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What is Science?

What is Science?. A way of knowing Based on repeatability Based on coming up with the most plausible answer from a suite of possible answers. A process of going from singular propositions to general propositions. General Proposition. Theory Law Rule Model Hypothesis Auxiliary Hypothesis

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What is Science?

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  1. What is Science? • A way of knowing • Based on repeatability • Based on coming up with the most plausible answer from a suite of possible answers. • A process of going from singular propositions to general propositions.

  2. General Proposition Theory Law Rule Model Hypothesis Auxiliary Hypothesis Ad hoc Hypothesis Working Hypothesis Fact Singular proposition

  3. Important concept. • How many ways can two things be identical? • How many ways can two things be different?

  4. Justificationism

  5. Falsificationism

  6. The Process of Science • Observation – • Question – (Induction) • Logic – if ... then... (Deduction) • Hypothesis – H0 (no difference between observed and expected) and H1 (observed and expected are different) • Experiment – • Result – reject or accept hypothesis • alternative hypotheses • Remember proof in science is impossible

  7. Where does the genetic information reside?

  8. Discovery of chromosomes and DNA • karyotype -DNA discovered in 1869 by Friedrich Miescher, a German Chemist. Extracted from the nucleus. -Walther Flemming described the chromosomes in 1882 But this is not evidence that genes are on chromosomes?

  9. Observations:Do both parents contribute equally to offspring? • What can we observe? • Casual observations—children often resemble parents, sometimes their mother, other times their father • Controlled crosses—when the same cross is set up twice, switching the sex of the parent, the results are the same.

  10. What is in a typical egg? What is in a typical sperm? • Eggs • Sperm • genetic information -> CHROMOSOMES

  11. One egg, many sperm

  12. Griffith 1928 Streptococcus pneumoniae • The ‘transforming principle’ of Griffith, using ‘Rough’ and ‘Smooth’ bacteria in 1928 R strain S strain

  13. Hammerling Exp.

  14. Hershey-Chase Experiment

  15. The Science behind the discovery that the genetic material resides in the chromosomes • Observation – offspring inherit traits from their parents. • Question – where does the information reside responsible for traits? • Observation - the nucleus appears to be important. • Logic – if we remove the nucleus from a cell it will not divide and grow • Hypothesis – the nucleus contains the hereditary information • Null Hypothesis – Removal of the nucleus from a cell will not affect development • Experiment – remove or kill nucleus • Result – cell does not develop – reject null hypothesis.

  16. Timeline • 1857 - Darwin - Characteristics of parents passed on to young. • 1869 – Friedrich Miescher – discovered ‘nuclein’ (DNA)‏ • 1882 – Walther Flemming – Chromosomes • 1928 – Griffith – transforming principle • 1930’s – Hammerling – Acetabularia nucleus • 1952 – Hershey-Chase Experiment • 1952 – Briggs and King – nuclear transplant exp. in frogs

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