 Concepts & Methods in Biology Chapter 1

Biology Scientific study of life Lays the foundation for asking basic questions about life and the natural world

Why Study Biology? To learn how organisms are constructed, how they function, where they live, and what they do To learn how organisms are constructed, how they function, where they live, and what they do To help develop, modify, and refine ideas about life To help develop, modify, and refine ideas about life

Molecules of Life All things are made up of the same units of matter All things are made up of the same units of matter Living things are made up of a certain subset of molecules: Living things are made up of a certain subset of molecules: Nucleic acids Nucleic acids Proteins Proteins Carbohydrates Carbohydrates Lipids Lipids

DNA (deoxyribonucleic acid) Signature molecule of life Signature molecule of life Molecule of inheritance Molecule of inheritance Directs assembly of amino acids Directs assembly of amino acids

DNA and Inheritance Inheritance Inheritance Acquisition of traits by way of transmission of DNA from parent to offspring Acquisition of traits by way of transmission of DNA from parent to offspring Reproduction Reproduction Mechanism by which an organism produces offspring Mechanism by which an organism produces offspring Governed by instructions in DNA Governed by instructions in DNA

DNA Guides Development Multicelled organisms develop Multicelled organisms develop Series of stages Series of stages Instructions for each stage in DNA Instructions for each stage in DNA

Nothing Lives without Energy Energy = Capacity to do work Metabolism = Reactions by which cells acquire and use energy to grow, survive, and reproduce

Sensing and Responding Organisms sense changes in their environment and make responses to them Organisms sense changes in their environment and make responses to them Receptors detect specific forms of energy (stimuli) Receptors detect specific forms of energy (stimuli) Allows maintenance of homeostasis Allows maintenance of homeostasis

Levels of Organization Cell Multicelled Organism PopulationCommunityEcosystemBiosphere

Interdependencies among Organisms Producers Make their own food Consumers Depend on energy stored in tissues of producers Decomposers Break down remains and wastes

Energy Flow Usually starts with energy from sun Usually starts with energy from sun Transfer from one organism to another Transfer from one organism to another Energy flows in one direction Energy flows in one direction Eventually, all energy flows back to the environment Eventually, all energy flows back to the environment

Producers Consumers, Decomposers NUTRIENT CYCLING ONE-WAY FLOW OF ENERGY In time, all energy flows back to the environment. ENERGY FROM SUN

Unity of Life All organisms: Are composed of the same substances Are composed of the same substances Engage in metabolism Engage in metabolism Sense and respond to the environment Sense and respond to the environment Have the capacity to reproduce based on instructions in DNA Have the capacity to reproduce based on instructions in DNA

Diversity of Life Millions of living species Millions of living species Millions more now extinct Millions more now extinct Classification schemes attempt to organize diversity Classification schemes attempt to organize diversity

Scientific Names Devised by Carolus Linnaeus Devised by Carolus Linnaeus First name is genus (plural, genera) First name is genus (plural, genera) Homo sapiens - genus is Homo Homo sapiens - genus is Homo Second name is species within genus Second name is species within genus

Eubacteria (Bacteria) Archaebacteria (Archaea) Eukaryota (Eukaryotes) 3 Domains

Origin of life Eubacteria Archaebacteria Eukaryotes ProtistansPlantsFungiAnimals 6 Kingdoms

Single cells Single cells No nucleus or organelles No nucleus or organelles Smaller, less complex Smaller, less complex Prokaryotic Organisms Eukaryotic Organisms Single- or multi-celled Single- or multi-celled Nucleus and other organelles Nucleus and other organelles Larger, more complex Larger, more complex

Mutation: Source of Variation Mutation = change in structure of DNA Mutation = change in structure of DNA Basis for the variation in heritable traits Basis for the variation in heritable traits Most are harmful Most are harmful

Adaptive Trait A trait that gives the individual an advantage in survival or reproduction, under a given set of circumstances

Evolution Genetically based change in a line of descent over time Genetically based change in a line of descent over time Population changes, not individuals Population changes, not individuals

Artificial Selection Breeders are selective agents Breeders are selective agents Individuals exhibiting favored traits are bred Individuals exhibiting favored traits are bred Favored traits become more common in population Favored traits become more common in population

Natural Selection Individuals vary in some heritable traits Individuals vary in some heritable traits Some forms of heritable traits are more adaptive Some forms of heritable traits are more adaptive Natural selection is differences in survival and reproduction among individuals that vary in their traits Natural selection is differences in survival and reproduction among individuals that vary in their traits Adaptive forms of traits become more common than other forms Adaptive forms of traits become more common than other forms

Antibiotic Resistance Antibiotics are used to kill bacteria Antibiotics are used to kill bacteria Mutations for antibiotic resistance exist or arise Mutations for antibiotic resistance exist or arise Antibiotic-resistant bacteria survive and reproduce better than nonresistant Antibiotic-resistant bacteria survive and reproduce better than nonresistant Over time, proportion of antibiotic-resistant bacteria increases Over time, proportion of antibiotic-resistant bacteria increases

Scientific Method Observe phenomenon Observe phenomenon Develop hypotheses Develop hypotheses Make predictions Make predictions Devise test of predictions Devise test of predictions Carry out test and analyze results Carry out test and analyze results

Inductive Logic Using observations and facts to arrive at generalizations or hypotheses Using observations and facts to arrive at generalizations or hypotheses Observation: Eagles, swallows, and robins have feathers Observation: Eagles, swallows, and robins have feathers Hypothesis: All birds have feathers Hypothesis: All birds have feathers

Deductive Logic Drawing a specific conclusion based on a generalization Drawing a specific conclusion based on a generalization Generalization - Birds have feathers Generalization - Birds have feathers Example - Eagles are birds Example - Eagles are birds Conclusion - Eagles have feathers Conclusion - Eagles have feathers

Role of Experiments Used to study a phenomenon under known conditions Used to study a phenomenon under known conditions Allows you to predict what will happen if a hypothesis is not wrong Allows you to predict what will happen if a hypothesis is not wrong Can never prove a hypothesis 100% correct Can never prove a hypothesis 100% correct

Experimental Design Control group Control group A standard for comparison A standard for comparison Identical to experimental group except for variable being studied Identical to experimental group except for variable being studied Sampling error Sampling error Nonrepresentative sample skews results Nonrepresentative sample skews results Minimize by using large samples Minimize by using large samples

Scientific Theory A hypothesis that has been tested for its predictive power many times and has not yet been found incorrect A hypothesis that has been tested for its predictive power many times and has not yet been found incorrect Has wide-ranging explanatory power Has wide-ranging explanatory power Darwin’s theory of evolution by natural selection Darwin’s theory of evolution by natural selection

Limits of Science Scientific approach cannot provide answers to subjective questions Scientific approach cannot provide answers to subjective questions Cannot provide moral, aesthetic, or philosophical standards Cannot provide moral, aesthetic, or philosophical standards Conflict with supernatural beliefs Conflict with supernatural beliefs Copernicus Copernicus Darwin Darwin

Scientists Raise Questions The external world, not internal conviction, must be the testing ground for scientific beliefs