1. Lecture 1 Introduction to Biology

2. The Diversity of Life  Biology is the study of living things  Living things can be divided into six kingdoms ArchaeaBacteriaProtistaFungiPlantaeAnimalia

3. What is Life?  Biology is the study of life - but what does it mean to be alive?  Ludwig von Bertalanffy – life is a system where the whole is greater than the sum of the parts  Living organisms and many non-living things share three properties 1.Complexity 2.Movement 3.Response to stimulation

4. Properties of Life  All living organisms share five basic properties 1.Cellular Organization  All living organisms are composed of at least one cell 2.Metabolism  All living organisms use energy 3.Homeostasis  All living organisms maintain stable internal conditions 4.Growth and reproduction  All living organisms grow and reproduce 5.Heredity  All living organisms possess a genetic system that is based on DNA (Deoxyribonucleic acid)

5. The Organization of Life  Living organisms function and interact with each other at many levels  These levels are organized in a hierarchy of increasing complexity: 1.Cellular Level 2.Organismal Level 3.Population Level 1. 2. 3.

6. Life is an Emergent Property  Each higher level of organization contains novel properties not present at the simpler level of organization  Birth rate & death rate – populations NOT individuals  Evolution – populations evolve biologically NOT individuals  These properties are termed emergent properties  They are a consequence of the structural organization that is the hallmark of life  They characterize many aspects of the living world

7. Five Themes That Unify Biology 1.Evolution  The gene frequencies change in a species over time  Causes include:  Genetic drift  Natural & artificial selection  Founder effects 2.The Flow of Energy  All living organisms require energy  The sun is the source of energy for most ecosystems  Plants capture energy via photosynthesis  They then act as an energy source for other organisms 3.Interaction  Interaction between organisms is critical for evolution  Social behavior occurs when organisms of the same species live in direct contact  Community dynamics occur when organisms of different species live in direct contact (Competition, Predation, Symbiosis) 4.Structure Determines Function  Biological structures are well suited to their function  This is true at every level of organization 5.Homeostasis  All living organisms act to maintain a relatively stable internal environment  Maintaining homeostasis requires energy and a lot of signaling back-and-forth between cells

8. How We Learn & Think  Our brains consist of billions of interconnected neurons  Our senses stimulate specific neuron pathways  Pathway residual sensitivity  Short term memory  Pathway physical changes  Long term memory  Caused by:  repeated stimulation  intense emotion  Sensory input & memory storage share the same circuits  This causes associations

9. How We Know Things  Our brains are great at two things  Recognizing patterns  Filling in sensory gaps (story telling)  Both of these can get us into trouble  Pattern Matching  Recognizing patterns that are not real  Not recognizing patterns that are real  Story Telling  Not checking to see that our stories are true  80% of personal disagreements between people begin as wrong stories each has told himself about the other’s motivations

10. Science: Testing Our Patterns & Stories  The Classic Scientific Method  Observation  Hypothesis  Test  Analysis (observation)  Modify hypothesis if necessary  The Null-Hypothesis  No hypothesis is valid if it cannot be tested  No test is valid if its results cannot disprove the hypothesis  The null-hypothesis is the formal statement of the hypothesis not being true and the test results that will support the null-hypothesis  Minimizing Results Based on Chance  Control groups: checking to make sure the same results would not occur without the test intervention  Statistical analysis: checking to see if the same result could be caused by chance (e.g. how likely is it to get 4 heads in a row when flipping coins randomly versus always starting with the coin on tails?)

11. How Scientists Think  Inductive Reasoning  Recognizing patterns  Is used by scientists to develop hypotheses about how the world works  Deductive Reasoning  Telling stories based on patterns  Uses accepted general principles as a “guide” to explain specific observations

12. Inference vs. Observation  An observation is limited to a description of actions or events without interpretation  An inference is a conclusion we draw based on what we observe  Inference or observation?  Example 1 (The cat is happy) Example 1  Example 2 (The cat is chewing on the plant leaves) Example 2  Example 3 (The cat is sleeping) Example 3  Example 4 (The cat is a female) Example 4

13. Theory and Certainty in Science  A theory is a set of hypotheses that have been tested many times and not rejected  It indicates a high degree of certainty  However, there is no absolute truth in science  Everything is open to more testing and reinterpretation  Acceptance of a theory is always provisional  Note:  To the general public, the word theory is often used to mean what a scientist would call a hypothesis, a lack of knowledge or a guess  To scientists, a theory represents that of which they are most certain, explanations supported by a wealth of evidence and experimental data

14. The Limitations of Science  Science is limited to organisms and processes that can be observed and measured  Many spiritual and religious explanations are beyond the scope of science  Most religious explanations do not allow formation of a realistic null hypothesis  However, the physiological and evolutionary basis of spiritual and religious experience is a current hot research topic in both neurophysiology & evolutionary biology  There are also practical limits  Science can provide options and understanding  Science cannot be relied upon to solve all problems  For example, what constitutes “acceptable risk” cannot be answered by science!

15. Four Theories Unify Biology & This Class 1.The Gene Theory  The information that determines what an organism is like is encoded in its genes  Genes are located along DNA molecules  The entire set of DNA instructions that specifies a cell is termed its genome 2.The Cell Theory  All living organisms are composed of cells  Cells are the basic units of life  All cells come from other cells 3.The Theory of Heredity  Genes represent traits of an organism and are inherited as discrete units  Chromosomal theory of inheritance: Genes are physically located on chromosomes 4.The Theory of Evolution  All living organisms are related to one another in a common tree of life  Diversity of the living world is the result of natural selection

16. The Brain & Study Implications  3 hours of study at one time is not effective for long term memory formation  Studying the same thing 20 minutes, 3 times a day for three days is more effective for long term memory formation  Using your brain to rephrase or rework the material is more effective for long term memory formation than repetitive reading or listening