Transcript Introduction

BSC 2010
Suzanne Butler
1271-9
(305)237-8118
[email protected]
Textbooks
• Required text
Biology, 6th ed. Neil Campbell and J. Reese.
2002. Benjamin Cummings.
• Optional Textbook
Chemistry for Biology Students, 7th ed. by George Sackheim
Introduction: Ten Themes in
the Study of Life
Chapter 1
Biology
Scientific study of life
Lays the foundation
for asking basic questions about life
and the natural world
Evolution of Biology As a Science
• Through the Middle Ages
– Major scientific discoveries were made in early
Egypt, Babylonia, and Greece
– Between 200 and 1200 AD there were almost
no important scientific advances
– No real distinction made between science and
theology
– Not much questioning of anything
Evolution of Biology As a Science
• Intellectual Reawakening in Europe
– Albertus Magnus and Thomas Aquinas
• Theologians and philosophers teaching in Paris
• Prepared the way for more independent development of
science
– Roger Bacon
• Called for an end to unthinking acceptance of classical
writings such as Aristotle
“Cease to be ruled by dogmas and authorities; look at the
world.”
Evolution of Biology As a Science
• New Era in the Physical Sciences
– Copernicus and Galileo
• said the earth was not the center of the universe
• Led to the conclusion that the earth can be understood in
terms of universal laws
– Isaac Newton
• Discovery of the Laws of Gravitation
• explanations in 1685 of the movements of planets
• Caused a revolution in human thought
• Moved physical science into new era
Evolution of Biology As a Science
• New Era in Biological Sciences
– Did not begin until the middle of the
nineteenth century
– Began when Pasteur finally disproved
“spontaneous generation”
– Darwin’s work on evolution was the beginning
of the same kind of revolution in biology that
Newton’s began in physics
Spontaneous Generation
• Prevailing scientific view for over 300 years
• Organisms are regularly generated from non
living materials
– Put Garbage in the street
• Rats generate spontaneously
– Hang meat in open stalls
• Maggots appear
– Put broth on the window sill to cool
• Bacteria grow
DisprovingSpontaneous
Generation
• Francesco Redi
– performed an experiment to check whether
maggots really came from decaying meat
– placed meat in a number of jars and covering
half of them with fine gauze while leaving the
others uncovered
– Maggots developed only on the meat in the
uncovered jars
Argument in Support of
Spontaneous Generation
• the belief in spontaneous generation remained strong, and even
Redi continued to believe it occurred under some circumstances
• invention of the microscope only served to enhance this belief
– a whole new world of organisms that appeared to arise spontaneously
• John Needham
– knew that boiling killed microorganisms
– boiled chicken broth, put it into a flask, sealed it, and
- sure enough, microorganisms grew
– claimed victory for spontaneous generation
Disproving Spontaneous
Generation
• Lazzaro Spallanzani
– almost one hundred years after Redi’s experiments modified Needham’s
experiment
Argument Supporting
Spontaneous Generation
• Spallanzani had only proven that
spontaneous generation could not occur
without air.
DisprovingSpontaneous
Generation
• Louis Pasteur
– Boiled nutrient mixture in flask with long s-shaped
necks
– Almost all flasks treated this way remained free of
bacterial growth as long as the neck was unbroken
– When Pasteur tilted the flask so that the broth
reached the lowest point in the neck, where any
airborne particles would have settled, the broth
rapidly became cloudy with life
– Concluded that microorganisms were brought into
flask on dust particles rather than generated from the
nutrient mixture
Evolution of Biology As a Science
• New Era in Biological Sciences
– Did not begin until the middle of the
nineteenth century
– Began when Pasteur finally disproved
“spontaneous generation”
– Darwin’s work on evolution was the beginning
of the same kind of revolution in biology that
Newton’s began in physics
The Evolution of Evolution
– Cuvier
• Catastrophism
– One time creation
– Successive catastrophes caused some to become extinct and
others to fluorish
– Lamarck
• Proposed inheritance of acquired characteristics
– Lyell
• Princilpes of Geology, 1830
• Proposed that geological forces still operating could account
for the changes that were seen in the earth’s surface
• Earth not in final form at creation, but steadily undergoing
change
Charles Darwin
• At 8 years old he was intrigued with the
natural world.
• He studied medicine but could not
stomach surgery
• He then studied to be a clergyman, but
spent his time with scientists while at
Cambridge
Darwin’s Voyage
• At age 22, Charles Darwin began a five-year,
round-the-world voyage aboard the Beagle
• In his role as ship’s naturalist he collected and
examined the species that inhabited the
regions the ship visited
Voyage of the Beagle
EQUATOR
Galapagos
Islands
Galapagos
Islands
Darwin
Wolf
Volcanic islands
far off coast of
Ecuador
Pinta
Genovesa
Marchena
All inhabitants are
descended from
species that
arrived on islands
from elsewhere
Santiago
Bartolomé
Fernandia
Seymour
Baltra
Rabida
Pinzon
Santa Cruz
Santa Fe
Tortuga
San Cristobal
Isabela
Española
Floreana
Darwin’s Observations
• In Argentina, Darwin observed fossils
of extinct glyptodonts
• Animals resembled living armadillos
• In the Galapalos Islands he saw strange
iguanas, turtles, and mocking birds that
varied from one island to another
Galapagos Finches
• Darwin observed finches with a variety
of lifestyles and body forms
• On his return he learned that there
were 13 species
• He attempted to correlate variations in
their traits with environmental
challenges
Diversification of finches on the Galápagos Islands
Darwin Begins to Understand
• The Galapagos finches were related to an
•
•
•
ancestral species that could be found on the
mainland of SA hundreds of miles to the east
Members of that ancestral species had come
to the Galapagos by air then fanned out to
separate islands
They had diverged over time into separate
species
Still had no mechanism for driving this
“descent with modification”
Malthus - Struggle to Survive
• Thomas Malthus, a clergyman and
economist, wrote essay that Darwin
read 2 years after his return to
England
• Argued that as population size
increases, resources dwindle, the
struggle to live intensifies and
conflict increases
Darwin’s Theory
• Rejects the notion that living creatures are
immutable products of a sudden creation.
• A population can change over time when
individuals differ in one or more heritable
traits that are responsible for differences in
the ability to survive and reproduce
Figure 1.15 Natural selection
Alfred Wallace
• Naturalist who arrived at the same
conclusions Darwin did
• Wrote to Darwin describing his views
• Prompted Darwin to finally present
his ideas in a formal paper
On the Origin of Species
• Darwin’s book
• Published in 1859
• Laid out in great detail his evidence
in support of the theory of
evolution by natural selection
Two Parts of Darwin’s Theory
• Descent with modification
– Change is the rule rather than the exception
– Organisms living today have descended by gradual changes from
ancient ancestors quite unlike themselves
• Natural selection determines the course of the
change
– It is a completely mechanistic process without conscious purpose
or design
– individuals differ in one or more heritable traits that are
responsible for differences in the ability to survive and reproduce
Populations Evolve
• Biological evolution does not change
individuals
• It changes a population
• Traits in a population vary among
individuals
• Evolution is change in frequency of
traits
Some properties of life
How Do We Know If It is Alive?
• Metabolism
–
–
–
–
Taking in and digesting food
Assimilating digested food
Respiration
Excretion
• Non-living things do not derive energy by
taking in or transforming foreign matter.
Energy utilization
How Do We Know If It is Alive?
• Growth and Development
– Organisms develop new parts between or
within older parts
• Non-living things can grow only by
addition of material to the outside.
Growth and development
How Do We Know If It is Alive?
• Irritability
– Response to environmental stimuli
• Many forms
• May not be proportional to stimulus
• Organism not usually permanently altered by the stimulus
• Non-living things may react to stimuli
– Always a quantitative relationship between the
stimulus and the effect
How Do We Know If It is Alive?
• Reproduction
– Each kind of living thing reproduces itself in
kind
– Information needed to develop and reproduce
is segregated within the organism
– Information needed to develop and reproduce
is passed to offspring
• Non-living things do not reproduce
Reproduction
How Do We Know If It is Alive?
• Evolution and Adaptation
– Groups of organisms change over time
– Changes make organisms more able to live in
the particular local environment
• Non-living things do not change nor
adapt to the environment
How Do We Know If It is Alive?
• Order
– All organisms are highly organized
– Maintain that organization by expending
energy
– Each type usually has definite form and shape
– All organisms are composed of cells
• Non-living things do not maintain their
organization by expending energy
Order
Unity of Life
All organisms:
– Are composed of the same substances
– Engage in metabolism
– Sense and respond to the environment
– Have the capacity to reproduce based
on instructions in DNA
Figure 1.5 The genetic material: DNA
Diversity of Life
• Millions of living species
• Additional millions of species
now extinct
• Classification scheme attempts
to organize this diversity
Five Kingdoms
Classifying life
Structure and Function
• Correlated at all levels of life
• A bird’s shape and it’s skeleton
– Make flight possible
• Aerodynamic shape of wing
• Honeycombed construction of bone
• A cell’s form fits its specialized function
– Nerve cells have long extensions that transmit signals
• At the sub-cellular level
– Inner membrane of mitochondrion is folded to provide
more surface area
Form fits function
Scientific Method
• Observe phenomenon
• Develop hypotheses
• Make predictions
• Devise test of predictions
• Carry out test and analyze
results
Careful observation and measurement provide the raw data
for science
Inductive Logic
• Using observations and facts to arrive
at generalizations or hypotheses
• Observation: Eagles, swallows, and
robins have feathers
• Hypothesis: All birds have feathers
Deductive Logic
• Drawing a specific conclusion based on a
generalization
– Generalization - Birds have feathers
– Example - Eagles are birds
– Conclusion - Eagles have feathers
Idealized version of the scientific method
Role of Experiments
• Procedures used to study a phenomenon
under known conditions
• Allows you to predict what will happen if
a hypothesis is not wrong
• Can never prove a hypothesis 100%
correct
David Reznick conducting field experiments on guppy evolution in Trinidad
Controlled experiments to test the hypothesis that selective predation
affects the evolution of guppy populations
Experimental Design
• Control group
– A standard for comparison
– Identical to experimental group except for
variable being studied
• Sampling error
– Non-representative sample skews results
– Minimize by using large samples
Draw samples from some aspect of nature
CONTROL GROUP
The variable being
tested is absent
EXPERIMENTAL GROUP
The variable being
tested is present
Compile results
Compile results
Compare and analyze the test results
Report on experimental design, test results,
and conclusions drawn from results
Fig. 1.10, p. 12
Scientific Theory
• An hypothesis that has been tested for
its predictive power many times and has
not yet been found incorrect
• Has wide-ranging explanatory power
– Darwin’s Theory of Evolution by Natural
Selection
Limits of Science
• Scientific approach cannot provide
answers to subjective questions
• Cannot provide moral, aesthetic, or
philosophical standards
Science and the Supernatural
• Science has run up against religious
belief systems
– Copernicus suggested that sun, not the Earth,
was center of universe
– Darwin suggested that life was shaped by
evolution, not a single creation event
Asking Questions
• Scientists still ask questions that
challenge widely held beliefs
• The external world, not internal
conviction, is the testing ground for
scientific beliefs
Review of Ten Unifying Themes in Biology
Review of Ten Unifying Themes in Biology (continued)