Methods In Human Biology Notes PDF

2023-09-07 METHODS IN HUMAN BIOLOGY Chapters 1& 2 1 BioA11 Introduction to the Biology of Humans • COURSE OBJECTIVES: INTRO BIOA11 Fall 2023 Instructor: Karen Williams, PhD Office: SY210A Office hours: Virtual::Thursday 11301200h ; in-person: Friday 1600h-1630h, or by appointment See QUERCUS •...

2023-09-07 METHODS IN HUMAN BIOLOGY Chapters 1& 2 1 BioA11 Introduction to the Biology of Humans • COURSE OBJECTIVES: INTRO BIOA11 Fall 2023 Instructor: Karen Williams, PhD Office: SY210A Office hours: Virtual::Thursday 11301200h ; in-person: Friday 1600h-1630h, or by appointment See QUERCUS • • • _______________ _______________ _______________ • See syllabus • Aim for this week: • 1. To be individually competent at reading and evaluating scientific literature Email: [email protected] 2 1 2023-09-07 BioA11 Introduction to the Biology of Humans Introductions • Introduce yourself in the group and collect the following information • List topics in human biology you are interested in learning • Each person’s favourite plant or non-human animal • What do you take for a cold? 3 BioA11 Introduction to the Biology of Humans Lecture and Tutorial Schedule Dates 2023 Friday Sept 8 Lecture Week 1 Lecture topic/ TEST Chapter in Text Tutorial # cycle Methods in Biology 1&2 NONE Assignment Tutorial topic 2 Metabolism and disorders 3&4 1 cycle 1 (TUT 1, 3 & 5) TQ1 6 1 cycle 2 (TUT 2 & 4) TQ1 Tutorial Introduction: Scientific Method Introduction: Scientific Method 3 Cells out of control 4 Cell cycle and meiosis 7 2 cycle 1 TQ2 Tissues 5 Mendelian genetics 8&9 2 cycle 2 TQ2 Tissues Review1*; MIDTERM TEST 1 Mutations 10 3 cycle 1 TQ3 Interpreting data 10 3 cycle 2 TQ3 Interpreting data Populations and evolution Multifactorial traits and heritability Infectious diseases 11, 12 & 13 4 cycle 1 TQ4 Lactose tolerance 11,12 & 13 4 cycle 2 TQ4 Lactose tolerance 21 (& 23) 5 cycle 1 Presentations Case reports Review2*; MIDTERM TEST 2 Behaviour genetics & Review 21 5 cycle 2 Presentations Case reports 22.1 & 24 6 cycle 1 Presentations Case reports 6 cycle 2 Presentations Case reports September 11 and 15 September 18 and 22 September 25 and 29 October 2 and 6 FALL READING WEEK October 9 to 13 6 October 16 and 20 7 October 23 and 27 8 Oct 30 and Nov 3 9 November 6 and 10 10 November 13 and 17 11 November 20 and 24 12 Nov 27 and Dec 1 Monday Dec 4 4 2 2023-09-07 BioA11 Introduction to the Biology of Humans Lecture week 1: Methods in biology • The process of science • Hypothesis testing • Understanding statistics 5 © 2016 Pearson Education, Inc. The Process of Science Science is… • the discovery of something new and unknown • a body of knowledge collected using the scientific method • E.g., biology, the study of living organisms 6 3 2023-09-07 © 2016 Pearson Education, Inc. The Process of Science The scientific method • Making observations • Proposing ideas • Testing the ideas • Discarding or modifying ideas based on results 7 © 2016 Pearson Education, Inc. The Process of Science Make Observations. Hypotheses are proposed explanations for those observations. 8 4 2023-09-07 © 2016 Pearson Education, Inc. The Process of Science Your mom’s observation: It’s cold outside. Your mom’s hypothesis: “Dressing warmly will help you avoid a cold, because becoming chilled makes you more susceptible to illness.” - this is a testable hypothesis - it is possible to make predictions (“if,…then”) “Colds are generated by disturbances in psychic energy” is NOT a testable hypothesis. 9 © 2016 Pearson Education, Inc. The Process of Science • Scientific hypotheses • Testable: possible to evaluate • Falsifiable: potentially false • When a prediction based on a hypothesis is tested and shown to be correct, we say that the hypothesis is “supported”, not “proven”. • Why? • There might be other unmeasured (or unobserved) reasons why the prediction was correct 10 5 2023-09-07 © 2016 Pearson Education, Inc. The Process of Science Obs. 1: Fruits and vegetables contain much vitamin C. Obs. 2: People with diets rich in fruits and vegetables are generally healthier. Obs. 3: Vitamin C is an anti-inflammatory agent that reduces throat and nose irritation. Hypothesis: Consuming vitamin C decreases the risk of catching a cold. 11 © 2016 Pearson Education, Inc. The Process of Science Hypothesis: Consuming vitamin C decreases the risk of catching a cold. • Logically derived, based on observations • Can be tested • May be proven false 12 6 2023-09-07 © 2016 Pearson Education, Inc. 1.1 The Process of Science The logic of hypothesis tests • Hypothesis testing based on • Deductive reasoning – General principle to predict an expected observation 13 © 2016 Pearson Education, Inc. 1.1 The Process of Science The logic of hypothesis tests • Prediction is true • Hypothesis is supported but NOT proven • Prediction is false • Hypothesis rejected and disproven 14 7 2023-09-07 © 2016 Pearson Education, Inc. Hypothesis Testing The Experiment: To measure the effect of vitamin C on cold prevention Variables: factors that may change • Independent variables: those manipulated by the researcher • Vitamin C intake • Dependent variables: those not changed by the researcher; may change during the experiment and is being measured in the experiment • Susceptibility to illness upon exposure to virus 15 © 2016 Pearson Education, Inc. Hypothesis Testing Controlled experiments • Test the effect of a single variable • Limit possible alternate hypotheses • Differences in results should be due to treatment Control or control group • Similar to experimental subjects in all respects except that they do not receive the experimental treatment (change in the independent variable) 16 8 2023-09-07 © 2016 Pearson Education, Inc. Hypothesis Testing Steps for controlled experiments 1. Random assignment to control or experimental group 2. Identical participation for both groups except for the testing treatment 17 © 2016 Pearson Education, Inc. Hypothesis Testing Echinacea tea experiment • Hypothesis: Drinking echinacea tea relieves cold symptoms. • Independent variable: drinking tea • Dependent variable: relief from cold symptoms 18 9 2023-09-07 © 2016 Pearson Education, Inc. Hypothesis Testing Echinacea tea experiment • Hypothesis: Drinking echinacea tea relieves cold symptoms. 19 © 2016 Pearson Education, Inc. Hypothesis Testing Echinacea tea experiment • Hypothesis: Drinking echinacea tea relieves cold symptoms. • Independent variable: drinking tea • Dependent variable: relief from cold symptoms • Results: Experimental group felt echinacea tea was 33% more effective. 20 10 2023-09-07 © 2016 Pearson Education, Inc. Hypothesis Testing Minimizing bias in experimental design 21 © 2016 Pearson Education, Inc. Hypothesis Testing Double-blind, placebo-controlled and randomized experiments are the gold standard. • However, such controlled experiments on humans may sometimes be • Impossible • Dangerous • Unethical 22 11 2023-09-07 © 2016 Pearson Education, Inc. Hypothesis Testing • Model systems: used to avoid unethical or impractical tests on humans • Bacteria • Nematodes • Mammals (rodents, dogs, pigs, human cells) 23 © 2016 Pearson Education, Inc. Hypothesis Testing Relationships between factors (Correlation) Hypothesis: Stress makes people more susceptible to catching a cold. • Is there a correlation between stress and the number of colds people have caught? 24 12 2023-09-07 © 2016 Pearson Education, Inc. Hypothesis Testing Using correlation to test hypotheses • Results: The number of colds increases as stress levels increase. Caution! Correlation does not imply causation 25 © 2016 Pearson Education, Inc. Hypothesis Testing Using correlation to test hypotheses • The correlation might be due to other reasons 26 13 2023-09-07 © 2016 Pearson Education, Inc. Correlation does NOT imply causation! http://www.fastcodesign.com/3030529/infographic-of-the-day/hilarious-graphs-prove-that-correlation-isnt-causation#1 27 © 2016 Pearson Education, Inc. Understanding Statistics Overview: What statistical tests can tell us • Statistics in science • Evaluate and compare data • Statistical tests • Necessary because of the effect of chance • Examine variability between groups • Results from sample may extend to entire population 28 14 2023-09-07 © 2016 Pearson Education, Inc. 1.3 Understanding Statistics Overview: What statistical tests can tell us • Statistically significant • Results show a true difference between groups • Low probability that difference between groups is due to random chance • Researchers may infer that treatment had an effect 29 © 2016 Pearson Education, Inc. 1.3 Understanding Statistics The problem of sampling error 30 15 2023-09-07 © 2016 Pearson Education, Inc. Evaluating Scientific Information Scientific studies are published in scientific journals after a process of “peer-review” -scientists who did not participate in the experiment evaluate the strength of the data to support the hypothesis 31 BioA11 Introduction to the Biology of Humans For example Who are the authors? Where do they work? Which journal published this article? Bendesky et al 2017 Nature 544:434-453 32 16 2023-09-07 BioA11 Introduction to the Biology of Humans For example Who did what in the study? If you wanted to find the materials to repeat the study, who would you contact? Who did the peer review? Bendesky et al 2017 Nature 544:434-453 33 © 2016 Pearson Education, Inc. The Process of Science Some other important definitions Everyday use of fact: a thing that is known to be true Scientific use of fact: a direct and repeatable observation about our natural world Everyday use of theory: Untested ideas based on little information or unproven explanation Scientific use of theory: Powerful, broad explanation for a set of related observations • Based on well-supported hypotheses • Supported by diverse, independent lines of research 34 17 2023-09-07 © 2016 Pearson Education, Inc. The Process of Science Chronic stomach ulcers • Common belief: Ulcers are caused by acids and spicy foods. • Treatment: drugs to reduce acid; avoiding spicy food • New observation: Helicobacter pylori bacteria were found in most samples of ulcer tissue. 35 © 2016 Pearson Education, Inc. The Process of Science Chronic stomach ulcers • Accepted hypothesis: H. pylori infections cause stomach ulcers. 1. 2. 3. No reasonable alternative hypotheses are supported. The hypothesis has not been rejected by carefully designed experiments. The relationship between H. pylori and stomach ulcers follows the germ theory of disease. 36 18 2023-09-07 © 2016 Pearson Education, Inc. Evaluating Scientific Information Anecdotal evidence • Based on one person’s experience, not on experimental data. • Example: a testimonial from a celebrity 37 © 2016 Pearson Education, Inc. Evaluating Scientific Information • Be wary of anecdotes or incomplete surveys of scientific studies - media does have bias • Anyone can post information on the internet! • Advertising for some products are not subject to government regulation for accuracy (e.g. herbal supplements) • Examine the experimental design even when source is reliable 38 19 2023-09-07 © 2016 Pearson Education, Inc. Evaluating Scientific Information 39 BioA11 Introduction to the Biology of Humans Lecture week 1: Methods in biology • The process of science? • What is the process of science? • ____________________ • Hypothesis testing • Understanding statistics ____________________ • Hypothesis testing: • For example: ____________________ ____________________ • Understanding statistics • How do you read a graph? _____________ 40 20