Module 1: What is biology?Module 1: What is biology?

What is Science?What is Science? Latin scientia = knowledgeLatin scientia = knowledge

A systematic enterprise that builds A systematic enterprise that builds and organizes knowledge in the form and organizes knowledge in the form of testable explanations and of testable explanations and predictions about the universe. predictions about the universe.

Science is a processScience is a process Scientific MethodScientific Method

BiologyBiology is the study of is the study of livingliving things.things. Bio = lifeBio = life -logy = study of-logy = study of

The Organization of LifeThe Organization of Life Living things function and interact with each Living things function and interact with each

other on many levels.other on many levels.

The organization of life is a The organization of life is a hierarchyhierarchy of of levels of increasing complexity.levels of increasing complexity. CellularCellular OrganismalOrganismal PopulationalPopulational

Levels of organization: Levels of organization: cellular levelcellular level

Levels of organization: Levels of organization: organismal organismal levellevel

Levels of organization: Levels of organization: populational populational levellevel

The Diversity of LifeThe Diversity of Life Living things are Living things are

diverse.diverse. Therefore, we divide Therefore, we divide

them into groups:them into groups:

sapienssapiensHomoHomoHominidaeHominidaePrimatesPrimatesMammaliaMammaliaChordataChordataAnimaliaAnimaliaEukaryaEukarya

Biology HierarchyBiology Hierarchy DomainDomain KingdomKingdom PhylumPhylum ClassClass OrderOrder FamilyFamily Genus Genus SpeciesSpecies

Properties of LifeProperties of Life CellsCells OrganizationOrganization MetabolismMetabolism HomeostasisHomeostasis GrowthGrowth ReproductionReproduction Responsiveness Responsiveness HeredityHeredity

Properties of LifeProperties of Life: : CellsCells All living things are All living things are

comprised of comprised of at leastat least one cell.one cell.

Properties of LifeProperties of Life: : OrganizationOrganization Both molecular and cellular organization.Both molecular and cellular organization. Living things must be able to organize simple Living things must be able to organize simple

substances into complex ones.substances into complex ones.

Properties of LifeProperties of Life: : MetabolismMetabolism Living things take in energy and use it for Living things take in energy and use it for

maintenance and growth. maintenance and growth. Metabolism = All chemical reactions in an Metabolism = All chemical reactions in an

organismorganism

Properties of LifeProperties of Life: : HomeostasisHomeostasis

Maintaining a stable state of conditionsMaintaining a stable state of conditions Body temperatureBody temperature Blood volumeBlood volume pH balancepH balance Water balanceWater balance

Properties of LifeProperties of Life: : GrowthGrowth Cell division - the orderly formation of new cells.Cell division - the orderly formation of new cells. Cell enlargement - the increase in size of a cell. Cells grow Cell enlargement - the increase in size of a cell. Cells grow

to a certain size and then divide.to a certain size and then divide. An organism gets larger as the number of its cells increases.An organism gets larger as the number of its cells increases.

Properties of LifeProperties of Life: : ReproductionReproduction Reproduction is not Reproduction is not

essential for the survival essential for the survival of individual organisms, of individual organisms, but must occur for a but must occur for a species to survive.species to survive.

Properties of LifeProperties of Life: : ResponsivenessResponsiveness

Living things will make changes in response to Living things will make changes in response to a stimulus in their environment.a stimulus in their environment. LightLight TemperatureTemperature GravityGravity OdorOdor SoundSound Water Water

Properties of LifeProperties of Life: : HeredityHeredity Traits are passed on to Traits are passed on to

the next generation in the next generation in Nucleic Acid.Nucleic Acid.

Properties of LifeProperties of Life Is a virus alive?Is a virus alive?

CellsCells OrganizationOrganization MetabolismMetabolism HomeostasisHomeostasis GrowthGrowth ReproductionReproduction Responsiveness Responsiveness HeredityHeredity

Properties of LifeProperties of Life Is a machine alive?Is a machine alive?

CellsCells OrganizationOrganization MetabolismMetabolism HomeostasisHomeostasis GrowthGrowth ReproductionReproduction Responsiveness Responsiveness HeredityHeredity

Properties of LifeProperties of Life Is a city alive?Is a city alive?

CellsCells OrganizationOrganization MetabolismMetabolism HomeostasisHomeostasis GrowthGrowth ReproductionReproduction Responsiveness Responsiveness HeredityHeredity

The Scientific MethodThe Scientific Method

Stages of a Scientific InvestigationStages of a Scientific Investigation Biology is a dynamic science with new ideas Biology is a dynamic science with new ideas

appearing and replacing old ones.appearing and replacing old ones.

Scientific MethodScientific Method ObservationObservation

Senses / Lit searchSenses / Lit search HypothesisHypothesis

Testable and RepeatableTestable and Repeatable Null hypothesis – No significant differenceNull hypothesis – No significant difference Alternative hypothesis – significant differenceAlternative hypothesis – significant difference

PredictionPrediction If a hypothesis is correct, then specific consequences can be expectedIf a hypothesis is correct, then specific consequences can be expected

ExperimentExperiment Sample Size = 30Sample Size = 30 Control, change one variableControl, change one variable

Analysis of ResultsAnalysis of Results Quantitative (Statistical testing)Quantitative (Statistical testing)

ConclusionConclusion

Scientific MethodScientific Method ControlControl

Parallel design to Parallel design to minimize effect of minimize effect of variables other than variables other than the independent the independent variable being tested. variable being tested.

PlaceboPlacebo ““Blind study”Blind study”

Louis PasteurLouis Pasteur Experimentation Experimentation

disproved the widely-disproved the widely-held notion that life held notion that life could arise from nothingcould arise from nothing

19th century France19th century France

Observation: Observation: Question: Question:

Hypothesis: Hypothesis: Experiment: Experiment:

Collect results: Collect results: Conclusion:Conclusion:

Broth contaminated with microbesBroth contaminated with microbes

Do microbes spontaneously appear?Do microbes spontaneously appear?Microbes come from the airMicrobes come from the air

Louis PasteurLouis Pasteur

Louis PasteurLouis Pasteur

Observation: Observation: Question: Question:

Hypothesis: Hypothesis: Experiment: Experiment:

Collect results: Collect results: Conclusion:Conclusion:

Broth contaminated with microbesBroth contaminated with microbes

Do microbes spontaneously appear?Do microbes spontaneously appear?Microbes come from the airMicrobes come from the air

Louis PasteurLouis Pasteur

Broth left exposed or unexposedBroth left exposed or unexposed

S-neck flask remains sterileS-neck flask remains sterileMicrobes come from the air. Life does Microbes come from the air. Life does

not arise from nothing.not arise from nothing.

Correlation v Causation

A correlation between two variables does not A correlation between two variables does not necessarily imply that one causes the other.necessarily imply that one causes the other.

Are Mexican lemons making our roads safer?

Is Internet Explorer responsible for murder?

Theory and CertaintyTheory and Certainty The term “The term “theorytheory” means different things to ” means different things to

different audiencesdifferent audiences

To scientistsTo scientists A theory represents certainty and is a unifying A theory represents certainty and is a unifying

explanation for a broad range of observations.explanation for a broad range of observations.

To the general publicTo the general public A theory implies a lack of knowledge or guess.A theory implies a lack of knowledge or guess.

Theory and CertaintyTheory and Certainty A Theory is a complicated result of many separate A Theory is a complicated result of many separate

experiments that all suggest a similar thing.experiments that all suggest a similar thing.

Scientists’ acceptance of theory is provisional.Scientists’ acceptance of theory is provisional. The possibility always remains that future evidence will The possibility always remains that future evidence will

cause a theory to be revised.cause a theory to be revised.

The process of science is not just trial-and-error but The process of science is not just trial-and-error but involves judgment and intuition.involves judgment and intuition.

Four Theories Unify Biology as a Four Theories Unify Biology as a ScienceScience

1. The Cell Theory1. The Cell Theory

2. The Gene Theory2. The Gene Theory

3. The Theory of Heredity3. The Theory of Heredity

4. The Theory of Evolution4. The Theory of Evolution

The Cell TheoryThe Cell Theory All organisms are All organisms are

composed of at least one composed of at least one cell.cell.

The cell is the most basic The cell is the most basic unit of life.unit of life.

All cells come from pre-All cells come from pre-existing cells.existing cells.

The Gene TheoryThe Gene Theory Genetic information is encoded in molecules of Genetic information is encoded in molecules of

deoxyribonucleic acid (DNA).deoxyribonucleic acid (DNA).

Genes encode specific proteins or RNA or act to Genes encode specific proteins or RNA or act to regulate other genes.regulate other genes.

The proteins and RNA encoded by an organism’s The proteins and RNA encoded by an organism’s genes determine what it will be like in terms of form genes determine what it will be like in terms of form and function.and function.

The Theory of HeredityThe Theory of Heredity Genes are passed down from generation to Genes are passed down from generation to

generation.generation.

Mendel’s theory of heredity gave rise to the field Mendel’s theory of heredity gave rise to the field of genetics.of genetics.

Chromosomal theory of inheritance located Chromosomal theory of inheritance located Mendelian genes on chromosomes.Mendelian genes on chromosomes.

The Theory of EvolutionThe Theory of Evolution All living organisms are related to one another All living organisms are related to one another

in a common tree of descent.in a common tree of descent.

Charles Darwin’s theory of evolution explains Charles Darwin’s theory of evolution explains the unity and diversity of life as “descent with the unity and diversity of life as “descent with modification.”modification.” Scientists have been able to identify changes in Scientists have been able to identify changes in

individual genes that are responsible for individual genes that are responsible for differences among individuals.differences among individuals.

EvolutionEvolution