Welcome to General Cell Biology

1. Welcome to General Cell Biology

2. Study Habits • Find out what works best for YOU • Try different methods • Combine methods • Use shorthand • Read the chapter BEFORE lecture and be prepared with any questions • Study EVERY day

3. What is science?To Know The Goal of Science1) deals only with the natural world2) to collect and organize information3) propose explanations that can be tested Seeks natural causes to phenomenon Therefore limited to things that we can OBSERVE and MEASURE

4. What is science?To Know • Explanatory • Testable • Reproducible • Predictive • Tentative

5. What is Biology Study of life Encompasses Ethology Evolutionary Biology Physiology Genetics Molecular Biology Morphology Systematics Ecology And more…..

6. Approaches Discovery- observational Uses inductive reasoning Hypothesis-based- experimental Uses deductive reasoning

7. Hypothesis based science Hypothesis- a tentative statement that proposes a possible explanation to some phenomenon or event Testable Tentative relationship is stated Simple and concise Falsifiable Accept or reject

8. Inferences, Predictions & Hypotheses • Inferences are a logical interpretation based on prior knowledge or experience • Predictions “guess” what will happen • Hypothesis presents a relationship, which attempts to explains what will happen • Specific, testable prediction about what will happen

9. Language of a hypothesis • Contain the dependent and independent variables • If leaf color change is affected by (related to) temperature , then exposing plants to low temperatures will result in changes in leaf color.

10. Language of a hypothesis Most commonly, hypotheses take three formats: • a question, "Does temperature affect fermentation?" • a conditional statement, "Temperature may affect fermentation." • an If, then statement, "If fermentation rate is related to temperature, then increasing the temperature will increase gas production.

11. Examples • If the diffusion rate (dependent variable) through a membrane is related to molecular size, (independent variable) then the smaller the molecule the faster it will pass through a membrane. • If the rate of photosynthesisis related to wave lengths of light, then exposing a plant to different colors of light will produce different amounts of oxygen.

12. Scientific method Observation Question Hypothesis Experimentation Controlled Replication Analysis of results Evaluate hypothesis 0

13. Why do I care about Hypothesis testing and scientific method? Used in every day life and decision making Ex: Medical- use scientific method to determine cause of patients ailment Understand the world around us

14. Scientific Theory • Explanation of something that has been substantiated by a large amount of data collected over multiple experiments • Best possible explanation at the time based on experiments and available data • Can be altered, revised, adapted or simply abandoned as new data becomes available

15. Reasoning Inductive- Extrapolate general principles from specific examples A conclusion is arrived at based on a set of observations Deductive- Extrapolate specific conclusions from general principles If A then B

16. Reasoning Inductive All observed crows are black. Therefore: All crows are black. Deductive All men are mortal Socrates is a man Therefore, Socrates is mortal

17. Experiments & Theories Experiments & hypotheses only test NEVER prove theories The very next experiment may falsify theory Always falsify a hypothesis, not prove it 0

18. Controls & Variables • Independent- single manipulated variable • Dependent- thing that is measured, counted or observed. Changes in response to independent • Controlled variables- things that are kept constant

19. Groups • Experimental- group that is exposed to the independent variable • Control group- group that is exposed to everything BUT the independent variable

20. Spontaneous Generation Redi’s blowfly experiment Living things arrive from lifeless matter Air had a “life force” Rotting meat, when left, produced flies Therefore, flies come from rotten meat

21. Spontaneous Generation Observation- Flies spontaneously appear on rotting meat Question- Does rotting meat produce flies? Hypothesis- If rotting meat is related to the creation of flies then any flask with rotten meat will produce flies Prediction- A flask of rotting meat will produce flies in 21 days Experimentation- 3 jars of meat were subjected to being open, semi-sealed with parchment paper or sealed while other variables remained identical

22. Analysis of results-No flies were present in closed jars, semi-closed jars had fly eggs on the parchment, open jars contained flies Evaluate hypothesis against results-Reject hypothesis as sealed jars did not produce flies and semi-sealed jars had fly eggs on the parchment paper ©Barrons 2009

23. What would happen if no control group was included?

24. In-class Exercise Get into groups Each group identify a scientific question, hypothesis and experimental outcome for each scenario Don’t worry about figuring out an experiment, just make up the results of one Decide if your outcome supports or refutes your hypothesis

25. Scenario 1-While hiking in the forest one day, you notice that while on the left side of the trail, the frogs are bright green, but on the right, they are a mottled green-brown color. Scenario 2- As a nurse, one of your patients presents with an unusually low temperature, but no other symptoms Scenario 3-You are fishing out in Puget Sound and find that all the other fishermen are pulling up salmon, but you are catching flounder.

26. Data Interpretation Data analysis is a body of methods that help to describe facts, detect patterns, develop explanations, and test hypotheses.

27. Data Interpretation Look At the Data / Think About the Data / Think About the Problem / Ask what it is you Want to Know Estimate the Central Tendency of the Data Look at the Exceptions to the Central Tendency (variation)

28. Data Interpretation • Average • Sum of numbers / number of numbers • Standard Deviation- measure of how variable the data is • Sampling error- difference between results from subset of data and the whole • Statistically Significant- unlikely to occur by chance

29. Data Interpretation

30. Organization of Life Life’s levels of organization define the scope of biology

31. Hierarchical organization Organized according to complexity Emergent properties Properties that were not present at the previous lower level and result from the specific arrangement and interactions between components “The whole is greater than the sum of its parts”

32. Environmental interactions Living organisms and their environments form interconnecting webs

33. Environmental Interactions Autotrophs Organisms that produce organic compounds from inorganic compounds “Producers” Heterotrophs Organisms that obtain nutrients from other organisms “Consumers” Decomposers Decay organic matter, releasing energy back into the ecosystem Saprobes

34. Common features of all living forms Order/organization Regulation Growth & Development Energy utilization/processing Response to the environment Reproduction Evolution