Introduction to Biology BIOS 1010 7A

1. Introduction to BiologyBIOS 1010 7A Sarah Jeffers

2. Chapter 1 Introduction to Life on Earth

3. Levels of Organization of Matter & Species Fig. 1-1

4. What Are The Characteristics of Living Things? • Living things are composed of cells • Living things are both complex and organized Fig. 1-8

5. The Cell Is the Smallest Unit of Life Fig. 1-2

6. The Cell Is the Smallest Unit of Life • A characteristic of all living things is organization. • Thus the name of all living things as organisms. All organisms consist of one or more cells The cell is the simplest structural and functional unit of life. Cells are the building blocks of all plants and animals. All new cells come from the division of pre-existing cells. Cells are the smallest units that perform all vital physiological functions. Nutrients O2 Division Wastes CO2 Cell Growth New cells The cell theory

7. The Domains and Kingdoms of Life The “Tree of Life” Fig. 1-11

8. How Do Scientists Categorize the Diversity of Life? • Categorizing life • There are exceptions to any simple set of rules used to distinguish the domains and kingdoms, but three characteristics are particularly useful • Cell type • The number of cells in each organism • Energy acquisition

9. How Do Scientists Categorize the Diversity of Life? • Classification into a domain or kingdom is based on 3 characteristics: 1. Cell type Bacteria Archaea Eukarya

10. How Do Scientists Categorize the Diversity of Life? • Classification into a domain or kingdom is based on 3 characteristics: 2. Number of cells Eukarya Bacteria Archaea

11. How Do Scientists Categorize the Diversity of Life? • Classification into a domain or kingdom is based on 3 characteristics: 3. Energy Acquisition Autotroph vs. Heterotroph Self-feeding Other-feeding Photosynthesis Digest external food Fungi, Archaea Bacteria Animals some Protists Plants, some Archaea some Bacteria some Protists

12. How Are Organisms Named And Classified? • Taxonomy – naming and classifying organisms • Scientific name: two part Latin name • Genus (closely related species) • species (populations that can interbreed)

13. How Are Organisms Named And Classified? • Taxonomy – naming and classifying organisms • Scientific name: two part Latin name • Examples: Sialia (Bluebirds) SialiasialisSialiamexicanaSialiacurrucoides (eastern) (western) (mountain)

14. How Are Organisms Named And Classified? • Phylogeny – evolutionary history • Similarities from a common ancestor • Not similarities from convergent evolution • Phylogenic trees

16. Review Questions List the three precepts of the cell theory. Can you describe the levels of biological organization? Can you name and briefly describe the three domains of life? Can you explain how scientists discovered that prokaryotes fall into two domains? Can you explain how scientists name and categorize diverse forms of life? Can you explain why phylogenetic classifications sometimes change?

17. What is Science? • Historical approaches to studying life • The belief that some events happen through supernatural forces (e.g., the actions of Greek gods) • The belief that all events can be traced to natural causes that we can comprehend (natural causality) • Corollary: Evidence gathered from nature has not been deliberately distorted to fool us

18. What is Science? • Scientific principles underlie all scientific inquiry • Natural causality is the principle that all events can be traced to natural causes • Natural laws apply to every time and place • Scientific inquiry is based on the assumption that people perceive natural events in similar ways

19. What is Science? • The scientific method is the basis for scientific inquiry • Observation • Question • Hypothesis • Prediction • Experiment or Observation • Conclusion

20. What is Science? • The scientific method 1. Observation of a specific phenomenon 2. The observation, in turn, leads to a question • The question leads to formulation of a hypothesis,based on previous observations, that is offered as an answer to the question • The hypothesis leads to a prediction, typically expressed in “if…then…” language • The prediction is tested by carefully controlled manipulations called experiments • The experiments produce results that either support or refute the hypothesis, allowing the development of a conclusion

21. What is Science? • The scientific method • Scientific experimentation tests the assertion that a single variable causes a particular observation • Controls are incorporated into experiments • Controls keep untested variables constant

22. The Scientific Method Fig. 1-4

23. The Experiments of Francesco Redi Fig. E1-1

24. The Experiments of Malte Andersson Fig. E1-2

25. The Scientific Method • Limitations of the scientific method • One can never be sure all untested variables are controlled • Conclusions based on the experimental data must remain tentative

26. The Scientific Method • Communication is crucial to science • Results of experimentation must be communicated thoroughly and accurately to other scientists for repetition • Repetition by other scientists add verification that findings can be used as the basis for further studies

27. The Scientific Method • Science can be accidental • In the 1920s, bacteriologist Alexander Fleming grew bacteria in cultures • One of the bacterial cultures became contaminated with a mold(Penicillium) • Fleming nearly destroyed the culture when he noticed the mold Fleming hypothesized that the mold produced an antibacterial substance

28. Scientific Theory • What does Scientific theory mean? • A scientific theory differs in definition from that of everyday usage • Many people use the word theory to mean hypothesis, or an “educated guess”

29. Scientific Theory • A scientific theory is a general explanation for important natural phenomena • It is extensively and reproducibly tested • If compelling evidence arises, a theory may be modified • Described as a natural law • New scientific evidence may prompt radical revision of existing theory • For example, the discovery of prions

30. Scientific Theory • The discovery of prions • Before 1980, all known infectious diseases contained DNA or RNA • In 1982, Stanley Prusiner showed that the infectious sheep disease scrapie is caused by a protein (a “protein infectious particle,” or prion) • Prions have since been shown to cause “mad cow disease” and diseases in humans • The willingness of scientists to revise accepted belief in light of new data was critical to understanding and expanding the study of prions