CHAPTER

1INTRODUCTION: THEMES INTHE STUDY OF LIFEOUTLINEI.Life’s Hierarchical OrderA.The living world is a hierarchy, with each level of biological structure building onthe level below itB.Each level of biological structure has emergent propertiesC.Cells are an organism’s basic units of structure and functionD.

The continuity of life is based on heritable information in the form of DNAE.Structure and function are correlated at all levels of biological organizationF.Organisms are open systems that interact continuously with their environmentsG.Regulatory mechanisms ensure a dynamic balance in living systemsII.Evolution, Unity, and DiversityA.Diversity and unity are the dual faces of life on EarthB.Evolution is the core theme of biology

III.Science as a ProcessA.Testable hypotheses are the hallmarks of the scientific processB.Science and technology are functions of societyC.Biology is a multidisciplinary adventureOBJECTIVESAfter 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 thecell 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 ofbiology.11.Outline the scientific method.12.Distinguish between inductive and deductive reasoning.13.Explain how science and technology are interdependent.2

Chapter 1Introduction: Themes in the Study of LifeKEY TERMSemergent propertyholismevolutioncontrol grouppopulationreductionismnatural selectionvariablecommunityprokaryoticscientific methodexperimental groupecosystemeukaryotichypothesisdeductive reasoning

biometaxonomyinductive reasoningscientific theorybiogenesisLECTURE NOTESBiology, the study of life, is a human endeavor resulting from an innate attraction to life in itsdiverse forms (E.O. Wilson's biophilia).The science of biology is enormous in scope.•It reaches across size scales from submicroscopic molecules to the global distribution ofbiological communities.•

It encompasses life over huge spans of time from contemporary organisms to ancestrallife forms stretching back nearly four billion years.As a science, biology is an ongoing process.•As a result of new research methods developed over the past few decades, there has beenan information explosion.•Technological advances yield new information that may

change the conceptualframework accepted by the majority of biologists.With rapid information flow and new discoveries, biology is in a continuous state of flux. Thereare, however, enduring unifying themes that pervade the science of biology:•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 methodI.Life’s Hierarchical OrderA.The living world is a hierarchy, with each level of biological structurebuilding on the level below itA 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 1Introduction: Themes in the Study of Life3are ordered intoIn multicellular organisms similar cells are organised intoLarge scale communities classified bypredominant vegetation type anddistinctive combinations of plants andanimalsThe sum of all the planet's ecosystemsAtomsComplex biological moleculesSubcellular organellesCellsTissues

OrgansOrgan systemsComplex organismThere are levels of organization beyond the individual organism:Population=Community=Ecosystem=Biomes=Biosphere=B.Each level of biological organization has emergent propertiesEmergent property

= Property that emerges as a result of interactions betweencomponents.•With each step upward in the biological hierarchy, new properties emerge thatwere not present at the simpler organizational levels.•Life is difficult to define because it is associated with

numerous emergentproperties 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 emergefrom this complex organization.An energy-processing system ofcommunity interactions that includeabiotic environmental factors such assoil and waterPopulations of species living in the samearea

Localized group of organisms belongingto the same species4Chapter 1Introduction: Themes in the Study of Life2.Reproduction.Organisms reproduce; life comes only from life (biogenesis).3.Growth and Development.Heritable programs

stored in DNA direct thespecies-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 theirenvironment.6.Homeostasis.Organisms regulate their internal environment

to maintain asteady-state, even in the face of a fluctuating external environment.7.Evolutionary Adaptation.Life evolves in response to interactions betweenorganisms 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 explainedby 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 itscomponent parts.•

Has been a powerful strategy in biology•Example: Watson and Crick deduced the role of DNA in inheritance bystudying 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 functionThe cell is an organism's basic unit of structure and function.•Lowest level of structure capable of performing all activities of life.•All organisms are composed of cells.•May exist singly as unicellular organisms

or as subunits of multicellularorganisms.The invention of the microscope led to the discovery of the cell and the formulationof the cell theory.•Robert Hooke (1665) reported a description of his microscopic examination ofcork. Hooke described tiny boxes which he called "cells" (really cell walls). Thesignificance of this discovery was not recognized until 150 years later.•

Antonie van Leeuwenhok (1600's) used the microscope to observe livingorganisms such as microorganisms in pond water, blood cells, and animal spermcells.•Matthias Schleiden and Theodor Schwann (1839) reasoned

from their ownmicroscopic 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 comefrom preexisting cells.Over the past 40 years, use of the electron microscope has revealed the complexultrastructure of cells.•Cells are bounded by

plasma membranesthat regulate passage of materialsbetween the cell and its surroundings.•All cells, at some stage, contain DNA.Chapter 1Introduction: Themes in the Study of Life5Based on structural organization, there are two major kinds of cells: prokaryoticandeukaryotic.Prokaryotic cell

= Cell lacking membrane-bound organelles and a membrane-enclosednucleus.•Found only in the archaebacteria and bacteria•Generally much smaller than eukaryotic cells•Contains DNA that is notseparated from the rest of the cell, as there is nomembrane-bound nucleus•Lacks membrane-bound organelles•Almost all have tough external wallsEukaryotic 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 compartmentscalled organelles•Contains DNA that is segregated from the rest of the cell. DNA is organized

with proteins into chromosomesthat are located within the nucleus, the largestorganelle of most cells.•Cytoplasmsurrounds the nucleus and contains various organelles of differentfunctions•Some cells have a tough cell walloutside the plasma membrane (e.g., plantcells). 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 ofDNABiological instructions for an organism's complex structure and function are encoded inDNA.•Each DNA molecule is made of four types of chemical building blocks callednucleotides.•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 enormousamount 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.

•A particular nucleotide sequence provides the same information to oneorganism as it does to another.•Differences among organisms reflect differences in nucleotide sequence.E.Structure and function are correlated at all levels of biologicalorganization

There is a relationship between an organism's structure and how it works. Formfits function.•Biological structure gives clues about what it does and how it works.•Knowing a structure's function gives insights about its construction.•This correlation is apparent at many levels of biological organization.