Download Ch. 01 Introduction to Biology, Biology Today

Chapter 1
Living in a Golden Age of Biology
• We are living in a golden age of biology
• Biology provides exciting breakthroughs
changing our culture.
Introduction: Biology Today
– Molecular biology is solving crimes
and revealing ancestries.
– Ecology helps us address
environmental issues.
– Neuroscience and evolutionary
biology are reshaping psychology
and sociology.
© Jong B. Lee, Ph.D.
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The Scope of Life
• Biology is the scientific study of life: It’s a subject of
enormous scope that gets bigger every year.
e Response to the environment
The properties of Life
f Reproduction
The properties of Life
• What is life?
: The phenomenon of life seems to defy a simple, onesentence definition.
 Order, Regulation, Growth & Development, Energy
utilization, Response to the environment, Reproduction
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a Order
b Regulation
g Evolution
c Growth and development d Energy utilization
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1
Life at Its Many Levels
• The biosphere (생물권) is enriched by a great variety of
ecosystems.
All the environments on Earth that support life
• Biologists explore life at
levels ranging from the
biosphere to the
molecules
• At each new level, novel
properties emerge,
properties that were not
part of the components of
the proceeding level.
“ The whole is greater
than the sum of its parts”
Ex) Life emerges at the
level of cell
• An ecosystem (생태계): consists of all organisms in a
particular area, as well as the nonliving, physical
components of the environment that affect the organisms
• Community (군집): All the organisms in a particular area
• Population (개체군 ): Groups of interacting individuals of
one species (ex: A herd of zebras)
The next: Organisms  organ systems  organs 
tissues  cells  molecules  atoms
Figure 1.2.1
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Ecosystems (생태계)
• Each organism interacts continuously with its
environment, which includes other organisms as well
as nonliving factors.
– Both organisms and environment are affected by the
interactions
– Ecology is the branch of biology that investigates
these relationships between organisms and their
environment
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The dynamics of Ecosystem
The dynamics of any
ecosystem depend on
two processes
– Cycling of
nutrients
(recycle)
– Flow of energy
(one way)
Chemical
energy (food)
Figure 1.3
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Cells and Their DNA
The cell is the lowest level of structure that can perform
all activities required for life
• We can distinguish two major types of cells
– Prokaryotes (원핵생물): bacteria
– All organisms are composed of cells
(unicellular and multicellular)
– Eukaryotes (진핵생물): bacteria 이외의 모든 생물
보통 식물, 동물 들
– Cells: basis for all reproduction, growth, and repair
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Prokaryotic cell (bacterium)
Organelles
• Smaller
• Simpler structure
• DNA concentrated in
nucleoid region, which
is not enclosed by
membrane
• Lacks most organelles
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Eukaryotic cell
• Larger
• More complex
• structure
• Nucleus enclosed
by membrane
• Contains many
types of organelles
Nucleoid
region
Colorized TEM
Nucleus
• The prokaryotic cell is
simple and contains no
organelles
• The eukaryotic cell is more
complex and contains
organelles
• The nucleus is the largest organelle in most eukaryotic
cells
• Eukaryotic cells is subdivided by internal membranes into
organelles.
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How is bacteria able to produce human insulin?
• Though very different in structural
complexity, prokaryotic and eukaryotic cells
have much in common at the molecular level
Genetic engineering and biotechnology have allowed us to
manipulate the DNA and genes of organisms
 human insulin hormone production in bacteria
• All cells use DNA as the chemical material of
genes
It is only possible because biological information is
written in the universal chemical language of DNA
– Genes are the units of
inheritance that transmit
information from parents to
offspring
• The language of DNA contains
just four letters: A, G, C, T
Figure 1.5
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Life in Its Diverse Forms
Human genome의 sequence 해독 완성: 2001
Diversity is the hallmark (상징) of life
– The entire “book” of genetic instructions of an
organism : “Genome”
– Human: 3.2 x 109 base pairs
– The genome sequences of other species
(E. coli, fruit fly, mouse) are completed
– The diversity of known life includes 1.8 million
species ( insects : more than 1 million)
– Estimates of the total diversity range from 10 million
to over 200 million species
– Genomics (유전체학) – a branch of biology that studies
whole genomes
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4
The Three Domains of Life
The kingdoms of life can now
be assigned to three even
higher levels of classification
called domains.
(Bacteria, Archaea, Eukarya)
• Biodiversity can be
both beautiful and
overwhelming
Colorized TEM
DOMAIN
BACTERIA
• Taxonomy is the
branch of biology
that names and
classifies species
Kingdom Plantae
DOMAIN EUKARYA
Grouping Species
Kingdom Fungi
Figure 1.7
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LM
TEM
DOMAIN
ARCHAEA
Kingdom Animalia
Protists (multiple kingdoms)
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Eukarya includes at least four kingdoms
Bacteria and Archaea are both prokaryotic domains
DOMAIN EUKARYA
Kingdom Fungi 곰팡이계
Kingdom Animalia 동물계
Protists 원생생물계 multiple kingdoms
: Generally single celled
LM
Kingdom Plantae 식물계
Figure 1.8.2
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5
• These three multicellular kingdoms (식물, 동물, 곰팡이) are
distinguished by how they obtain food.
– Plants produce their own sugars and other foods by
photosynthesis.
Unity (통일성 ) in the Diversity of Life
Underlying the diversity of life is a striking unity, especially
at the lower levels of structure
Ex: The universal genetic language of DNA
– Fungi are mostly decomposers, digesting dead
organisms.
– Animals obtain food by eating and digesting other
organisms.
What can account for this combination of unit and diversity?
 “Evolution”
• Those eukaryotes that do not fit into the other three
kingdoms are referred the as the protists: generally
singled cells (amoebas..) and multicellular seaweeds
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EVOLUTION: BIOLOGY’S UNIFYING THEME
The history of
life is a saga
(무용담) of a
restless Earth
billions of years
old
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• Each species is one twig of a branching tree of life
extending back in time (화석기록과 유전적 정보를 근거로)
• All of life
is connected
Giant panda
Spectacled bear
Ancestral
bear
Sloth bear
Sun bear
American black bear
: Fossils
document this
history
Asiatic black bear
Common ancestor of
polar bear and brown bear
Polar bear
Brown bear
30
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25
20
15
10
5
Millions of years ago
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6
The Darwinian View of Life
Darwin’s book developed two main points
The evolutionary
view of life came into
focus in 1859 when
Charles Darwin
published The Origin
of Species
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1) Contemporary species arose from a succession of
ancestors
◦ Darwin called this evolutionary history of species
“descent with modification”
(변형되어 혈통잇기 곧 진화를 일컬음)
2) Natural selection (자연선택; 진화의 작동원리)
Darwin proposed a mechanism for descent with
modification, he called this process natural selection.
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Natural Selection
Darwin’s Inescapable Conclusion
• Darwin was particularly struck by the
diversity of animals on the Galapagos
Islands.
• Darwin synthesized the concept of natural selection
from two observations that by themselves were
neither profound nor original
• He thought of adaptation to the environment and the
origin of new species as closely related processes
• Others had the pieces of the puzzle, but Darwin
could see how they fit together.
– If some geographic barrier (an ocean separating
islands) isolated two populations of a single species,
the populations could diverge more and more in
appearance as each adapted to local environmental
conditions. Over many generations, the two
populations could become dissimilar enough to be
designated separate species
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• Observation 1: Overproduction and competition
• Observation 2: Individual variation
(Individuals in a population of any species vary in
many heritable traits)
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• Conclusion:
“ Unequal reproductive success”
– It is this unequal reproductive success that Darwin
called natural selection
Natural selection is the
mechanism of evolution
Avoiding predation is
the key in this case.
– The product of natural selection is adaptation, the
accumulation of favorable variations in a population
over time
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1
Population with varied inherited
traits of
beetles
2
Elimination of individuals with
certain traits
3
Reproduction of survivors
4
Increasing frequency of traits that enhance
survival and reproductive success
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Observing Artificial Selection
Artificial selection is the selective breeding of
domesticated plants and animal by humans (humans were
substituting for the environment in screening heritable trait)
b Domesticated dogs descended from wolves
Domesticated dogs
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Gray wolves
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8
The Process of Science
1. Discovery Science
• The word science is derived from a Latin verb
meaning “to know.”
• Science is a way of knowing.
• Science developed from people’s curiosity about
themselves and the world around them.
• This basic human drive to understand is manifest in two
main scientific approaches: discovery science and
hypothesis-driven science
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• Verifiable observations and measurements are the data
of discovery science.
– In biology, discovery science enables us to describe
life at its many levels.
Ex) Darwin’s careful description of the diverse plants
and animals, The sequencing of the human genomes,
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2. Hypothesis-Driven Science
• Discovery science can
lead to important
conclusions based on
a type of logic called
inductive reasoning.
: An inductive conclusion is
a generalization that
summarizes many
concurrent observations.
(specific  general)
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Revise
Observation:
My flashlight
doesn’t work.
Question:
What’s wrong
with my
flashlight?
Hypothesis:
The flashlight’s
batteries
are dead.
Experiment does
not support
hypothesis; revise
hypothesis or
pose new one.
Prediction:
If I replace the
batteries, the
flashlight will
work.
Experiment:
I replace the
batteries with
new ones.
Experiment
supports
hypothesis;
make additional
predictions
and test them.
• The observations of discovery science stimulate us to
ask questions and seek explanations  As a formal process
of inquiry , the scientific method consists of series of steps.
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The Process of Science: Is Trans Fat Bad for You?
• A hypothesis is a tentative answer to some question.
: It is an explanation on trial.
• In the process of science, the deduction usually
takes the form of predictions about experimental
results.
• Then the hypothesis is tested by performing an
experiment to see whether results are as predicted.
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• A hypothesis-driven study published in 2004
– Started with the observation that human body fat
retains traces of consumed dietary fat.
– Asked the question: Would the adipose tissue of
heart attack patients be different from a similar
group of healthy patients?
– Formed the hypothesis that healthy patients’ body
fat would contain less trans fat that the body fat in
heart attack victims.
• The researchers set up an experiment to determine the
amounts of fat in the adipose tissue of 79 patients who
had a heart attack.
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• One way to better understand how the process of science
can be applied to real-world problems is to examine
a case study, an in-depth examination
of an actual investigation.
• Dietary fat comes in different forms.
: Trans fat is a non-natural form produced through
manufacturing processes.
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2010 Pearson
BIOEducation,
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• They compared these patients
to the data for 167 patients
who had not had a heart
attack.
• This is an example of a
controlled experiment, in
which the control and
experimental groups differ
only in one variable—the
occurrence of a heart attack.
• The results showed significantly higher levels of trans
fat in the bodies of the heart attack patients.
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10
The Culture of Science
Science, Technology, and Society
• Scientists build on what has been learned from earlier
research: They pay close attention to contemporary
scientists working on the same problem.
• Science and technology are interdependent.
- New technologies advance science.
- Scientific discoveries lead to new technologies.
ex) the discovery of the structure of DNA about 50
years ago led to a variety of DNA technologies.
• Cooperation and competition characterize the scientific
culture: Scientists check the conclusions of others by
attempting to repeat experiments.
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• Technology has improved our standard of living in
many ways, but it is a double-edged sword.
- Technology that keeps people healthier has enabled
the human population to double to nearly 7 billion in
just the past 40 years.
- The environmental consequences of this population
growth may be devastating.
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Evolution connection: Evolution in our Everyday Lives
There are many examples of natural selection in action
– Antibiotics have saved millions of human lives, but
there’s a dark side: It has driven the evolution of
antibiotic-resistant populations of bacteria.
– The development of antibiotic-resistant bacteria is
one (예: 결핵균)
• It is important to note that adaptation of antibioticresistant bacteria does not mean that the drugs created
the favorable characteristics.
• Instead, the environment screened the heritable
variations that existed among individuals of a population
and favored the ones best suited to present conditions.
Figure 1.16
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• Darwin’s publication of The Origin of Species
fueled an explosion in biological research
– Evolution is one of biology’s best demonstrated,
most comprehensive, and longest lasting theories
– Dobzansky (1973)
“ Nothing in biology makes sense except in light of
evolution”
 Evolution is the unifying theme of biology
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12