Lecture 1 What is Biology Biology the science of living things and their interactions with each other and the physical world Science attempts to explain nature by generating and testing alternative explanations Do climatic differences cause biome differences Alphonse de Candolle 1855 Wladimir K ppen temperature ranges cold warm hot moisture ranges dry moist wet Nine climate types cold dry cold moist cold wet warm dry warm moist warm wet hot dry hot moist and hot wet Searched for link between climate and biome type Lecture 2 How do experiments test hypotheses controlled experiment Fair test values of only one independent variable differ others held constant controlled independent variable Input manipulated causal variable stimulus values vary to see if this causes a change in outcome dependent variable Outcome variable effect response values may vary in response to changes in values of independent variable in math x is independent variable y dependent variable y f x values of y a function of values of x Why do we want to test alternative hypotheses Biological research is often motivated by curiosity Basic research is designed to describe or explain nature to satisfy one s curiosity Such research may lead to important applications Or generate new questions e g list species in an area Hypothesis testing for practical reasons is called applied research Types of evidence circumstantial evidence circumstances usually linked to cause e g wet street is usually caused by rain thus wet street in morning supports the hypothesis that the pitter patter on roof last night was caused by rain correlational evidence extent to which values of two variables which have been predicted to be linked are correlated experimental evidence direct or indirect manipulation of independent causal variables Lecture 3 Why do gazelles leap when being chased causal question Question about cause of puzzling observation e g Why does vegetation change from place to place Why do giraffes have long necks hypothesis plural hypotheses Possible cause of puzzling observation possible explanation planned test Conditions to test a hypothesis prediction Statement of expected future outcome of test assuming that hypothesis is correct Bias a tendency or inclination in favor of one explanation or belief that prevents unprejudiced consideration of alternatives variable Characteristic property trait with values that differ e g the number of times the gazelle stotts student heights Opposite of constant value Quantity magnitude number or rank of a variable e g values of the gender variable are male and female values for the height variable are 5 10 6 2 deduction If and then reasoning hypothesis planned test gives prediction expected result Patrick Dampare 1 observed result Outcome evidence data compare with prediction conclusion hypothesis supported contradicted or not sure constant Characteristic with values that do not differ e g number of noses in a group of students correlation Mutual or co relation of two or more things parts variables The placebo effect Placebo Latin for I will please Defined in 1811 as any medicine adapted more to please than to benefit the patient Was widespread in medicine before real medicine became more reliable The end of practicing placebo as treatment may have ended in 1890 How do experiments test hypotheses II Clinical research Extremely important applied research Medical researchers must know everything about how to run controlled experiments Why is this important Because if they mess this up people may die Goal To obtain information about adverse drug reactions and efficacy of drug Health authorities must give approval before a clinical trial starts This is evidence based medicine Pre clinical studies before testing in humans In vitro Test drug on cell cultures in test tubes In vivo Test drug on animals Phase 0 pilot studies First human trial A very low dose is given to 10 15 volunteers to see if there are any unexpected effects on the human body or how the body affects the drug Sometimes many similar drugs are tested in the same trial and then ranked by performance Phase 1 First real clinical human trial Safety Tolerability Effect Dose ranging Takes place in a clinic usually independent of the pharmaceutical company Test subjects are observed continuously Test subjects usually 20 100 healthy volunteers Occasionally also tested on terminally ill cancer or HIV patients Phase II Larger test group 100 300 of volunteers and patients Assess efficacy Assess dosing requirements Monitoring safety Some tests may be randomized clinical trials subject receives either the drug or placebo standard treatment Phase III The final assessment Randomized clinical trials on large groups 300 3000 Expensive and time consuming Patrick Dampare 2 2 Growth occurs when new cells arise by cell division a process in which parent cell parts duplicate and separate into two sets What in Sperm and Eggs Contain the Hereditary Instructions cytoplasm fluid inside cells nucleus Dark centrally located spherical organelle inside most body cells and in sperm and egg cells Cell Division Theory 1 Paired chromosomes duplicate before mitosis 2 Chromosomes move to center across from like chromosomes 3 Sets move to opposite sides of cell 4 Cell parts outside nucleus duplicate cytokinesis new cell membrane forms cell wall in plants Chromosome duplication and reduction division meiosis chromosomes in parent cells 6 duplication 12 first division 6 second division 3 sperm or egg fertilization 3 3 6 Meiosis takes place only in the reproductive organs Chromosome Theory of Inheritance 1 Chromosomes contain hereditary instructions 2 Transmission to new body cells occurs during mitosis when dividing cell duplicates its chromosomes and passes one set to each new cell 3 Sperm and egg cells produced by meiosis contain half the chromosomes 4 Transmission of hereditary instructions to offspring takes place when sperm enters egg to produce zygote with complete set of chromosomes Lecture 9 What do mating adults transmit to their young II Mitosis Takes place in all cells that are growing body cells Cell division Before mitosis starts DNA duplicates The duplicated DNA coils up and condenses into chromosomes Humans have 46 chromosomes or 23 homologous chromosome pairs One half comes from your mother maternal and the other half from your father paternal Meiosis Where does meiosis take place Only in the gonads What is the goal of meiosis To produce gametes or sex