Presentation on theme: "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."— Presentation transcript:
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.
Theory Law Rule Model Hypothesis Auxiliary Hypothesis Ad hoc Hypothesis Working Hypothesis Fact Singular proposition General Proposition
Important concept. How many ways can two things be identical? How many ways can two things be different?
The Process of Science Observation – Question – (Induction) Logic – if... then... (Deduction) Hypothesis – H 0 (no difference between observed and expected) and H 1 (observed and expected are different) Experiment – Result – reject or accept hypothesis alternative hypotheses Remember proof in science is impossible
Where does the genetic information reside?
karyotype -DNA discovered in 1869 by Friedrich Miescher, a German Chemist. Extracted from the nucleus. -Walther Flemming described the chromosomes in 1882 Discovery of chromosomes and DNA But this is not evidence that genes are on chromosomes?
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.
What is in a typical egg? What is in a typical sperm? Eggs Sperm genetic information -> CHROMOSOMES
One egg, many sperm
Griffith 1928 Streptococcus pneumoniae The ‘transforming principle’ of Griffith, using ‘Rough’ and ‘Smooth’ bacteria in 1928 R strain S strain
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.
Timeline Darwin - Characteristics of parents passed on to young – 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