Transcript File

Introduction to Biology
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Why a Study of Biology is Important?
Societal
•Medicine
•Public Health
• Worldwide Water Crisis
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Why a Study of Biology is Important?
Philosophical
•Evolution
•Genetics
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Why a Study of Biology is Important?
–Personal
• To be informed
• Support your cause
• Make it your life work
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
[bahy-ol-uh-jee]
 Bio
= life
 ...ology
= the study of
 Biology
is the science that studies
life
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The Scientific Method in Action
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A systematic way of gaining information
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The Scientific Method:
Observation
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An observation is a thoughtful and careful
recognition of an event or a fact.
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The careful observation of a phenomenon leads
to a question.
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How does this happen?
What causes it to occur?
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The Scientific Method:
The Hypothesis
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Hypothesizing
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Hypotheses must:
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question an observation
propose possible solutions to questions based on what
is already understood about the phenomenon
be logical
account for all current information
make the least possible assumptions
be testable
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Testing Hypotheses
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Hypotheses need to be tested to see if they are
supported or disproved.
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Disproved hypotheses are rejected
Hypotheses can be supported but not proven
Ways to test a hypothesis:
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Gathering relevant historical information
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Retrospective Studies
Make additional observations from the natural world
Experimentation
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The Scientific Method:
Experimentation
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Experiments
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Experiments attempt to recreation an occurrence
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tests whether or not the hypothesis can be supported or
rejected
There are many types of experiments
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rigorous tests to determine if the solutions are supported
laboratory, clinical trials, surveys, statistical analyses
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Experimental Design
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All experiments have key elements in common:
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Experiments must be controlled
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Experiments use models to recreate occurrences, but in a
controlled setting
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this means that all aspects except for one variable must be kept
constant
usually include any two groups.
– Experimental group: variable is altered, independent variable
– Control group: variable is not altered, dependent variable
model organisms, ISS, cohorts
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Experimental Design
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Experiments must:
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use large numbers of subjects and/or must be
repeated several times (replication)
be independently reproducible
The validity of experimental results must:
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be tested statistically
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be scrutinized by other scientists
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chi-squared test for statistical significance
peer reviewed
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Theory
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If the hypothesis is supported by ample experimental data, it
leads to a theory.
A theory may be defined as a widely accepted, plausible
general statement about a fundamental concept in science.
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The germ theory states that infectious diseases are caused by
microorganisms.
 Many diseases are not caused by microorganisms, so we must be
careful not to generalize theories too broadly.
Theories continue to be tested
 Exceptions identified
 Modifications made
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A Scientific Law
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A scientific law is a uniform and constant fact of nature that
describes what happens in nature.
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Scientific laws promote the process of generalization.
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Inductive reasoning
Since every bird that has been studied lays eggs, we can generalize
that all birds lay eggs.
Once a theory becomes established, it can be used to
predict specific facts.
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An example: All living things come from pre-existing living things.
Deductive reasoning
We can predict that a newly discovered bird species will lay eggs.
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Scientific Communication
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Data is shared with the
scientific community through
research articles published in
scientific journals.
– peer review
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Scientists present preliminary
data at conferences.
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Scientists collaborate directly by
phone and
e-mail.
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A Sample Experiment
Scientific American August 2010
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A Sample Experiment
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Article: Hardt, Marah J. and Safina, Carl. “Threatening Ocean Life from
the Inside Out.” Scientific American August 2010: Vol. 303 2.
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What types of observations were being made?
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State a hypothesis that was tested.
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Describe an experiment that was conducted.
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Discuss a variable that was studied and describe how constants
where maintained in the experiment.
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How was a model system was used to simulate the conditions being
studied.
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How were the complex processes being studied reduced to their
simplest parts?
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What was learned from the experiments?
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The Science of Biology
• Chapter 1
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1.1 The Science of Life
• Biology unifies much of natural life
• Biology attempts to define life
• Biology Living reveals a hierarchical
organization of living systems
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Properties of Life
• Living organisms:
– are composed of cells (Cellular Organization)
– are complex and ordered (Ordered Complexity)
– respond to their environment (Sensitivity)
– can Grow, Develop and Reproduce
– obtain and use energy (Energy Utilization)
– maintain internal balance (Homeostasis)
– allow for Evolutionary Adaptation
• The definitions of life are adapting with the field
- where do viruses fit in?
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Levels of Organization
1. Cellular Level
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Atoms
molecules
organelles
cells
2. Organismal Level
• Tissues
organs
organ systems
3.Population Level
• Population
species
biological community
4. Ecosystem Level
• Biological community + physical habitat (soil, water,
atmosphere)
5. The Biosphere
• The entire planet thought of as an ecosystem
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4
Levels of Organization
• Cellular Organization
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organelles
•
molecules
•
atoms
cells
• The cell is the
• basic unit of life.
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Fig. 1.1-1
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Levels of Organization
• Organismal Level
•
organism
•
organ systems
•
organs
•
tissues
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Fig. 1.1-2
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Levels of Organization
• Population Level
•
ecosystem
•
community
•
species
•
population
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Fig. 1.1-3
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Levels of Organization
• Each level of organization builds on the
level below it but often demonstrates new
features
• Emergent properties: new properties
present at one level that are not seen in
the previous level
• New properties emerging may be greater
than the sum of the the parts
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1.2 The Nature of Science
• Science aims to understand the natural
world through observation and reasoning
• Science begins with observations,
therefore, much of science is purely
descriptive
• Science uses both deductive and
inductive reasoning
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The Nature of Science
• Deductive reasoning uses general
principles to make specific predictions.
• Inductive reasoning uses specific
observations to develop general
conclusions.
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The Nature of Science
• Scientists use a systematic approach to
gain understanding of the natural world:
– Observation
– Hypothesis formation
– Prediction
– Experimentation
– Conclusion
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The Nature of Science
• A hypothesis is a possible explanation
for an observation.
• A hypothesis:
– must be tested to determine its validity
– is often tested in many different ways
– allows for predictions to be made
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The Nature of Science
• The experiment:
– tests the hypothesis
– must be carefully designed to test only
one variable at a time
– consists of a test experiment and a
control experiment
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The Nature of Science
• If the hypothesis is valid, the scientist can
predict the result of the experiment
• Conducting the experiment to determine if
it yields the predicted result is one way to
test the validity of the experiment
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Think Like a Scientist
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The Nature of Science
• Scientists may use:
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reductionism - to break a complex
process down to its simpler parts
– models – to simulate phenomena
that are difficult to study directly
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Test the early hypothesis of
Spontaneous Generation
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Fig. 1.4
The Nature of Science
• A scientific theory:
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is a body of interconnected
concepts
– is supported by much experimental
evidence and scientific reasoning
– expresses ideas of which we are
most certain
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1.3 An Example of Scientific
Inquiry: Darwin and Evolution
• Charles Darwin served as naturalist on
mapping expedition around coastal South
America.
• Used many observations to develop his
ideas
• Proposed that evolution occurs by
natural selection
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Voyage of the Beagle
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Charles Darwin
• Evolution: Modification of a species over
generations
– “descent with modification”
• Natural Selection: Individuals with
superior physical or behavioral
characteristics are more likely to survive
and reproduce than those without such
characteristics
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Darwin’s Evidence
• Similarity of related species
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Darwin noticed variations in related species
living in different locations
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Unnatural Selection
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Darwin’s Evidence
• Thomas Malthus:
• Population growth vs. availability of
resources
• -population growth
• is geometric
• -increase in food
• supply is arithmetic
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Darwin’s Evidence
• Population growth vs. availability of
resources
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Darwin realized that not all members of a
population survive and reproduce
• Deduced that the organisms best adapted
to obtaining resources would survive to
reproduce
• Darwin based these ideas on the writings
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of Thomas Malthus
Post-Darwin Evolution Evidence
• Fossil record
– Intermediate Organisms
• Mechanisms of heredity
–- Early criticism of Darwin’s ideas were
resolved by Mendel’s theories for genetic
inheritance
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Post-Darwin Evolution Evidence
• Comparative anatomy
• - Homologous structures have same
evolutionary origin, but different structure
and function.
• - Analogous structures have similar
structure and function, but different
evolutionary origin.
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Homologous Structures
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Post-Darwin Evolution Evidence
• Molecular Evidence
• - Our increased
understanding of
DNA and protein
structures has led to
the development of
more accurate
phylogenetic trees.
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1.4 Unifying Themes in Biology
• Cell theory
• The cell theory describes the organization of
living systems
• All living organisms are made of cells, and
all living cells come from preexisting cells
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Single Celled Organisms
Fig. 1.11a
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Multi-Cellular Organisms
Fig. 1.11b
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1.4 Unifying Themes in Biology
• Molecular basis of inheritance
• The molecular basis of inheritance explains
the continuity of life
• DNA encodes genes which control living
organisms and are passed from one
generation to the next
• The DNA code is similar for all organisms
(The Central Dogma)
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Fig. 1.12
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Unifying Themes in Biology
• Structure and Function
• The proper function of a molecule is
dependent on its structure
• The structure of a molecule can often tell
us about its function
• Four major classes of Biomolecules
1. Nucleic Acids
2. Amino Acids
3. Lipids
4. Carbohydrates
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Unifying Themes in Biology
• Evolutionary Change
• The diversity of life arises by evolutionary
change leading to the present biodiversity we
see
• Biology attempts to classify life’s great
diversity based on these unifying themes
• Currently all living things are classified into 3
Domains subdivided into Kingdoms (more on
taxonomy to come)
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• This process is always changing
The Diversity of Life
Three Domains:
1. Eukarya
2. Archaea
3. Bacteria
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Fig. 1.13
Domain Eukarya is
Divided into four
Kingdoms:
1. Plantae
2. Fungi
3. Animalia
4. Protista
Fig. 1.13-1
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Fig. 1.13-2
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Fig. 1.13-3
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Unifying Themes in Biology
• Evolutionary Conservation
• Evolutionary conservation explains the unity
of living systems
• The underlying unity of biochemistry and
genetics argues that all life has evolved from
the same origin event
• Critical characteristics of early organisms are
conserved and passed on to future
generations
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Homeodomains
Fig. 1.14
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Unifying Themes in Biology
• Cells are information-processing
systems
• Every cell in an organism carries the same
genetic information
• The control of gene expression allows cells
to differentiate into different cell and tissue
types
• Cells also process information received
from the environment and respond to
maintain homeostasis
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Unifying Themes in Biology
• Emergent properties
• New properties are present at one level of
organization that are not seen in the
previous level
• The whole is greater than the sum of its
parts
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The Science of Biology
• End Chapter 1
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