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TEACHER NOTES

TEACHER NOTES. This PowerPoint was revised January 3, 2005. EVIDENCES OF EVOLUTION. Fossil Record Biochemical Comparative Anatomy Biogeography Observable Events. EVOLUTION IS. Genetic change in a population through time.

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TEACHER NOTES

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  1. TEACHER NOTES • This PowerPoint was revised January 3, 2005.

  2. EVIDENCES OF EVOLUTION Fossil Record Biochemical Comparative Anatomy Biogeography Observable Events

  3. EVOLUTION IS Genetic change in a population through time.

  4. On his journey around the world, Darwin found evidence of gradual change (evolution). Darwin cited evidences he found in fossil records, geographic distribution and homologous structures. Charles Darwin

  5. Today most evidences for evolution are grouped into five main categories: Fossil Record Biochemical Comparative Anatomy Biogeography Observable Events Evidences of Evolution

  6. Paleontology – study of fossils Fossil – remains or traces of an organism that lived long ago Remains: ex. bone, tooth, or shell Traces: ex. burrow, footprint, or imprint 1 - FOSSIL RECORD

  7. Most fossils are found in layered sedimentary rock In Relative Dating, the age of the fossil is determined by comparing its placement with that of fossils in other layers of rock. 1 - FOSSIL RECORD

  8. 1 - FOSSIL RECORD • The oldest layers on the bottom with the more recent on the top. • An index fossil also allows scientist to compare the relative age of a fossil.

  9. Comparing fossils from different layers shows: Life on Earth has changed Increased number of life forms 1 - FOSSIL RECORD

  10. 1 - FOSSIL RECORD • Radioactive dating is the use of half-lives to determine the age of a sample. Scientists calculate the amount of remaining radioactive isotopes it contains. A half-life is the length of time required for half of the radioactive atoms in sample to decay.

  11. THE GENETIC CODE Triplets of DNA nitrogen-base sequences that code for specific amino acids The amino acid triplet is the same in almost all organisms. 2 - BIOCHEMICAL

  12. The similarity of triplet DNA codes making-up amino acids shows: A probable common ancestor for all life on Earth 2 - BIOCHEMICAL

  13. “Universal” GENETIC CODE Similar genes Over the ages, the genetic code has passed unchanged (or nearly so) from parent to offspring. 2 - BIOCHEMICAL

  14. AMINO ACID SEQUENCING The amino acid sequence in a particular protein is compared between organisms. 125 45 1 67 8 27 2 - BIOCHEMICAL Number of differences from human hemoglobin

  15. Comparing amino acid sequence shows: Closeness of relationship A probable common ancestor 2 - BIOCHEMICAL Amino Acid Difference in Hemoglobin Compared with Human Amino Acid Sequencing is probably the STRONGEST evidence for relationships among organisms. Human hemoglobin has 146 amino acids

  16. Amino Acid Difference in Hemoglobin Compared with Human CLADOGRAM: diagram that shows the evolutionary relationship among a group of organisms. 100 20 150 50 0 40 30 10 Number of Amino Acid Differences 2 - BIOCHEMICAL B A C D Where would the common ancestor be? What organism belongs at each branch? E F G Common ancestor

  17. HOMOLOGOUS STRUCTURES structures with similar structure but different function ex: limbs of vertebrates (turtle, alligator, bird, mammal) Alligator Turtle Bird Mammal 3 COMPARATIVE ANATOMY

  18. Homologous structures show Similar genes Descent from a common ancestor Alligator Turtle Bird Mammal Ancient lobe-finned fish 3 COMPARATIVE ANATOMY

  19. VESTIGIAL STRUCTURES organs so reduced in size that they are nonfunctioning remnants of similar organs in other species ex: human tailbone, appendix, whale pelvis 3 COMPARATIVE ANATOMY

  20. Vestigial structures show: an organism’s evolutionary past a common ancestor with species that have similar structures that are still functioning 3 COMPARATIVE ANATOMY

  21. EMBRYOLOGY Embryos of different species may appear similar in early stages of development ex: vertebrate development 3 COMPARATIVE ANATOMY

  22. Comparison of similarities in embryos can show: Relationship to a common ancestor 3 COMPARATIVE ANATOMY

  23. GEOGRAPHIC DISTRIBUTION OF ORGANISMS organisms living widely apart (even different continents) may be similar because they share a common ancestor Beaver Muskrat Beaver andMuskrat Coypu Capybara Coypu andCapybara 4 - BIOGEOGRAPHY • Shows common ancestor

  24. Some changes in species have been observed and studied: 5 - OBSERVABLE EVENTS

  25. Observable events show that evolution is an ongoing process 5 - OBSERVABLE EVENTS

  26. Works Cited • “Geographic Distribution of Organisms” photo: Miller, Kenneth and Levine, Joseph. (2004). Biology. Prentice Hall.

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