apLectureNotes01 - CHAPTER 1 } INTRODUCTION: THEMES IN ?...

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Unformatted text preview: CHAPTER 1 } INTRODUCTION: THEMES IN ? THE STUDY OF LIFE OUTLINE l I . Life’s Hierarchical Order A. The living world is a hierarchy, with each level of biological structure building on P the level below it Each level of biological structure has emergent properties Cells are an organism’s basic units of structure and function . The continuity of life is based on heritable information in the form of DNA Structure and function are correlated at all levels of biological organization Organisms are open systems that interact continuously with their environments owweow . Regulatory mechanisms ensure a dynamic balance in living systems 11. Ev lution, Unity, and Diversity A. Diversity and unity are the dual faces of life on Earth B. Evolution is the core theme of biology III. Science as a Process A. Testable hypotheses are the hallmarks of the scientific process B. Science and technology are functions of society C. Biology is a multidisciplinary adventure OBJECTIVES After reading this chapter and attending lecture, the student should be able to: 1. Briefly describe unifying themes that pervade the science of biology. 2. Diagram the hierarchy of structural levels in biology. 3. Explain how the properties of life emerge from complex organization. 4. Describe seven emergent properties associated with life. 5. Distinguish between holism and reductionism. 6. Explain how technological breakthroughs contributed to the formulation of the cell theory and our current knowledge of the cell. 7. Distinguish between prokaryotic and eukaryotic cells. 8. Explain, in their own words, what is meant by "form fits function." 9. List the five kingdoms of life and distinguish among them. 10. Briefly describe how Charles Darwin's ideas contributed to the conceptual framework of biology. ll. Outline the scientific method. 12. Distinguish between inductive and deductive reasoning. 13. Explain how science and technology are interdependent. 2 Chapter 1 Introduction: Themes in the Study of Life KEY TERMS emergent property holism evolution control group population reductionism natural selection variable community prokaryotic scientific method experimental group ecosystem eukaryotic hypothesis deductive reasoning biome taxonomy inductive reasoning scientific theory biogenesis LECTURE NOTES Biology, the study of life, is a human endeavor resulting from an innate attraction to life in its divers e forms (E.O. Wilson's biophilia). The science of biology is enormous in scope. Asas It reaches across size scales from submicroscopic molecules to the global distribution of biological communities. It encompasses life over huge spans of time from contemporary organisms to ancestral life forms stretching back nearly four billion years. cience, biology is an ongoing process. As a result of new research methods developed over the past few decades, there has been an information explosion. Technological advances yield new information that may change the conceptual framework accepted by the majority of biologists. With rapid information flow and new discoveries, biology is in a continuous state of flux. There are, however, enduring unifying themes that pervade the science of biology: I. A hierarchy of organization The cellular basis of life Heritable information The correlation between structure and function The interaction of organisms with their environment Unity in diversity Evolution: the core theme Scientific process: the hypothetico-deductive method Life’s Hierarchical Order A. The living world is a hierarchy, with each level of biological structure building on the level below it A characteristic of life is a high degree of order. Biological organization is based on a hierarchy of structural levels, with each level building on the levels below it. Chapter 1 Introduction: Themes in the Study of Life 3 Atoms l Complex bioloiical molecules Subcellular organelles are ordered into Cells ¢ln multicellular organisms similar cells are organised into Tissues l Organs l Organ systems l Complex organism There are levels of organization beyond the individual organism: Population = Localized group of organisms belonging t to the same species Community = Populations of species living in the same ¢ area Ecosystem = An energy-processing system of community interactions that include abiotic environmental factors such as soil and water BiomeS = Large scale communities classified by predominant vegetation type and L distinctive combinations of plants and animals Biosphere = The sum of all the planet's ecosystems B. Each level of biological organization has emergent properties Emergent property = Property that emerges as a result of interactions between components. - With each step upward in the biological hierarchy, new properties emerge that were not present at the simpler organizational levels. - Life is difficult to define because it ‘is associated with numerous emergent properties that reflect a hierarchy of structural organization. Some of the emergent properties and processes associated with life are the following: 1. Order. Organisms are highly ordered, and other characteristics of life emerge from this complex organization. Chapter 1 Introduction: Themes in the Study of Life 3 Atoms l Complex bioloiical molecules Subcellular organelles ¢are ordered into Cells tin multicellular organisms similar cells are organised into Tissues l Organs l Organ systems i Complex organism There are levels of organization beyond the individual organism: Population = Localized group of organisms belonging {I to the same species Community = Populations of species living in the same area Ecosystem = An energy-processing system of community interactions that include abiotic environmental factors such as soil and water Biomes = Large scale communities classified by predominant vegetation type and t distinctive combinations of plants and animals Blosphere = The sum of all the planet's ecosystems B. Each level of biological organization has emergent properties Emergent property = Property that emerges as a result of interactions between components. - With each step upward in the biological hierarchy, new properties emerge that were not present at the simpler organizational levels. - Life is difficult to define because it is associated with numerous emergent properties that reflect a hierarchy of structural organization. Some of the emergent properties and processes associated with life are the following: 1. Order. Organisms are highly ordered, and other characteristics of life emerge from this complex organization. 4 Chapter 1 Introduction: Themes in the Study of Life 2. Reproduction. Organisms reproduce; life comes only from life (biogenesis). 3. Growth and Development. Heritable programs stored in DNA direct the species—specific pattern of growth and development. 4. Energy Utilization. Organisms take in and transform energy to do work, including the maintenance of their ordered state. 5. Response to Environment. Organisms respond to stimuli from their environment. 6. Homeostasis. Organisms regulate their internal environment to maintain a steady-state, even in the face of a fluctuating external environment. 7. Evolutionary Adaptation. Life evolves in response to interactions between organisms and their environment. Because properties of life emerge from complex organization, it is impossible to fully explain a higher level of order by breaking it into its parts. Holism = The principle that a higher level of order cannot be meaningfully explained by examining component parts in isolation. - An organism is a living whole greater than the sum of its parts. - For example, a cell dismantled to its chemical ingredients is no longer a cell. It is also difficult to analyze a complex process without taking it apart. Reductionism = The principle that a complex system can be understood by studying its component parts. ' Has been a powerful strategy in biology - Example: Watson and Crick deduced the role of DNA in inheritance by studying its molecular structure. The study of biology balances the reductionist strategy with the goal of understanding how the parts of cells, organisms, and populations are functionally integrated. C. Cells are an organism’s basic units of structure and function The cell is an organism’s basic unit of structure and function. - Lowest level of structure capable of performing all activities of life. - A11 organisms are composed of cells. - May exist singly as unicellular organisms or as subunits of multicellular organisms. The invention of the microscope led to the discovery of the cell and the formulation of the cell theory. - Robert Hooke (1665) reported a description of his microscopic examination of cork. Hooke described tiny boxes which he called "cells" (really cell walls). The significance of this discovery was not recognized until 150 years later. - Antonie van Leeuwenhok (1600's) used the microscope to observe living organisms such as microorganisms in pond water, blood cells, and animal sperm cells. - Matthias Schleiden and Theodor Schwann (1839) reasoned from their own microscopic studies and those of others, that all living things are made of cells. This formed the basis for the cell theory. ' The cell theory has since been modified to include the idea that all cells come from preexisting cells. Over the past 40 years, use of the electron microscope has-revealed the complex ultrastructure of cells. - Cells are bounded by plasma membranes that regulate passage of materials between the cell and its surroundings. - All cells, at some stage, contain DNA. Chapter 1 Introduction: Themes in the Study of Life 5 Based on structural organization, there are two major kinds of cells: prokaryotic and eukaryotic. Prokaryotic cell = Cell lacking membrane-bound organelles and a membrane—enclosed nucleus. - Found only in the archaebacteria and bacteria - Generally much smaller than eukaryotic cells - Contains DNA that is not separated from the rest of the cell, as there is no membrane-bound nucleus - Lacks membrane-bound organelles - Almost all have tough external walls Eukaryotic cell = Cell with a membrane-enclosed nucleus and membrane-enclosed organelles. - Found in protists, plants, fungi, and animals - Subdivided by internal membranes into different functional compartments called organelles 0 Contains DNA that is segregated from the rest of the cell. DNA is organized with proteins into chromosomes that are located within the nucleus, the largest organelle of most cells. - Cytoplasm surrounds the nucleus and contains various organelles of different functions - Some cells have a tough cell wall outside the plasma membrane (e.g., plant cells). Animal cells lack cell walls. Though structurally different, eukaryotic and prokaryotic cells have many similarities, especially in their chemical processes. D. The continuity of life is based on heritable information in the form of DNA Biological instructions for an organism's complex structure and function are encoded in DNA. 0 Each DNA molecule is made of four types of chemical building blocks called nucleotides. - The linear sequence of these four nucleotides encode the precise information in a gene, the unit of inheritance from parent to offspring. - An organism's complex structural organization is specified by an enormous amount of coded information. Inheritance is based on: ' A complex mechanism for copying DNA. - Passing the information encoded in DNA from parent to offspring. All forms of life use essentially the same genetic code. 0 A particular nucleotide sequence provides the same information to one organism as it does to another. - Differences among organisms reflect differences in nucleotide sequence. E. Structure and function are correlated at all levels of biological organization There is a relationship between an organism's structure and how it works. Form fits function. 0 Biological structure gives clues about what it does and how it works. - Knowing a structure's function gives insights about its construction. 0 This correlation is apparent at many levels of biological organization. Chapter 1 Introduction: Themes in the Study of Life F. Organisms are open systems that interact continuously with their environments Organisms interact with their environment, which includes other organisms as well as abiotic factors. - Both organism and environment are affected by the interaction between them. - Ecosystem dynamics include two major processes: 1. Nutrient cycling 2. Energy flow (see Campbell, Figure 1.7) G. Regulatory mechanisms ensure a dynamic balance in living systems Regulation of biological processes is critical for maintaining the ordered state of life. Many biological processes are self-regulating; that is, the product of a process regulates that process (= feedback regulation; see Campbell, Figure 1.8). - Positive feedback speeds a process up - Negative feedback slows a process down Organisms and cells also use chemical mediators to help regulate processes. - The hormone insulin, for example, signals cells in vertebrate organisms to take up glucose. As a result, blood glucose levels go down. I - In certain forms of diabetes mellitus, insulin is deficient and cells do not take up glucose as they should, and as a result, blood glucose levels remain high. Evolution, Unity, and Diversity A. Diversity and unity are the dual faces of life on Earth Biological diversity is enormous. - Estimates of total diversity range from five million to over 30 million species. - About 1.5 million species have been identified and named, including approximately 260,000 plants, 50,000 vertebrates, and 750,000 insects. To make this diversity more comprehensible, biologists classify species into categories. Taxonomy = Branch of biology concerned with naming and classifying organisms. - Taxonomic groups are ranked into a hierarchy from the most to least inclusive category: domain, kingdom, phylum, class, order, family, genus, species. - A six-kingdom system recognizes two prokaryotic groups and divides the Monera into the Archaebacteria and Eubacteria. - The kingdoms of life recognized in the traditional five-kingdom system are Monera, Protista, Plantae, Fungi, and Animalia (see Campbell, Figure 1.10). There is unity in the diversity of life forms at the lower levels of organization. Unity of life forms is evident in: c A universal genetic code. - Similar metabolic pathways (e.g., glycolysis). 0 Similarities of cell structure (e.g., flagella of protozoans and mammalian sperm cells). B. Evolution is the core theme of biology Evolution is the one unifying biological theme. - Life evolves. Species change over time and their history can be described as a branching tree of life. 0 Species that are very similar share a common ancestor at a recent branch point on the phylogenetic tree. - Less closely related organisms share a more ancient common ancestor. Chapter 1 Introduction: Themes in the Study of Life 7 ° All life is connected and can be traced back to primeval prokaryotes that existed more than three billion years ago. In 1859, Charles Darwin published 0n the Origin of Species in which he made two major points: 1. Species change, and contemporary species arose from a succession of ancestors through a process of "descent with modification." 2. A mechanism of evolutionary change is natural selection. Darwin synthesized the concept of natural selection based upon the following observations: - Individuals in a population of any species vary in many inheritable traits. ' Populations have the potential to produce more offspring than will survive or than the environment can support. - Individuals with traits best suited to the environment leave a larger number of offspring, which increases the proportion of inheritable variations in the next generation. This differential reproductive success is what Darwin called natural selection. Organisms’ adaptations to their environments are the products of natural selection. - Natural selection does not create adaptations; it merely increases the frequency of inherited variants that arise by chance. - Adaptations are the result of the editing process of natural selection. When exposed to specific environmental pressures, certain inheritable variations favor the reproductive success of some individuals over others. Darwin proposed that cumulative changes in a population over long time spans could produce a new species from an ancestral one. Descent with modification accounts for both the unity and diversity of life. - Similarities between two species may be a reflection of their descent from a common ancestor. - Differences between species may be the result of natural selection modifying the ancestral equipment in different environmental contexts. Science as a Process A. Testable hypotheses are the hallmarks of the scientific process As the science of life, biology has the characteristics associated with science in general. Science is a way of knowing. It is a human endeavor that emerges from our curiosity about ourselves, the world, and the universe. Good scientists are people who: 0 Ask questions about nature and believe those questions are answerable. - Are curious, observant, and passionate in their quest for discovery. - Are creative, imaginative, and intuitive. - Are generally skeptics. Scientific method = Process which outlines a series of steps used to answer questions. - Is not a rigid procedure. - Based on the conviction that natural phenomena have natural causes. - Requires evidence to logically solve problems. The key ingredient of the scientific process is the- hypothetico-deductive method, which is an approach to problem-solving that involves: 1. Asking a question and formulating a tentative answer or hypothesis by inductive reasoning. 2. Using deductive reasoning to make predictions from the hypothesis and then testing the validity of those predictions. 8 Chapter 1 Introduction: Themes in the Study of Life Hypothesis = Educated guess proposed as a tentative answer to a specific question or problem. Inductive reasoning = Making an inference from a set of specific observations to reach a general conclusion. Deductive reasoning = Making an inference from general premises to specific consequences, which logically follow if the premises are true. - Usually takes the form of If..then logic. - In science, deductive reasoning usually involves predicting experimental results that are expected if the hypothesis is true. Some students cannot make the distinction between inductive and deductive reasoning. An effective teaching strategy is to let them actually experience both processes. To illustrate inductive reasoning, provide an every day scenario with enough pieces of information for student to hypothesize a plausible explanation for some event. Demonstrate deductive reasoning by asking students to solve a simple problem, based upon given assumptions. Useful hypotheses have the following characteristics: ' Hypotheses are possible causes. Generalizations formed by induction are not necessarily hypotheses. Hypotheses should also be tentative explanations for observations or solutions to problems. - Hypotheses reflect past experience with similar questions. Hypotheses are not just blind propositions, but are educated guesses based upon available evidence. - Multiple hypotheses should be proposed whenever possible. The disadvantage of operating under only one hypothesis is that it might restrict the search for evidence in support of this hypothesis; scientists might bias their search, as well as neglect to consider other possible solutions. ' Hypotheses must be testable via the hypothetico-deductive method. Predictions made from hypotheses must be testable by making observations or performing experiments. This limits the scope of questions that science can answer. - Hypotheses can be eliminated, but not confirmed with absolute certainty. If repeated experiments consistently disprove the predictions, then we can assume that the hypothesis is false. However, if repeated experimentation supports the deductions, we can only assume that the hypothesis may be true; accurate predictions can be made from false hypotheses. The more deductions that are tested and supported, the more confident we can be that the hypothesis is true. Another feature of the scientific process is the controlled experiment which includes control and experimental groups. Control group = In a controlled experiment, the group in which all variables are held constant. 0 Controls are a necessary basis for comparison with the experimental group, which has been exposed to a single treatment variable. - Allows conclusions to be made about the effect of experimental manipulation. - Setting up the best controls is a key element of good experimental design. Variable = Condition of an experiment that is subject to change and that may influence an experiment’s outcome. Experimental group = In a controlled experiment, the group in which one factor or treatment is varied. - Science is an ongoing process that is a self-correcting way of knowing. Scientists: ' Build on prior scientific knowledge. - Try to replicate the observations and experiments of others to check on their conclusions. Chapter 1 Introduction: Themes in the Study of Life 9 Share information through publications, seminars, meetings, and personal communication. Hypothesis 1 Test = experiment [—v or observations ——l support. Reject hypothesus hypothesis (max be true) Reject L l L Test repeatedly Modify or abandon hypothesis 1 Accept. Verify i Hypothesis becomes theory What really advances science is not just an accumulation of facts, but a new concept that collectively explains observations that previously seemed to be unrelated. Newton, Darwin, and Einstein stand out in the history of science because they synthesized ideas with great explanatory power. Scientific theories are comprehensive conceptual frameworks which are well supported by evidence and are widely accepted by the scientific community. B. Science and technology are functions of society Science and technology are interdependent. Technology extends our ability to observe and measure, which enables scientists to work on new questions that were previously unapproachable. Science, in turn, generates new information that makes technological inventions possible. Example: Watson and Crick's scientific discovery of DNA structure led to further investigation that enhanced our understanding of DNA, the genetic code, and how to transplant foreign genes into microorganisms. The biotechnology industry has capitalized on this knowledge to produce valuable pharmaceutical products such as human insulin. We have a love-hate relationship with technology. Technology has improved our standard of living. The consequence of using technology also includes the creation of new problems such as increased population growth, acid rain, deforestation, global warming, nuclear accidents, ozone holes, ‘toxic wastes, and endangered species. Solutions to these problems have as much to do with politics, economics, culture and values as with science and technology. A better understanding of nature must remain the goal of science. Scientists should: Try to influence how technology is used. Help educate the public about the benefits and hazards of specific technologies. 10 Chapter 1 Introduction: Themes in the Study of Life C. Biology is a multidisciplinary adventure Biology is a multidisciplinary science that integrates concepts from chemistry, physics and mathematics. Biology also embraces aspects of humanities and the social sciences. REFERENCES Campbell, N. Biology. 5th ed. Menlo Park, California: Benjamin/Cummings, 1998. Moore, J.A. "Science as a Way of Knowing—Evolutionary Biology." American Zoologist, 24(2): 470-475, 1980. ...
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apLectureNotes01 - CHAPTER 1 } INTRODUCTION: THEMES IN ?...

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