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What is Life?

What is Life?. Living organisms: are composed of cells are complex and ordered respond to their environment can grow and reproduce obtain and use energy maintain internal balance allow for evolutionary adaptation. Fig. 1.1. mitochondria. Fig. 1.1(continued). The Nature of Science.

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What is Life?

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  1. What is Life? • Living organisms: • are composed of cells • are complex and ordered • respond to their environment • can grow and reproduce • obtain and use energy • maintain internal balance • allow for evolutionary adaptation

  2. Fig. 1.1 mitochondria

  3. Fig. 1.1(continued)

  4. The Nature of Science Science aims to understand the natural world through observation and reasoning. Science begins with observations, therefore, much of science is purely descriptive. Science uses both deductive and inductive reasoning.

  5. The Nature of Science Deductive reasoning uses general principles to make specific predictions. Inductive reasoning uses specific observations to develop general conclusions.

  6. The Scientific Way of Knowing: Inductive and Deductive approaches define the Scientific Method Often, scientific investigations starts with Induction and moves to Deduction Theory (Hypotheses) Observations, Previous Research Hypotheses Induction (specific to general) Deduction (general to specific) Experiments

  7. A scientific theory - is a body of interconnected concepts - is supported by a large fundament of evidence and scientific reasoning (usually the testing of numerous hypotheses) - expresses ideas of which we are most certain

  8. Charles Darwin evolution:modification of a species over generations -“descent with modification” natural selection: individuals with superior physical or behavioral characteristics are more likely to survive and reproduce than those without such characteristics

  9. One Piece of Darwin’s Induction Similarity of related species - Darwin noticed variations in related species living in different locations

  10. Another piece of Darwin’s Induction Population growth vs. availability of resources -population growth is geometric -increase in food supply is arithmetic

  11. Evolutionary Deductive Evidence Fossil record - New fossils are found all the time - Earth is older than previously believed Mechanisms of heredity - Early criticism of Darwin’s ideas were resolved by Mendel’s theories for genetic inheritance.

  12. An Evolution by Natural Selection Primer • Mutations and their various combinations (hence new varieties) do not arise because they are needed -- they arise by chance. • Mutations merely furnish random raw material for evolution, and rarely, if ever determine the course of the process. • Natural selection is the differential reproduction of genotypes (genes). Cumulative selection is a powerfully constructive force, caught in action many times by evolutionary biologists. • Evolution is, quite simply, the change in the genetic composition of a population over time.

  13. More Evolutionary Deductive Evidence Comparative anatomy - Homologous structures have same evolutionary origin, but different structure and function. - Analogous structureshave similar structure and function, but different evolutionary origin.

  14. Homologies of Religions and Languages

  15. Homologous Structures

  16. Homology vs. Analogy

  17. Homology vs. Analogy Pterosaur Bat Bird Figure from the National Center for Science Education

  18. More Evolutionary Deductive Evidence Molecular Evidence - Our increased understanding of DNA and protein structures has led to the development of more accurate phylogenetic trees.

  19. The Homeodomain, a protein structure found in a large family of Transcription Factors, and responsible for binding DNA and regulating target genes

  20. Fig. 1.14

  21. The 3 Domains of Life on Earth

  22. Holotype specimen of Juramaiasinensis, Beijing Museum of Natural History (BMNH) PM1343B. Z-X Luo et al.Nature476, 442-445 (2011) doi:10.1038/nature10291

  23. Unifying Themes in Biology Cell theory -All living organisms are made of cells, and all living cells come from preexisting cells. Molecular basis of inheritance - Genes, which control living organisms and are passed from one generation to the next, are found in DNA. DeoxyriboNucleicAcid

  24. Unifying Themes in Biology Cells - information processing systems - Cells process information stored in DNA as well as information received from the environment. Emergent properties • New properties are present at one level of organization that are not seen in the previous level. Evolutionary change - Living organisms have evolved from the same origin event. The diversity of life is the result of evolutionary change. Evolutionary conservation - Critical characteristics of early organisms are preserved and passed on to future generations.

  25. Unifying Themes in Biology Structure and Function -The function of a molecule is dependent on its structure. -The structure of a molecule can often tell us about its function. The DNA Polymerase III Beta Subunit (E. coli) with bound DNA

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