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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?
5.
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.