Transcript Bio 100 Introduction

BIOLOGY!
The Study of Life
bios = life
ology = study of
What is LIFE?
I know it when I see it!
What are some characteristics
we associate with the “definition”
life?
What are the Properties of Life?
1. Precise organization (order)
2. Homeostasis
3. Response to the environment
4. Energy uptake and use
5. Growth and development
6. Reproduction
7. Ability to Evolve
Properties of Life
1) Order
Properties of Life
2) Homeostasis
Properties of Life
3) Response to
the Environment
Properties of Life
4) Energy Processing
Properties of Life
5) Growth and Development
Properties of Life
6) Reproduction
Properties of Life
7) Evolution & Adaptation
Properties of Life?
1. Precise organization (order)
2. Homeostasis
3. Response to the environment
4. Energy uptake and use
5. Growth and development
6. Reproduction
7. Ability to Evolve
Is It Alive? Why or Why Not?
Cologne Cathedral
Baby Chicken
Escherichia coli bacteria
Hoover Dam
Levels of Organization:
Biosphere
Populations
Ecosystems
Individuals
Communities
Organs or Organ
Systems
Levels of Organization:
Organs or Organ
Systems
Organelles
Tissues
Molecules
Cells
Emergent 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
Emergent Properties.
Life itself is an emergent property
Cells are the simplest units of life.
•The cell is the lowest level of structure that
has all of the properties or qualities we use to
define life.
•Some organisms consist of a single cell,
others are multicellular aggregates of
specialized cells.
The first cells were observed and named by
Robert Hooke in 1665 from a slice of cork.
Hooke’s Compound Microscope
“Observation XVIII" of
the Micrographia
Anton van Leeuwenhoek, was the first to
see single-celled organisms in pond water
and observe cells in blood and sperm.
Anton van Leewenhoek
“No more pleasant site has
met my eye than this!”
Van Leewenhoek`s
simple microscope
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, very
prettily 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.”
THE CELL THEORY
• In 1839, Matthais Schleiden and Theodor Schwann
extrapolated from their own microscopic research
and that of others to propose the cell theory.
• The cell theory postulates that cells are the basic unit of structure
and physiology in all living things.
• One of the great paradigms of Biology…
• Cell Theory is to Biology as the Atomic Theory is to Physics
• But... Thought cells formed spontaneously… in a manner similar to
crystal growth
• In 1855, Rudolf Virchow extended the cell
theory :
•
•
New cells are produced by the division of existing cells.
Critical process in reproduction, growth, and repair of
multicellular organisms.
• All cells are enclosed by a membrane that
regulates the passage of materials between the
cell and its surroundings.
• All cells contain DNA, the heritable material that
directs the cell’s activities.
• Two major kinds of cells - prokaryotic cells and
eukaryotic cells - can be distinguished by their
structural organization.
• The cells of the microorganisms called bacteria and
archaea are prokaryotic. Do not contain organelles.
• All other forms of life have the more complex
eukaryotic cells.
The continuity of life is based on heritable
information in the form of DNA
• Biological instructions for life are encoded
in DNA (deoxyribonucleic acid).
• DNA is the substance of genes.
Genomes (Human and Others)
• The entire “library” of genetic instructions that an
organism inherits is called its genome.
• The genome of a human cell is 3 billion chemical
letters long.
• The “rough draft” of the sequence of nucleotides in the
human genome was published in 2001.
• Biologists are learning the functions of
thousands of genes and how their activities are
coordinated in the development of an organism.
Unity & 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 & Diversity
Taxonomy: classifying and organizing life
7) Unity & Diversity
Taxonomy: classifying and organizing life
species
Spaghetti
Genus
Good
Family
For
Order
Over
Class
Came
Phylum
Phillip
Kingdom
King
Examples from the Animal Kingdom
ORGANISM
GROUP
NAME
HUMAN
CHIMPANZEE
HOUSE CAT
LION
HOUSEFLY
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
Unity & Diversity
• DOMAINS
1. Bacteria
2. Archea
3. Eukarya
1. Plantae
2. Animalia
3. Fungi
4. Protista
= Monera
Unity & Diversity
5 Kingdoms
1.
2.
3.
4.
5.
Monera = Bacteria
Plantae = Plants
Animalia = Animals
Fungi = Fungi
Protista = Protists
Unity & Diversity
Unity within diversity:
• DNA as the common information molecule
• Eukaryotes all share common cellular architecture
The Nature of Science (& “the” scientific method)
“Science is a process of inquiry that
includes repeatable observations
and testable hypotheses.”
A) Discovery
Science (Induction)
B) Hypotheticodeductive model
• Observations
• Scientific method
• Data collection
• Formal process
• In field or lab!
• 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
• Causal Questions: Ask what is CAUSING a
particular phenomenon or observation.
“What causes frog deformities?”
CAUSATION
is 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.
IF the hypothesis is TRUE,
THEN we can predict an outcome.
Hypothesis
Predicted Outcome from a
planned experiment
Test Data:
% deformed frogs in
atrazine water = 0
% deformed frogs in
pure water= 0
Actual Experiment
Causal Question: Question about how or why things occur.
Hypothesis: A testable explanation, a possible answer to a
causal question
Prediction:
An expectation (derived from the hypothesis)
about what you SHOULD see, if you were to do an
experiment or make more observations.
Test:
Evidence (data) derived from an actual experiment or
observation that can be matched against predicted result.
Conclusion: A decision about whether or not the evidence
supports the hypothesis.
Science is a Cycle:
Causal Question
Hypothesis
Conclusion
Prediction
Test (data)
Label each statement: Causal question,
hypothesis, prediction, test/data, and conclusion.
1.
2.
3.
4.
5.
Trematode infection is probably responsible for frog deformities
1. Conclusion
What makes tadpoles produce frogs with extra legs?
2. Causal
Question
The proportion of adult frogs with deformities should increase
with increasing exposure to parasitic infections
3. Prediction
I wonder if infection by trematodes could disrupt tadpole
4. Hypothesis
development?
5. Test
Density of trematodes (per tad)
0
% of frogs w/ limb deformities
0
16
32
48
70
90
100
New Hypothesis: Abnormal development of
frogs is caused by a trematode parasite
Steps of the Scientific Method
1) Observation
The flashlight doesn’t work!
2) Ask Questions (Collect Information)
(a) Why doesn’t the flashlight work?
(b) How does a flashlight work?
3) Form a hypothesis (Educated Guess)
The batteries are dead!
4) Experimentation:Test of hypothesis
Replace the batteries.
5) Collect results & Draw a conclusion
(a) It works – hypothesis supported
(b) It doesn’t work – hypothesis rejected
(go to step 3)
A Case Study in Scientific Inquiry:
Investigating Mimicry in Snake Populations
• In mimicry
• A harmless species resembles a harmful species
Field Experiments with Mimicry….
• In this study:
Key
Kingsnake
• 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
Coralsnake
North
Carolina
South
Carolina
Eastern Coral snakes are lethal to most predators… so….
Field Experiments with Artificial Snakes
• To test the mimicry hypothesis
Researchers made
hundreds of artificial
snakes, an
experimental group:
resembled king snakes
(a) Artificial king snake
control group: of plain
brown snakes
(b) Brown artificial snake that has been attacked
• After four weeks the researchers collected the
model snakes… (the data!)
Key
Key
% attacks on “kingsnakes”
% of attacks on brown “snakes”
Field sites
17%
And in this case
the data on
incidence of
predation fit a
key
prediction…..
Coralsnakes absent:
most attacks on
kingsnake models
83%
X
XX
X
XX
XXX
X
XXX
X
Coralsnakes present:
most attacks on
brown models
16%
84%
Limitations of the Scientific Method
Remember:
• Science seeks natural causes for natural phenomena.
• The scope of science is limited to the study of
structures and processes that we can observe and
measure, either directly or indirectly.
• Verifiable observations and
measurements are part of
science.
• Results are repeatable.
(Scientists publish their
findings, so other scientists
can verify them)
• EVOLUTION…
• Came into sharp focus in 1859 when Charles
Darwin published On the Origin of Species by
Natural Selection
• Darwin proposed natural selection
• As the mechanism for evolutionary adaptation of
populations to their environments
Population
of organisms
Hereditary
variations
Overproduction
and struggle for
existence
Differences in
reproductive success
Evolution of adaptations
in the population
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 enhance
survival and reproductive success.