Evolution

1. Evolution Change in a population over time.

2. Why is the Russian prison system considered to be "ground zero" in the fight against TB? • What is responsible for the evolution of TB strains that are resistant to multiple drugs? • How does the misuse of antibiotics affect the evolution of disease-causing bacteria? Use the theory of natural selection to explain the growing resistance to antibiotics. • Why should we care about a resistant strain of TB in Russia?

3. Anwer questions while watching video. • http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html • Discussion. • http://www.pbs.org/wgbh/evolution/educators/teachstuds/unit6.html

4. The History of Life

5. The Origin of Life • Spontaneous generation – life arises from nonlife • Redi – tested idea that flies spontaneously come from rotting meat. -Not everyone was convinced of his findings.

6. Needham – Roman Catholic Theologian -Heated chicken and corn broths and poured them in a covered flasks. -The flasks cooled and microorganisms had grown. -Needham believed the microorganisms grew because of spontaneous generation. • Spallanzani – disagreed with Needham. - Suggested Needham’s broth had supported growth because they had been contaminated before being sealed and heated.

7. The Origin of Life • Louis Pasteur’s experiment • disproved spontaneous generation(mid 1800’s) • Flask 1 – only air was allowed to contact sterile nutrient broth • No microorganisms grew • Flask 2 – air and microorganisms were allowed to contact the broth. • Microorganisms grew • Theory of biogenesis – only living organisms can produce other live orgaisms.

8. Which came first, the chicken or the egg? • Biologists have accepted the concepts of biogenesis for more than 100 years • Biogenesis does not answer the question of how life began on Earth • No one will ever know for certain how life began on earth. We can only make hypotheses about conditions on early Earth.

9. Primordial Soup • Step 1: simple organic molecules must have formed (molecules that contain carbon) • Step 2: Simple organic molecules must have become organized into complex organic molecules (proteins, carbohydrates, and nucleic acids) • Hypothesized - life began in the oceans • Energy from sun and lightning triggered chemical reactions to produce small organic molecules from substances in the atmosphere • 1953 Miller and Urey (American) – replicated conditions in the lab and produced amino acids, sugars, and other molecules

10. The next step… • How did we get from simple organic compounds to complex organic compounds? • In the presence of heat, without oxygen, amino acids link to from proteins. • Continue to heat the complex organic compounds protocells developed.

11. The Evolution of Cells • The first true cells… • Prokaryotes that evolved from a protocell • Anaerobic (no oxygen present in atmosphere) • Autotrophs(photosynthesizing prokaryotes) evolved to inhabit harsh conditions (ie. cyanobacteria) • Cyanobacteriaproduced enough oxygen to support the formation of an ozone layer.

12. Endosymbiont Theory • Eukaryotes probably evolved from prokaryote cells • Theory proposes that eukaryotes evolved through a symbiotic relationship between prokaryotes • Evidence: • Chloroplast and cyanobacteria – resemble eachother • mitochondria and bacteria – some look similar • Chloroplast and mitochondria contain DNA that is similar to the DNA in prokaryotes • Today, some prokaryotes live in close association with eukaryotes • http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter4/animation_-_endosymbiosis.html

13. Selection Activity *Get into groups of 3’s: 1 recorder, 1 sorter, 1 picker 1. Obtain 2 groups of 1- squares: • Set 1 – 2 red and 8 green • Set 2 – 8 red and 2 green 2. Take set 1. Place the squares numbered side down randomly on the table. Pick a red square and record its number. Replace square. 3. Repeat Step 2 ten times. Clean up set 1. 4. Take set 2. Repeat steps 3 and 4.