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BIOLOGYBIOLOGY!!

biosbios = life= lifeologyology == study ofstudy of

The Study of LifeThe Study of Life

What is LIFE?What is LIFE?

What are some characteristics we associate with the “definition”life?

I know it when I see it!

What are the Properties of Life?What are the Properties of Life?

1.1. Precise organization (order)Precise organization (order)

2.2. Homeostasis Homeostasis

3.3. Response to the environmentResponse to the environment

4.4. Energy uptake and useEnergy uptake and use

5.5. Growth and developmentGrowth and development

6.6. ReproductionReproduction

7.7. Ability to EvolveAbility to Evolve

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1) Order

Properties of Life

Properties of Life2) Homeostasis

Properties of Life3) Response to

the Environment

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Properties of Life4) Energy Processing

Properties of Life5) Growth and Development

Properties of Life6) Reproduction

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Properties of Life

7) Evolution & Adaptation

Properties of Life?Properties of Life?

1.1. Precise organization (order)Precise organization (order)

2.2. Homeostasis Homeostasis

3.3. Response to the environmentResponse to the environment

4.4. Energy uptake and useEnergy uptake and use

5.5. Growth and developmentGrowth and development

6.6. ReproductionReproduction

7.7. Ability to EvolveAbility to Evolve

Is It Alive? Why or Why Not?Is It Alive? Why or Why Not?

Escherichia coliEscherichia coli bacteriabacteria

Cologne CathedralCologne Cathedral

Hoover DamHoover Dam

Baby ChickenBaby Chicken

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Biosphere Ecosystems

Levels of Organization:

Communities

Populations IndividualsOrgans or Organ

Systems

Levels of Organization:

Organs or Organ Systems

Organelles Molecules

Tissues Cells

Emergent PropertiesEmergent Properties

•Each level of the biological hierarchy is more than merely the sum of its parts

•Emergent properties result from interactions among components at each level

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Emergent PropertiesEmergent Properties .

Life itself is an emergent property

Cells are the simplest units of lifeCells are the simplest units of life.••The cell is the lowest level of structure that The cell is the lowest level of structure that has all of the properties or qualities we use to has all of the properties or qualities we use to define life.define life.

••Some organisms consist of a single cell, Some organisms consist of a single cell, others are others are multicellularmulticellular aggregates of aggregates of specialized cells.specialized cells.

““ Observation XVIII" of Observation XVIII" of the the MicrographiaMicrographia

HookeHooke ’’s s CompoundCompound MicroscopeMicroscope

The first cells were observed and named by The first cells were observed and named by Robert Hooke in 1665 from a slice of cork.Robert Hooke in 1665 from a slice of cork.

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Anton van Leewenhoek“No more pleasant site has met my eye than this!”

Van Leewenhoek`ssimple microscope

Anton van Leeuwenhoek, was the first to Anton van Leeuwenhoek, was the first to see singlesee single --celled organisms in pond water celled organisms in pond water

and observe cells in blood and sperm.and observe cells in blood and sperm.

Leeuwenhoek reported how in the plaque scraped from his teeth: "I then most always saw, with great wonder, that in the said matter there were many very little living animalcules, veryprettily a-moving. The biggest sort. . . had a very strong and swift motion, and shot through the spittle like a pike does through the water."

In the mouth an old man who had reportedly never cleaned his teeth in his life: "an unbelievably great company of living animalcules, a-swimming more nimbly than any I had ever seen up to this time.”

•• In 1839, In 1839, MatthaisMatthais SchleidenSchleiden and Theodor Schwann and Theodor Schwann extrapolated from their own microscopic research extrapolated from their own microscopic research and that of others to propose the and that of others to propose the cell theorycell theory ..

•• The cell theory postulates that cells are the basic unit of struThe cell theory postulates that cells are the basic unit of stru cture cture and physiology in all living things.and physiology in all living things.

•• One of the great paradigms of BiologyOne of the great paradigms of Biology ……

•• Cell Theory is to Biology as the Atomic Theory is t o PhysicsCell Theory is to Biology as the Atomic Theory is t o Physics

•• But... Thought cells formed spontaneouslyBut... Thought cells formed spontaneously …… in a manner similar to in a manner similar to crystal growthcrystal growth

• In 1855, Rudolf Virchow extended the cell In 1855, Rudolf Virchow extended the cell theory :theory :

• New cells are produced by the division of existing c ells.ew cells are produced by the division of existing c ells.

•• Critical process in reproduction, growth, and repai r of Critical process in reproduction, growth, and repai r of multicellularmulticellular organisms.organisms.

THE CELL THEORYTHE CELL THEORY

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•• All cells are enclosed by a membrane that All cells are enclosed by a membrane that regulates the passage of materials between the regulates the passage of materials between the cell and its surroundings.cell and its surroundings.

•• All cells contain DNA, the heritable material that All cells contain DNA, the heritable material that directs the celldirects the cell ’’s activities.s activities.

•• Two major kinds of cells Two major kinds of cells -- prokaryotic cells and prokaryotic cells and eukaryotic cells eukaryotic cells -- can be distinguished by their can be distinguished by their structural organization.structural organization.

•• The cells of the microorganisms called bacteria and The cells of the microorganisms called bacteria and archaeaarchaea are prokaryotic. Do not contain organelles.are prokaryotic. Do not contain organelles.

•• All other forms of life have the more complex All other forms of life have the more complex eukaryotic cells.eukaryotic cells.

•• Biological instructions for life are encoded Biological instructions for life are encoded in DNA (in DNA ( deoxyribonucleic aciddeoxyribonucleic acid ).).

•• DNA is the substance of genes.DNA is the substance of genes.

The continuity of life is based on heritable The continuity of life is based on heritable information in the form of DNAinformation in the form of DNA

•• The entire The entire ““ librarylibrary ”” of genetic instructions that an of genetic instructions that an organism inherits is called its genome.organism inherits is called its genome.

•• The genome of a human cell is 3 billion chemical The genome of a human cell is 3 billion chemical letters long.letters long.

•• The The ““ rough draftrough draft ”” of the sequence of nucleotides in the of the sequence of nucleotides in the human genome was published in 2001.human genome was published in 2001.

•• Biologists are learning the functions of Biologists are learning the functions of thousands of genes and how their activities are thousands of genes and how their activities are coordinated in the development of an organism.coordinated in the development of an organism.

Genomes (Human and Others)Genomes (Human and Others)

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Unity & DiversityUnity & Diversity

Diversity:• 1.5 million species described

• third million plant species• 50 000 vertebrates• almost 1 million insects

• Estimates 5-30 million species (10% described?)• Diversity decreasing as species go extinct.

Unity & DiversityUnity & Diversity

Taxonomy: classifying and organizing life

7) Unity & Diversity7) Unity & Diversity

Taxonomy: classifying and organizing life

species

Genus

Family

Order

Class

Phylum

Kingdom

Spaghetti

Good

For

Over

Came

Phillip

King

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GROUP NAME

ORGANISM

HUMANHUMAN CHIMPANZEECHIMPANZEE HOUSE CATHOUSE CAT LIONLION HOUSEFLYHOUSEFLY

KINGDOM Animalia Animalia Animalia Animalia Animalia

PHYLUM Chordate Chordate Chordate Chordate Arthropoda

CLASS Mammal Mammal Mammal Mammal Insect

ORDER Primates Primates Carnivora Carnivora Diptera

FAMILY Hominidae Pongidae Felidae Felidae Muscidae

GENUS Homo Pan Felis Panthera Musca

SPECIES sapiens troglodytes domestica leo domestica

Scientific Name Homo sapiens Pan troglodytes Felis domestica Felis leo Musca domestica

Examples from the Animal KingdomExamples from the Animal Kingdom

Unity & DiversityUnity & Diversity

• DOMAINS1. Bacteria2. Archea3. Eukarya

1. Plantae2. Animalia3. Fungi4. Protista

= Monera

Unity & DiversityUnity & Diversity

5 Kingdoms

1. Monera = Bacteria2. Plantae = Plants3. Animalia = Animals4. Fungi = Fungi5. Protista = Protists

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Unity & DiversityUnity & Diversity

Unity within diversity:• DNA as the common information molecule• Eukaryotes all share common cellular architecture

The Nature of Science The Nature of Science (& (& ““ thethe ”” scientific method)scientific method)

“Science is a process of inquiry that includes repeatable observationsand testable hypotheses.”

A) Discovery Science (Induction)

• Observations

• Data collection

• In field or lab!

B) Hypothetico-deductive model

• Scientific method

• Formal process

• Experimentation

• In field or lab!

• “How weird!... some of the frogs in this pond have 3 back legs! What the heck is going on here!?!?”

• Puzzling observation → Causal question

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• Causal Questions: Ask what is CAUSING a particular phenomenon or observation.

“What causes frog deformities?”

CAUSATIONis very different from

CORRELATION

• Causal question:

• “What is causing these frog deformities?”

• Possible explanations (hypotheses):

• Polluted water (e.g. herbicide runoff from fields)

• Infection by parasites

• Increased UV radiation

• CAUSATION does not equal CORRELATION

• Not all explanations are hypotheses

• Elves cast a spell on the frogs.

• God made them that way.

A possible explanation about what CAUSES something is a:

HYPOTHESIS!

Pollution is causes leg deformities in leopard frogs.

Prediction:

IF frog deformities are caused by polluted water,

THEN there should be more deformities in frogs raised experimentally in polluted water vs. those experimentally raised in clean water.

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Hypothesis

IF the hypothesis is TRUE,

THEN we can predict an outcome.

Predicted Outcome from a planned experiment

Actual Experiment

Test Data:% deformed frogs in

atrazine water = 0

% deformed frogs in pure water= 0

Compare!

Test: Evidence (data) derived from an actual experiment or observation that can be matched against predicted result.

Hypothesis: A testable explanation, a possible answer to a causal question

Conclusion: A decision about whether or not the evidence

supports the hypothesis.

Prediction: An expectation (derived from the hypothesis) about what you SHOULD see, if you were to do an experiment or make more observations.

Causal Question: Question about how or why things occur.

Science is a Cycle:Causal Question

Hypothesis

PredictionConclusion

Test (data)

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Label each statement: Causal question, hypothesis, prediction, test/data, and conclusion.

1. Trematode infection is probably responsible for frog deformities

2. What makes tadpoles produce frogs with extra legs?

3. The proportion of adult frogs with deformities should increase with increasing exposure to parasitic infections

4. I wonder if infection by trematodes could disrupt tadpole development?

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1. Conclusion

2. Causal Question

3. Prediction

4. Hypothesis

5. Test

10048

9032

7016

00

% of frogs w/ limb deformitiesDensity of trematodes (per tad)

New Hypothesis: Abnormal development of frogs is caused by a trematode parasite

Steps of the Scientific Method

2)2) Ask Questions (Collect Information)Ask Questions (Collect Information)(a) Why doesn(a) Why doesn ’’ t the flashlight work?t the flashlight work?(b) How does a flashlight work?(b) How does a flashlight work?

3)3) Form a hypothesis (Educated Guess)Form a hypothesis (Educated Guess)The batteries are dead! The batteries are dead!

4)4) Experimentation:Test of hypothesisExperimentation:Test of hypothesisReplace the batteries.Replace the batteries.

5)5) Collect results & Draw a conclusionCollect results & Draw a conclusion(a) It works (a) It works –– hypothesis supportedhypothesis supported(b) It doesn(b) It doesn ’’ t work t work –– hypothesis rejectedhypothesis rejected

1)1) ObservationObservationThe flashlight doesnThe flashlight doesn ’’ t work!t work!

(go to step 3)(go to step 3)

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• In mimicry

• A harmless species resembles a harmful species

A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations

Field Experiments with Mimicry….• In this study:

• Mimicry in king snakes is examined

• The hypothesis predicts that predators in non–coral snake areas will attack king snakes more frequently than will predators that live where coralsnakes are present

Key

Kingsnake

Coralsnake

NorthCarolina

SouthCarolina

Eastern Coral snakes are lethal to most predators… so….

Field Experiments with Artificial Snakes

• To test the mimicry hypothesis

(a) Artificial king snake

(b) Brown artificial snake that has been attacked

Researchers made hundreds of artificial snakes, an

experimental group:resembled king snakes

control group: of plain brown snakes

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• After four weeks the researchers collected the model snakes… (the data!)

And in this case the data on incidence of predation fit a key prediction…..

Key

% attacks on “kingsnakes”

% of attacks on brown “snakes”

Field sites

Coralsnakes present: most attacks onbrown models

17%

83%

XXXX X

XX

XX XXX

XX

84%

16%

Key

Coralsnakes absent: most attacks onkingsnake models

Limitations of the Scientific MethodLimitations of the Scientific Method

Remember:Remember:

•• Science seeks Science seeks naturalnatural causes for causes for naturalnatural phenomena.phenomena.

•• The scope of science is limited to the study of The scope of science is limited to the study of structures and processes that structures and processes that we can observe and we can observe and measuremeasure , either directly or indirectly., either directly or indirectly.

•• Verifiable observations and Verifiable observations and measurementsmeasurements are part of are part of science.science.

•• Results are Results are repeatablerepeatable . . (Scientists (Scientists publishpublish their their findings, so other scientists findings, so other scientists can verify them)can verify them)

• EVOLUTION…

• Came into sharp focus in 1859 when Charles Darwin published On the Origin of Species by Natural Selection

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• Darwin proposed natural selection

• As the mechanism for evolutionary adaptation of populations to their environments

Populationof organisms

Hereditaryvariations

Differences in reproductive success

Evolution of adaptationsin the population

Overproductionand struggle forexistence

Natural selection-• is one of the

mechanisms by which evolution occurs…

• When a population’s heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others

1 Populations with varied inherited traits

2 Elimination of individuals with certain traits.

3 Reproduction of survivors.

4 Increasing frequency of traits that enhancesurvival and reproductive success.