I see that in every way you are very religious. For as I walked around and looked carefully at your objects of worship, I even found an altar with this inscription: TO AN UNKNOWN GOD. Now what you worship as something unknown I am going to proclaim to you.

What if I don’t believe it? Ask yourself if you even understand it? Realize that you really do believe it… at least, some of it. –Evolution is a theory, which means it’s complex –Parts of evolution are fact that no one contests

So, why should I care? Do you know why purebred dogs are more likely to have health problems than mutts? Do you know why 1.7 million Americans now contract “superbug” infections each year? Pay attention and maybe you’ll find out even more.

So, why should I care? It’s everywhere

Chapter 14 History of Life /

Biogenesis Biogenesis – all living things comes from other living things –From Greek bioun meaning “life” and gignesthai meaning “beginning” –Like the book of Genesis (the beginning) Spontaneous generation – the now abandoned view that life spontaneously arises –used to explain why maggots appeared on rotting meat

Biogenesis Redi’s experiment (1600s) –observed that maggots turned into flies and that maggots often seemed to appear after flies had been in the area –experimental group had meat covered with netting to keep flies out –control group had meat exposed to flies –demonstrated that maggots are produced from living flies

Biogenesis Redi’s experiment –Hypothesis: maggots develop from flies –Independent variable: exposure to flies –Dependent variable: development of maggots –Data: observed maggots (yes or no) –Conclusion: maggots form from flies, not spontaneously

Biogenesis Spallanzani’s experiment (1700s) –Tested the idea of a “vital force” –Boiled broth to kill microorganisms Sealed flask of exp. group Left control flask open –Critics said the heat killed the “vital force”

Biogenesis Pasteur’s experiment (1800s) –used a curved, but open, neck on a flask to keep microorganisms out of broth broth remained clean for up to a year once the neck was broken, broth was contaminated within a day

Cell Theory These experiments led to Cell Theory, which states: –All living organisms are made of one or more cells –Cells are the basic unit of structure and function in all living organisms –All cells come from other cells In general, evolutionary theory makes no effort to explain how life began, just how it has changed

Earth’s History The earth is about 4.6 billion years old Age is determined by radiometric dating –radioactive materials decay from their parent isotopes into daughter isotopes –this decay occurs at a specific rate, known as half-life

Earth’s History So, how did life begin? –Oparin and Haldane proposed in the 1920s that the earth’s early atmosphere contained large amounts of ammonia, hydrogen gas, water vapor and methane –These chemicals might have collected in water and, with the energy of lightning and solar radiation, combined into macromolecules, such as amino acids

Earth’s History Miller-Urey experiment –Tested Oparin and Haldane’s hypothesis by combining inorganic chemicals with electricity –Created organic materials, such as amino acids –Various revisions have been made to test differing hypotheses for the early atmosphere

Earth’s History But, didn’t I say evolution does not try to explain how life began? –Yes –Miller received his PhD in chemistry, not biology –But, science is interdisciplinary, so I said, “in general.” In general, evolutionary theory makes no effort to explain how life began, just how it has changed

Earth’s History That leads us to astrobiology –Formerly known as exobiology –Study of life in the universe –Organic molecules have been found in meteorites

Earth’s History Experiments have shown some organic molecules can form spontaneously –Microspheres are made of proteins that form a membrane a certain type of radioactive microsphere is now used in oncology –Coacervates are made of various molecules, including fats, amino acids and sugars

The First Life-Forms Read if you want to know more….

Check-up Describe the difference between spontaneous generation and biogenesis. Describe Redi’s experiment. Describe Spallanzani’s experiment. Describe Pasteur’s experiment.

Check-up How do you personally benefit from the research of Spallanzani and Pasteur? Describe cell theory. Describe the Miller-Urey experiment and its importance.