Exploring Theories on Life's Origin and Evolutionary Evidence

1. AIM: How are species related? • DO NOW: Why do scientists develop theories? Are theories facts? Why or why not?

2. Scientific theory of the origin of life

3. Francisco Redi:disproved abiogenesis

4. Louis Pasteur

5. Louis Pasteur • Pasteurization: boils liquids to kill microbes • He found microscopic organisms live in the air and water surrounding us

6. 1920’s Alexander Oparin and John Haldane: postulated conditions of early earth

7. Theory of primordial Soup • Hypothesized the early conditions of earth • Boiling oceans, volcanic eruptions, lightning storms • Atmospheric gases methane (CH4), ammonia (NH3), hydrogen (H2), and water (H2O). • Energy sources electric current through lightning storms and sun’s UV light • Early earth’s conditions interacted to form amino acids and small nucleic acids

8. 1953 Stanley Miller and Harold Urey

9. Miller and Urey • Actually created a closed system simulating early earth conditions • Observed small simple organic compounds were formed • Amino acids • Supports primordial soup hypothesis

10. From amino acids to the protocell • Amino acids combines to form proteins • Proteins evolved into RNA • RNA into DNA • Somehow cell membranes were synthesized it is still unclear how

11. How did the first types of cells develop? • Small organic compounds combine to create some types of membrane surrounding molecules and nucleic acid • This was called a protocell

12. First cells • Prokaryotes: no nucleus • Most likely archaebacteria

13. How then did we go from single celled prokaryotes to eukaryotes?

14. Lynn Margulus: endosymbiont theory • 1960’s explains how eukaryotic cells arose • Eukaryotic cells evolved from symbiotic relationships with prokaryotic cells • Evidence is seen in the DNA of both chloroplasts and mitochondria of eukaryotes which has more similarities to prokaryotic DNA and not eukaryotic

16. Alternative theory of origin of life: Deep sea vents • Life originated in the hydrothermal volcanic vents in the deep sea • Chemosynthesis: used the digestion of living things to make food • Photosynthesis uses light • Chemosynthesis uses molecules

17. Assessment • In your own words explain the scientific explanation of the origin of life

18. AIM: What are some pieces of evidence for evolution? • DO NOW: In your own words explain the scientific explanation of the origin of life. • Homework: Textbook Read pages 423-426 questions 3 and 4 pg 430

19. Organic Evolution

20. Organic Evolution • The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother. • Biological evolution, simply put, is descent with modification. • Small-scale evolution (changes in gene frequency in a population from one generation to the next) • Basically offspring displays different traits than parents • Large-scale evolution (the descent of different species from a common ancestor over many generations).

21. Organic Evolution • Changes in the genetic characteristics of a population over generations b) Genetic changes alter: proteins produced by organism • Changes in proteins affect: biochemistry, structure, appearance, reproduction, development, behavior, disease resistance, etc, etc.

22. AIM: How do scientists determine common ancestry? • Do NOW: 1- take out mondays homework Text pg 383 RC page 385 question 2 • 2- Take out Darwin’s finches handout • 3- EXPLAIN HOW each island has a different species of finch bird • HOMEWORK: 387 Reading Check. Page 389 question 2

23. Darwin’s descent with modification • Each generation shows a slight variation from the prior • Successful variations remain in the gene pool • Unsuccessful variations are removed

24. Family Tree Diagrams • used to show probable evolutionary relationships • some interpretations • multiple species can evolve from a single ancestor • many species have become extinct

25. Evolution • Change over time • Natural selection vs Artificial Selection • Natural selection: environmental conditions are the selecting agents • Artificial selection: humans are the selecting agents

26. Thursday 5/10/12 • AIM: how is evolution seen through history? • DO NOW: What do genes code for and how are genes related to descent with modification?

27. Evidence for Evolution I. Fossils show structural changes II. Comparative Sciences • result from common ancestry • the greater the similarity, the closer the evolutionary relationship and the more recent the common ancestor • III. The geological record • IV. Biogeography (Pangea)

28. Comparative Studies looks for Similarities Between Species 1. Cytology 2. Anatomy (structure) 3. Development embryology 4. Biochemistry

29. Cytology • cells with similar organelles appear in virtually all species • similarities in cell structure suggest that all organisms may have evolved from a single ancestor

30. Comparative anatomy • Compares the physical structures of organisms within different species • Homologous structures • Analogous Structures • Vestigial

31. Homologous Structures • structures in different species that are truly similar and develop in the same way • ex: vertebrate forelimbs • result from common ancestry d) may now be used for different purposes

32. Vestigial Structures (Vestiges) • useless structures “left over” from ancestors • ex: snakes have small leg bones inherited from their lizard ancestors c) human vestiges include: • appendix • coccyx (tail bones) • tonsils

34. Analogous structures • Similar in function but not structure • Gives evolutionary information about the natural environment the organisms were exposed to • Does not give common ancestry • Ex: wing of butterfly (chitin) • Wing of bat (bones)

36. What is the closet common ancestor of species I and N?

37. AIM: How do scientists determine common ancestry? • DO NOW: The study of homologous structures in mature organisms provides evidence for the evolutionary relationships among certain groups of organisms. Which field of study includes this evidence of evolution? 1- comparative cytology 2- biochemistry 3- geology 4- comparative anatomy Homework: Textbook Read pages 426-428. Questions 10-13 page 445

39. Comparative Embryology • different species go through similar stages of early development Studies the embryological development of organisms

40. ComparativeBiochemistry • different species have many of the same genes (DNA sequences) and produce similar proteins • provide the most precise information for determining evolutionary relationships

41. Comparing DNA Sequences For A Specific Protein Species #1: ATC CTA GCC TTT AAA Species #2: ATC CTT GCC TAT AAA Species #3: ATC CTA GCC TTT AAA Species #4: ATT CTT GCG TAT AAA 1. Which two species are most closely related? Answer: #1 and #3 2. Species #3 is _______closely related to species #4 than it is to species #2 Answer: less

42. AIM: How do fossils provide evidence for evolution? • DO NOW: What are homologous structures? How do they give evidence to a common ancestor?

43. Fossil Evidence for Evolution Fossils are: • naturally preserved remains of dead organisms • show structural changes resulting from evolution

44. Fossils are found in: • 1. Sedimentary Rock • 2. Burgess shale • 3. Ice • 4. Tar • 5. Amber

47. Types of Fossils 1. Complete organisms Molds and casts can be preserved in ice, tar or amber • Partial remains (ex: skeleton) 3. Imprints or trace fossils impressions left by organism 4. Petrified fossils gradual absorption of minerals turns the remains into a stone like material

48. Fossil Samples

49. Trace fossils Mold and cast

50. Petrified fossils Replacement