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Chapter 1: Exploring Life

Chapter 1: Exploring Life. Unifying Themes in Biology. Evolution ~ biology’s core theme; differential reproductive success (sex!) Emergent Properties ~ hierarchy of life The Cell ~ all organism’s basic structure Heritable Information ~ DNA

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Chapter 1: Exploring Life

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  1. Chapter 1: Exploring Life

  2. Unifying Themes in Biology • Evolution~ biology’s core theme; differential reproductive success (sex!) • Emergent Properties~ hierarchy of life • The Cell~ all organism’s basic structure • Heritable Information~ DNA • Structure & Function~ form and function • Environmental Interaction~ organisms are open systems • Regulation~ feedback mechanisms • Unity & Diversity~ universal genetic code • Scientific Inquiry~ observation; testing; repeatability • Science, Technology & Society~ functions of our world

  3. Hierarchy of Organization • Molecule • Organelle • Cells • Tissues • Organ • Organism

  4. Feedback Regulation: Negative • Accumulation of an end product of a process slows that process • Example: sugar breakdown generates ATP; excess ATP inhibits an enzyme near the beginning of the pathway

  5. Feedback Regulation: Positive • An end product speeds up its production • Example: blood clotting in response to injury

  6. The Process of Science • The Scientific Method • Deductive reasoning • “If….then” Logic • Hypothesis vs. Theory

  7. Properties of Living things

  8. Early Views of life • Vitalism: The insistence that there is some big, mysterious extra ingredient in all living things • Led to idea of spontaneous generation • Flies came from dead animals • Mice came from Hay

  9. The Redi Experiment • Idea was challenged by scientist Francesco Redi in 1698. • Designed an experiment where 3 jars contained meat.

  10. Setup 1 • One Jar contained meat and had an open top which would allow the passage of flies. • (maggots would appear on the meat)

  11. Setup 2 • The second jar was covered with an airtight lid not allowing the passage of flies. • (no maggots would appear on the meat)

  12. Setup 3 • The third was covered by a screen allowing passage of eggs, but not flies. • (few maggots would appear on meat)

  13. Conclusion • Since the third setup would theoretically allow the passage of “ethers”, but no maggots appeared, it was implied that flies were the source of the maggots. • Led to the theory of Biogenesis • All life comes from preexisting life

  14. PROPERTIES of LIFE • Be made ofCells. • The Cell is the basic unit of life • Is self contained and possesses a barrier (membrane) which separates itself from the environment. • Two types of organisms. • Unicellular - One celled organism (Uni=1) • Multicellular - Many cells (Multi=”many”)

  15. PROPERTIES of LIFE • Living Things mustReproduce. • Must be able to create more of it’s own kind • Two types of reproduction: • Sexual - Two parent organisms combine genetic material to produce the offspring. • Asexual - When a single organism can divide or “bud” to create it’s offspring without another of it’s species.

  16. PROPERTIES of LIFE • Living things must Have DNA. • (Universal Genetic Code?)

  17. PROPERTIES of LIFE • Living things must Grow & Develop. • Growth refers to two processes. • Increase in the number of cells. • Increase in the size of cells. • Development refers to changes in the organism which occur through it’s life-span. • Includes cell differentiation. • Includes organ development • Includes aging & death.

  18. PROPERTIES of LIFE • Living things obtain & use energy. • Energy is used by all living things for growth, development & reproduction. • Life processes which result in “building” the organism ia known as Anabolism. • Life process where energy is extracted by “breaking-down” substances is called Catabolism.

  19. PROPERTIES of LIFE • Living things must Respond (or react) to their environment in some way. • Something which causes an organism to react is known as a Stimulus (stimuli). • The ability of an organism to react is called Irritability. • Most responses are geared for maintaining Homeostasis. • Homeostasis is a process where an organism maintains a stable internal environment so life can continue. • Some examples include temperature, pH, and water content of the cell.

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