Transcript INTRODUCTION TO BIOLOGY

INTRODUCTION TO
BIOLOGY
Ch 1
Concepts and Connections
– Biology is connected to many important issues in our
lives
•
Environmental problems and solutions
•
Genetic engineering
•
Medicine
What is 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
• 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
• This was the prevailing scientific view for over
300 years
• Living things can come from non living things.
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
Disproving Spontaneous 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
Pasteur’s Experiment
THE SCOPE OF BIOLOGY
•Life’s levels of organization define the scope of
biology
– Life’s structural hierarchy
•
Defines the scope of biology, the scientific
study of life
Biosphere
Ecosystem
Florida coast
Community
All organisms on
the Florida coast
Population
Group of brown
pelicans
Organism
Brown pelican
Spinal cord
Organ system
Nervous system
Brain
Nerve
Organ
Brain
Tissue
Nervous tissue
Figure 1.1
Cell
Nerve cell
Nucleus
Organelle
Nucleus
Atom
Molecule
DNA
LEVELS OF ORGANIZATION
• The levels in which life is organized are from the largest to the smallest:
Biosphere
Ecosystem
Community
Population
Organism
Organ system
Organ
Tissue
Cell
Organelles
Molecules
Atoms
Each level is built of parts from the lower levels.
With each step up in the organizational levels new
properties emerge.
– An ecosystem consists of all the organisms living in
a particular area
•
As well as the nonliving environmental components
– All the living organisms in an ecosystem
•
Make up a community
– A population
•
Consists of a localized group of individuals of
a species
– An individual living entity
•
Is an organism
• Living organisms and their environments form
interconnecting webs
– Ecosystems are characterized by the cycling of
chemical nutrients from the atmosphere and soil
•
To producers to consumers to decomposers and back
to the environment
Living things do not exist by themselves
• Living things interact with the non-living
components of the environment.
• PRODUCERS-plants use carbon dioxide,
minerals, water, sunlight energy.
• COMSUMERS- animals use plants, minerals,
water, oxygen.
• DECOMPOSERS- such as prokaryotes and fungi
recycle organic matter back to the environment
Two main processes in an ecosystem
• Recycle of chemicals
• Energy flow
• Organisms are open systems that exchange
materials and energy with their
surroundings.
– Energy flows one-way through an ecosystem
•
From the sun to producers to consumers and
exits as heat
Sun
Air
Inflow
of
light
energy
O2
CO2
CO2
Chemical
energy
Producers
Cycling
of
Chemical
nutrients
Decomposers
H2O
Figure 1.2
Consumers
Soil
Ecosystem
Loss
of
heat
energy
• Cells are the structural and functional units of
life
– A cell
•
Is the basic unit of life
All organisms are composed of cells
• Two type of cells:
Prokaryotic cells found in bacteria and archaea
Eukaryotic cells found in plants and animals
What do they have in common?
All cells use DNA as the genetic material
– Eukaryotic cells
•
Contain membrane-enclosed organelles, including
a DNA-containing nucleus
– Prokaryotic cells
Lack such organelles
Nucleus
(contains DNA)
Prokaryotic cell
Eukaryotic
cell
DNA
(no nucleus)
Organelles
Figure 1.3
25,000 
•
– All organisms share a common set of features
•
Ordered structures
•
Regulation of internal conditions
Figure 1.4B
Figure 1.4C
How Do We Know If It is Alive?
Characteristics of life:
1. 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
How Do We Know If It is Alive?
Characteristics of life:
2. 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
Characteristics of life:
• 3. Reproduction- DNA
– 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
Characteristics of life:
• 4. Energy Use
• Organisms cannot live without energy
Metabolism is the sum total of all reactions
involved in getting and using energy
Characteristics of life:
• 5. 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
Characteristics of life:
6. Regulation of internal conditions
• This is also known as Homeostasis.
• The body tries to maintain a state of equilibrium.
Examples:
thermoregulation ( maintaining temperature within
certain limits)
Excretion and hydration
Characteristics of life:
• 7. 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
Characteristics of life:
1.ORDER: all living things have complex organization, are composed of
the same chemical substances and made up of cells
2. REGULATION: organisms regulate their internal environment, this is
called HOMEOSTASIS
3. GROWTH AND DEVELOPMENT: genes control the pattern of
growth and development.
4. ENERGY USE: all organism engage in metabolism.Energy is taken in
and transformed to a usable form
5. RESPONSE TO THE ENVIRONMENT: Sense and respond to the
outside environment
6. REPRODUCTION: Have the capacity to reproduce based on
instructions in DNA
7. EVOLUTION: organisms change over time
• The diversity of life can be arranged into
three domains
– Organisms are grouped (classified)
•
Into the prokaryotic domains Bacteria and
Archaea and the eukaryotic domain Eukarya
The three domains of life
• Domain Archaea (oldest, most primitive)
• Domain Bacteria
• Domain Eukarya
plants
animals
fungi
SEM 3,250
– Domains Bacteria and Archaea
SEM 25,000
Figure 1.5A
Figure 1.5B
– Domain Eukarya includes
•
Protists (protozoans and algae, falling into multiple
kingdoms)
•
The kingdoms Fungi, Plantae, and Animalia
275
Kingdom Fungi
Kingdom Animalia
Protists
(multiple kingdoms)
Figure 1.5C
Kingdom
Plantae
Diversity of Life
• Millions of living species
• Additional millions of species now extinct
• Classification scheme attempts to organize
this diversity
EVOLUTION, UNITY, AND
DIVERSITY
The unity of life: All forms of life have
common features
– DNA is the genetic information
•
For constructing the molecules that make up
cells and organisms
– Each species’ genetic instructions
•
Are coded in the sequences of the four building blocks
making up DNA’s two helically coiled chains
A
C
T
A
T
A
C
C
G
T
A
G
T
Figure 1.4A
A
Figure 1.10 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
• Evolution explains the unity and diversity of life
– Charles Darwin
•
Synthesized the theory of evolution by natural selection
Figure 1.6A
Darwin’s Voyage
• At age 22, Charles Darwin began a fiveyear, 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
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
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
THE PROCESS OF SCIENCE
– Science
•
•
Is a way of knowing
Scientists are always asking questions about nature
and looking for answers about natural phenomena
Scientists use two main approaches to learn about
nature.
•Discovery Science
– In discovery science
•
Scientists describe some aspect of the world
and use inductive reasoning to draw general
conclusions
Inductive Logic
• Using observations and facts to arrive at
generalizations or hypotheses
• Observation: Eagles, swallows, and robins
have feathers
• Hypothesis: All birds have feathers
•Hypothesis-Based Science
– In hypothesis-based science
•
Scientists attempt to explain
observations by testing hypotheses
• With hypothesis-based science, we pose and test
hypotheses
– Hypothesis-based science involves
•
•
Observations, questions, hypotheses as tentative
answers to questions
Deductions leading to predictions, and then tests of
predictions to see if a hypothesis is falsifiable
•A Case Study from Everyday Life
– Deductive reasoning is used in testing hypotheses as follows
•
If a hypothesis is correct, and we test it, then we can
expect a particular outcome
Observations
Question
Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Figure 1.8A
Test falsifies hypothesis
Test prediction
Test does not falsify hypothesis
Deductive Logic
• Drawing a specific conclusion based on a
generalization
– Generalization - Birds have feathers
– Example - Eagles are birds
– Conclusion - Eagles have feathers
Scientific Method
• Observe phenomenon
• Develop hypotheses
• Make predictions
• Devise test of predictions ( experiment)
• Carry out experiment and analyze results
• Draw conclusion
Figure 1.19 Idealized version of the scientific method
Figure 1.21 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
– Minimize by using large samples
– Experiment must be repeatable
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
• A 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, religious
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
• 1. What are the three domains of life/
• 2. What theory explains the “unity and diversity of
life”?
• 3. What is evolution? Who was the first person
that proposed this theory?
• 4. How do scientist go about finding answers to
questions?
• 5. What are three requirements for an experiment
to be valid?
• 6. What is the meaning of the word “theory” in
science?
• 7.What are the limitations of the scientific
method?