Lecture 1 BIO131 (1) PDF

Because learning changes everything.® Chapter 1 © 2020 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw-Hill Education. Chapter 1...

Because learning changes everything.® Chapter 1 © 2020 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw-Hill Education. Chapter 1 The Study of Life Introduction to Biology Biology—the science of life § Study the origins and history of life and once-living things § Study the structures of living things § Study how living things interact with one another § Study how living things function © McGraw-Hill Education 2  Biology is a Unified Science Biology + Chemistry + Physics= Science © McGraw-Hill Education  The study of life reveals fascinating characteristics of living species Biology also leads to the development of medicines and research tools that benefit the lives of people. Example: Neuroparasitology - the study of how parasites control the nervous systems of their hosts. © McGraw-Hill Education 4  The Study of Life What do biologists do? § Study the diversity of life § Research diseases § Develop technologies § Improve agriculture § Preserve the environment © McGraw-Hill Education 5  An Introduction to Biology Key Concepts: Levels of Biology Core Concepts of Biology Biological Evolution Classification of Living Things Biology as a Scientific Discipline Core Skills of Biology © McGraw-Hill Education 6  Figure 1.3: Levels of Biological Organization Access the text alternative for slide images. © McGraw-Hill Education 7  Levels of Biological Organization Atoms Organism Molecules Population Cells Community Tissues Ecosystem Organs Biosphere © McGraw-Hill Education 8  Core Concepts of Biology Evolution Structure and function Information flow, exchange, and storage Pathways and transformations of energy and matter Systems © McGraw-Hill Education 9  Biological Evolution Unity All life displays a common set of characteristics United by a shared evolutionary history Diversity Life has a diversity of form in diverse environments © McGraw-Hill Education 10  Evolutionary History 1 Life began on Earth as primitive cells between 3.5 to 4 billion years ago (bya) Those primitive cells underwent evolutionary changes to give rise to the species of today Evolutionary history helps us understand the structure and function of an organism © McGraw-Hill Education 11  Evolutionary History 2 Evolutionary change involves modifications of pre-existing characteristics Structures may be modified to serve new purposes Example: Walking limbs were modified into a dolphin’s flipper or a bat’s wing © McGraw-Hill Education 12 Figure 1.5: Modification as a Result of Evolution © McGraw-Hill Education 13  Two mechanisms of evolutionary change 1 Vertical descent with mutation Progression of changes in a lineage New species evolve from pre-existing species by the accumulation of mutations Natural selection takes advantage of beneficial mutations © McGraw-Hill Education 14 Figure 1.6: Vertical Evolution Example © McGraw-Hill Education 15  Two mechanisms of evolutionary change 2 Horizontal gene transfer Genetic exchange between different species Relatively rare Genes that confer antibiotic resistance are sometimes transferred between different bacteria species © McGraw-Hill Education 16  Figure 1.7: Horizontal Gene Transfer Bacterial species such as Bacterial species such as Escherichia coli Streptococcus pneumoniae © McGraw-Hill Education 17  Genomes and Proteomes 1 Genome The complete genetic makeup of an organism Genomics Techniques used to analyze DNA sequences Comparison of genomes of different species Proteome The complete complement of proteins of an organism Proteomics Techniques used to analyze the proteins of a species Comparison of proteomes of different species © McGraw-Hill Education 18  Genomes and Proteomes 2 The genome carries the information to make the proteome. Genomic and proteome analysis illuminate the evolutionary history and relatedness of all living organisms. © McGraw-Hill Education 19  Biology as a Scientific Discipline Science is the observation, identification, experimental investigation, and theoretical explanation of natural phenomena The Scientific Method is used to test theories Some scientists also gather information “Fact-finding mission” © McGraw-Hill Education 20  Biologists investigate life at different levels Different branches of biology study life at different levels using a variety of tools. Ecology, anatomy, physiology, cell biology, molecular biology, etc. As new tools become available, they allow scientists to ask new questions Systems biology aims to understand how emergent properties arise, at any level © McGraw-Hill Education 21  Figure 1.13 a and b: Biological Investigation at Different Levels a) Ecology—population/ b) Anatomy and physiology— community/ecosystem tissue/organ/organism levels levels © McGraw-Hill Education a: ©Diane Nelson; b: ©Purestock/SuperStock; 22  Figure 1.14 c and d: Biological Investigation at the Cell and Molecular Levels c) Cell biology—cellular levels d) Molecular biology— atomic/molecular levels © McGraw-Hill Education c: ©Erik Isakson/Blend Images; d: ©Northwestern, Shu-Ling Z hou/AP Images 23  Figure 1.13 e: Biological Investigation at the Systems Level Systems biologists may study groups of molecules. The microarray shown in the inset determines the expression of many genes simultaneously. e) Systems biology—all levels, shown here at the molecular level © McGraw-Hill Education ©Andrew Brookes/Corbis/Getty Images; (inset): ©Alfred Pasieka/Science Source 24  Hypothesis or Theory? 1 Hypothesis A proposed explanation for a natural phenomenon Based on previous observations or experiments Hypotheses must make predictions that can be shown to be correct or incorrect (must be testable) Additional observations or experiments can support or reject a hypothesis, but a hypothesis is never really proven Example: “Maple trees drop their leaves in autumn because of shortened hours of sunlight” © McGraw-Hill Education 25  Hypothesis or Theory? 2 Theory Broad explanation of some aspect of the natural world that is substantiated by a large body of evidence Allows us to make many predictions Also can never be proved true, but due to overwhelming evidence, may be very likely to be true Two key attributes of a theory: Consistent with a vast amount of known data Able to make many correct predictions Example “DNA is the genetic material” Overwhelming body of evidence supports this theory © McGraw-Hill Education 26  Understanding biology Curiosity is the key No rigid set of steps Two general approaches Discovery-based science Hypothesis testing © McGraw-Hill Education 27  Discovery-based science Collection and analysis of data without the need for a preconceived hypothesis Goal is to gather information Test drugs to look for action against disease Sequence genomes and proteomes Often leads to hypothesis testing © McGraw-Hill Education 28  Hypothesis Testing Five stages Observations are made regarding natural phenomena. These observations lead to a testable hypothesis that tries to explain the phenomena. Experiments are conducted to determine if the predictions are correct. The data are analyzed. The hypothesis is accepted or rejected. These steps comprise the Scientific Method © McGraw-Hill Education 29  Figure 1.14: Steps of the Scientific Method 1. OBSERVATIONS The leaves on maple trees fall in autumn when the days get colder and shorter. 2. HYPOTHESIS The shorter amount of daylight causes the leaves to fall. 3. EXPERIMENTATION Small maple trees are grown in 2 greenhouses where the only variable is the length of light. Control group: Experimental group: Amount of daily light remains Amount of daily light becomes constant for 180 days. progressively shorter for 180 days. 4. THE DATA 5. CONCLUSION The hypothesis cannot be rejected. A statistical analysis can determine if the control and the experimental data are significantly different. In this case, they are. Access the text alternative for slide images. © McGraw-Hill Education 30  Common features Data are often collected in parallel Control and experimental groups Differ by only a single variable Data analysis Apply statistical analysis to determine if the control and experimental groups are different because of the single variable that is different Are differences statistically significant? If the two sets are found not to be significantly different, we must reject our hypothesis. If the two sets of data are significantly different, we accept our hypothesis (though it is not proven) © McGraw-Hill Education 31  Example: Cystic Fibrosis 1 Affects about 1 in every 3,500 Americans Persons with CF produce abnormally thick and sticky mucus that obstructs the lungs and pancreas Average lifespan for people with CF is currently in their mid- to late 30s © McGraw-Hill Education 32  Example: Cystic Fibrosis 2 In 1945, Dorothy Anderson determined that cystic fibrosis is a genetic disorder In 1989, research groups headed by Lap-Chi Tsui, Francis Collins, and John Riordan identified the CF gene Discovery-based science, not hypothesis-testing, found the CF gene © McGraw-Hill Education 33  Hypothesis for function of CF gene 1 Hypothesis: The CF gene encodes a protein that transports chloride ions ( Cl- ) across the membrane of cells Led to experiments to test normal cells and cells from CF patients for ability to transport Cl- CF cells were found defective in chloride transport Transferring a normal CF gene into cells in the lab corrects this defect Chloride transport hypothesis is accepted © McGraw-Hill Education 34 Figure 1.15: CFTR Gene and Hypothesis Testing Access the text alternative for slide images. © McGraw-Hill Education 35  Hypothesis for function of CF gene 2 Results supported the hypothesis that the CF gene - encodes a protein that transports Cl across the plasma membrane A mutation in this gene causes it to encode a defective transporter protein, leading to a salt imbalance This imbalance affects water levels outside the cell, which explains the thick and sticky mucus in CF patients In this example, hypothesis testing has provided a way to accept or reject an idea regarding how a disease is caused by a genetic change © McGraw-Hill Education 36  Biology is a Social Discipline Within a lab, students, postdocs, technicians, and the PI work together Different labs often collaborate At meetings, scientists discuss new data – and debate! You can discuss science without having “all the answers” Science is a never-ending series of questions © McGraw-Hill Education 37  Figure 1.16: The Social Aspects of Science © McGraw-Hill Education ©Dita Alangkara/AP Images 38  Core Skills of Biology Ability to apply the process of science Ability to use quantitative reasoning Ability to use models and simulation Ability to tap into the interdisciplinary nature of science Ability to communicate and collaborate with professionals in other disciplines Ability to understand the relationship between science and society © McGraw-Hill Education 39