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Chapter 1
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• Biology’s Most Exciting Era
• Biology: scientific study of life
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• The phenomenon we call life
– Defies a simple, one-sentence definition
Figure 1.1
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• Some properties of life
(a) Order
(d) Regulation
(b) Evolutionary
adaptation
(c) Response to the
environment
(e) Energy
processing
(f) Growth and
development
Figure 1.2
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(g) Reproduction
A Hierarchy of Biological Organization
• From the biosphere to organisms
1 The biosphere
Figure 1.3
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• From cells to molecules
9 Organelles
1 µm
Cell
8 Cells
Atoms
10 µm
7 Tissues
50 µm
6 Organs and organ systems
Figure 1.3
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10 Molecules
Ecosystem Dynamics
• 2 major processes
– Cycling of nutrients
– Flow of energy from sunlight  producers 
consumers
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• Energy flows through an ecosystem
– Entering as sunlight and exiting as heat
Sunlight
Ecosystem
Producers
(plants and other
photosynthetic
organisms)
Heat
Chemical
energy
Consumers
(including animals)
Figure 1.4
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Heat
Cells
• Lowest level of organization that can perform
all activities required for life
Figure 1.5
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25 µm
Cell’s Heritable Information
• Chromosomes made partly of DNA, the
substance of genes
– transmit information from parents to offspring
Sperm cell
Nuclei
containing
DNA
Fertilized egg
with DNA from
both parents
Egg cell
e 1.6
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Embyro’s cells
with copies of
inherited DNA
Offspring with traits
inherited from
both parents
The molecular structure of DNA
Nucleus
DNA
Cell
A
C
Nucleotide
T
A
T
A
C
C
G
T
A
G
T
A
(a) DNA double helix. This model shows
Figure 1.7
each atom in a segment of DNA.Made
up of two long chains of building
blocks called nucleotides, a DNA
molecule takes the three-dimensional
form of a double helix.
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(b) Single strand of DNA. These geometric shapes and
letters are simple symbols for the nucleotides in a
small section of one chain of a DNA molecule.
Genetic information is encoded in specific sequences
of the four types of nucleotides (their names are
abbreviated here as A, T, C, and G).
Two Main Forms of Cells
• Eukaryotic
• Prokaryotic
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• Eukaryotic cells
– Subdivided by internal membranes into various
membrane-enclosed organelles
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• Prokaryotic cells
– Lack membrane-enclosed organelles
EUKARYOTIC CELL
PROKARYOTIC CELL
DNA
Membrane
(no nucleus)
Membrane
Cytoplasm
Organelles
Figure 1.8
Nucleus (contains DNA)
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1 µm
• The study of DNA structure, an example of
reductionism
– Has led to the Human Genome Project
Figure 1.9
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Taxonomy
• Classifying life
Species Genus Family
Order
Class
Phylum
Ursus
americanus
(American
black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Figure 1.14
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Eukarya
Kingdom
Domain
• Life’s three domains
Bacteria are the most
diverse
4 µm
and widespread prokaryotes
and are now divided among multiple
kingdoms. Each of the rod-shaped
structures in this photo is a bacterial cell.
DOMAIN ARCHAEA
Figure 1.15
Many of the prokaryotes known
0.5 µm
as archaea live in Earth‘s
extreme environments, such as salty lakes
and boiling hot springs. Domain Archaea
includes multiple kingdoms. The photo
shows a colony composed of many cells.
Protists (multiple kingdoms)
100 µm
are unicellular eukaryotes and
their relatively simple multicellular
relatives.Pictured here is an assortment of
protists inhabiting pond water. Scientists are
currently debating how to split the protists
into several kingdoms that better represent
evolution and diversity.
Kingdom Plantae consists of
multicellula eukaryotes that carry
out photosynthesis, the conversion
of light energy to food.
Kindom Fungi is defined in part by the
nutritional mode of its members, such
as this mushroom, which absorb
nutrientsafter decomposing organic
material.
Kindom Animalia consists of
multicellular eukaryotes that
ingest other organisms.
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Carolus Linnaeus’s
Systema Naturae
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Unity in the Diversity of Life
• As diverse as life is there is also evidence of
remarkable unity
15 µm
1.0 µm
Cilia of Paramecium.
The cilia of Paramecium
propel the cell through
pond water.
5 µm
Figure 1.16
Cross section of cilium, as viewed
with an electron microscope
Cilia of windpipe cells. The cells that line the human windpipe are
equipped with cilia that help keep the lungs clean by moving a film
of debris-trapping mucus upward.
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• Evolution accounts for life’s unity and diversity
• The history of life
– Is a saga of a changing Earth billions of years old
Figure 1.17
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• The evolutionary view of life
– Came into sharp focus in 1859 when Charles
Darwin published On the Origin of Species by
Natural Selection
Figure 1.18
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• The Origin of Species articulated two main
points
– Descent with modification
(evolution)
– Natural selection
Figure 1.19
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Natural Selection
• Darwin’s mechanism for evolution
Population
of organisms
Overproduction
and struggle for
existence
Hereditary
variations
Differences in reproductive
success
Figure 1.20
Evolution of adaptations
in the population
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1
Populations with varied inherited traits
2 Elimination of individuals with certain traits.
3 Reproduction of survivors.
4 Increasing frequency of traits that enhance
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Pearson
Education, Inc. publishing as Benjamin
Cummings
Figure
1.21
survival
and reproductive success.
• The products of natural selection
– Are often exquisite adaptations of organisms to
the special circumstances of their way of life
and their environment
Figure 1.22
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Natural selection
• Ancestral species “split” into two or more descendant
species, resulting in a “tree of life”
Large
ground finch
Small
ground
finch
Large cactus
ground finch
Geospiza
magnirostris
Sharp-beaked
ground finch
Geospiza
difficilis
Geospiza
conirostris
Geospiza
fuliginosa
Medium
ground
finch
Cactus
ground finch
Geospiza
fortis
Geospiza
scandens
Seed eater
Large
tree finch
Camarhynchus
psitacula
Medium
Woodpecker
tree finch
finch
Cactospiza
pallida
Mangrove
finch
Camarhynchus
pauper
Gray
warbler
finch
Certhidea
olivacea
Certhidea
fusca
Small tree finch
Camarhynchus
parvulus
Cactospiza
heliobates
Cactus flower
eater
Green
warbler
finch
Vegetarian
finch
Seed eater
Platyspiza
crassirostris
Insect eaters
Ground finches
Figure 1.23
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Tree finches
Bud eater
Warbler finches
Common ancestor from
South American mainland
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• Each species is on twig of a branching tree of
life
– Extending back in time through ancestral
species more and more remote
• All of life
– Is connected through its long evolutionary
history
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The Myth of the Scientific Method
• The scientific method
– Is an idealized process of inquiry
• Very few scientific inquiries
– Adhere to the “textbook” scientific method
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The Nature of Science
1. Science: observation of the world and the
constant testing of theories against nature,
with the requirement that everything that is
to be called science must be testable
–
The character of science matches the
American character
•
Practical, pragmatic, classless, based
on evidence
•
Healthy skepticism
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2. Rational approach to questions
3. Dull slog through failures to reach a
conclusion
4. Answers lead to more questions
5. What is a fact, law, hypothesis, theory?
6. Can only address question that deal with
the natural world
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What science is not
Pseudoscience
e.g. astrology
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Limitations of Science
• Science cannot address supernatural
phenomena
– hypotheses must be testable and falsifiable
and experimental results must be repeatable
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Theories in Science
• Broad in scope
• Generate new hypotheses
• Supported by a large body of evidence
• Explain
• Incorporates confirmed observations, laws, and
successfully verified hypotheses
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• Law – description of how a natural
phenomenon will occur
• Fact – natural phenomenon repeatedly
confirmed by observation, e.g. Venus takes
225 days to go around the sun
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The Culture of Science
• Social activity
– Cooperation and competition
Figure 1.31
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Underlying themes
Table 1.1
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