Transcript The Science of Biology

Chapter 1
The Science of Biology
What is SCIENCE?
Science: A process of investigation, using
observation, experimentation and reasoning.
Experimentation must be objective and reproducible!
Science has limitations-it is not always absolutely and eternally correct!!
Science vs. Non-science
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Biology
Chemistry
Geology
Physics
Meteorology
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Art
Astrology
Philosophy
Religion
Extrasensory
Perception
Biology
The study of living things
Biology
includes….
Ecology
Diversity
Behavior
Anatomy
Evolution
Genetics
Microbiology
Biology studies living things….
What does it mean to be “living”?
Characteristics of Life
• What qualifies something as “living” versus “nonliving?”
• Consider these points
 complexity
 movement
 response to stimulation
• A life-defining property must be exclusive to
living things
How do you determine
LIVING from non-living
things?
Use the paper provided to record whether each
of the following slides shows a living or nonliving object!
Properties of Life
• All living things share five basic properties:
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Cellular organization
Metabolism
Homeostasis
Growth and Reproduction
Heredity
5 Basic Properties of Life
1. Cellular organization
 all living things are comprised of at least one
cell
• single cell (bacteria) up to trillions of cells (human)
 Smallest level of organization that can be
considered “alive”
 Membrane-bound
 May contain organelles
 Explained by the Cell Theory
5 Basic Properties of Life
2. Metabolism
 all living things process energy which is used to power other
processes
 Energy source can vary
• Autotrophs
• Heterotrophs
 Nutrients are turned into energy through cellular processes
• Photosynthesis
• Cellular respiration
– Glycolysis
– Krebs Cycle
5 Basic Properties of Life
3. Homeostasis
 all living things maintain stable internal
environments to optimize conditions for
metabolism and other processes
5 Basic Properties of Life
4. Growth and reproduction
 all organisms have the capacity for growth
and reproduction
 Often a trade-off between the two
 Different life-strategies
• Semelparity vs. Iteroparity
Basic Properties of Life
5. Heredity
 all organisms pass genetic information across
generations from parents to offspring
 Theory of Heredity
• Gregor Mendel
 Gene Theory
Properties of Life
• All living things share five basic properties:
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Cellular organization
Metabolism
Homeostasis
Growth and Reproduction
Heredity
Living things are very diverse…
Scientists need a system to name and
classify things!
We call this system….
Taxonomy
Taxonomy
• Began with Linnaeus
• Binomial nomenclature
 Genus + species
 (ie) Homo sapiens
• Hierarchical Classification
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(Domain)
Kingdom
Phylum
Class
Order
Family
Genus
species
Taxonomy Mnemonics!
• Kingdom
• King
• Keep
• Phylum
• Phillip
• Patty’s
• Class
• Came
• Class (in)
• Order
• Over
• Order
• Family
• For
• For
• Genus
• Good
• Goodness
• species
• spaghetti!
• sake!
The Six Kingdoms of Life
Scientists group organisms based on similarities
into six kingdoms
Archaea
Fungi
Bacteria
Plantae
Protista
Animalia
Classifying Life’s Diversity
• Each of the six kingdoms
are assigned, on the
basis of cell structure into
one of three domains
 Bacteria
 Archaea
 Eukarya
Classification of living things
• Taxonomy
 Identifying and classifying organisms
according to specific criteria
 Each taxon is more exclusive than the one
before it
 Ultimately, each organism has its own Genus
species combination that includes a unique
set of traits
• e.g. Homo sapiens = modern humans
Figure 1.4
KINGDOM
(Animalia)
PHYLUM
(Chordata)
CLASS
(Mammalia)
ORDER
(Primates)
FAMILY
(Hominidae)
GENUS
(Homo)
SPECIES
(sapiens)
The Organization of Life
• Living things function and interact with
each other on many levels
• The organization of life is a hierarchy of
levels of increasing complexity
 Cellular
 Organismal
 Ecological (populational)
Cellular Level
• Molecules
 Atoms combine to
make molecules
• Organelles
 Structures within cells
that perform dedicated
functions
• Cells
 Membrane-bound
untis
Organismal Level
• Tissues
 Collection of cells that work together to perform a specialized
function
• Organs
 Group of tissues formed together to perform specialized functions
• Organ systems
 group of related organs that work together
• Organism
 Individual living thing resulting from organ systems working
together to achieve homeostasis
Ecological
(populational) Level
• Population
 Group of organisms of same
species living together
• Species
 All populations of a specific
kind of organism
• Community
 Populations of different
organisms that interact with
one another living in a
particular area
• Ecosystem
 Created by communities that
interact with each other
The Organization of Life
• At higher levels of the living hierarchy, new
properties become apparent that were absent at
the lower levels
• These emergent properties result from the
interaction of diverse but simpler components
• Many higher order processes that are hallmarks
of life are emergent properties
 metabolism
 consciousness
Biological Themes
• The study of life is organized around general
themes
• 5 biological themes emerge repeatedly at any
hierarchical level of biological study:
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Evolution
Flow of energy
Cooperation
Structure determines function
Homeostasis
EVOLUTION
• Evolution is genetic
change in a species over
time
• The mechanism for
evolution is natural
selection
• The diversity of life is
explained by evolutionary
processes
The Flow of Energy
• all living things require
energy
• energy from the sun flows
through the living world
• organisms acquire energy
differently
• how much energy is
available determines how
many and what kinds of
organisms can live
together in an ecosystem
Detritus
Soil nutrient pool
Decomposer
food web
Cooperation
• As energy and other
resources are limiting,
many organisms have
evolved cooperation as
a means of survival
• SymbiosisRelationship between
2 species living in
same community
• Mutualism
• Parasitism
• Commensalism
Structure Determines
Function
• Evolution favors structures that function in an
adaptive manner
• Many structures are specialized for a particular
function
• The convergence of structure and function
occurs at levels of the organizational hierarchy
Homeostasis
• Homeostasis is a physiological
condition of “steady-state”
• The internal environment of organisms
is remarkably stable
• Organisms act to control their internal
environments so that the complex
processes of metabolism function
efficiently
How Scientists Think
• Science is a process of investigation, using
observation, experimentation, and
reasoning
• REMEMBER
 Science is not always 100% correct
 Individuals are not completely without bias
 Science is limited
• it is limited to organisms and processes that
can be observed and measured
• science cannot be relied upon to solve all
problems
How Scientists Think
• Deductive reasoning uses general
principles to explain specific observations
 It’s not a scientific approach
 Top down (general to specific)
• This form of reasoning is common to many
disciplines, including
 mathematical proofs
 politics
 computing
How Scientists Think
• Inductive reasoning is the way of
discovering general principles from examination
of specific observations
 Bottom-up (specific to general)
• Scientists employ inductive reasoning by forming
and testing possible explanations for specific
observations
• These possible explanations are called
hypotheses
Deductive vs. Inductive Reasoning
• Two boys are playing with a soccer ball
• The boys use 2 different approaches to explain
the result of kicking the ball into the air
• Boy 1: “I've noticed that every time I kick a ball up, it
comes back down, so I guess this next time when I
kick it up, it will come back down too”.
• Boy 2: “I know that Newton’s law of Gravity states
that what goes up must come down, so if I kick a ball
in the air, it must fall back down to the ground”.
Deductive vs. Inductive
• Boy 2
• Boy 1
• Uses known theory or • Uses observations to
law to predict the
predict the result of
result of an event
an event
• Top-down (starting big • Bottom-up (starts
and getting small)
small and gets big)
Many times, cases can be supported using both inductive and
deductive arguments. They are not mutually exclusive!
Stages of a Scientific Investigation
• Biology is a dynamic science with new
ideas appearing and replacing old ones
• Scientists systematically conduct
experiments to evaluate hypotheses about
observed phenomena
• These experimental results can either
support or refute a proposed hypothesis
• They also lead to more questions and
more experimentation!
Science in Action
• The scientific process has 6 steps:
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Observation
Hypothesis
Predictions
Testing
Controls
Conclusion
Stages of a Scientific Investigation
1. Observation
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science begins with careful observation of natural
phenomena
These observations lead to questions
2. Hypothesis
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scientists make an educated guess that might be
true
often scientists formulate multiple ideas about a
phenomenon; these are called alternative
hypotheses
Stages of a Scientific Investigation
3. Predictions
 if a hypothesis is correct, then specific
consequences can be expected
4. Testing
 scientists conduct experiments to attempt to
verify predictions made by hypotheses
Stages of a Scientific Investigation
5. Controls
 experiments usually employ a parallel design
• scientists use a control to assess the influence of
potential factors, called variables
• conditions stay the same in the control in
comparison to the variable condition
6. Conclusion
 a hypothesis that has been tested and not
rejected is tentatively accepted
The scientific process
Theory and Certainty
• The term “theory” means different things
to different audiences
 To scientists
• a theory represents certainty and is a unifying
explanation for a broad range of observations
• Scientists’ acceptance of theory is provisional
 To the general public
• a theory implies a lack of knowledge or guess
Four Theories Unify Biology as a
Science
1. The Cell Theory
2. The Gene Theory
3. The Theory of Heredity
4. The Theory of Evolution
The Cell Theory
• 1665 Cells first discovered by Robert Hooke
• 1839 German biologists Schleiden & Schwann put
forth Cell Theory based on many observations of
theirs and others
• Theory States:
 the cell is the most basic unit of life
 all organisms are composed of at least one cell
 all cells come from pre-existing cells
The Gene Theory
• Genetic information is
encoded in molecules of
deoxyribonucleic acid
(DNA)
• Genes encode specific
proteins or RNA or act to
regulate other genes
• The Theory States:
 the proteins and RNA
encoded by an organism’s
genes determine what it
will be like in terms of form
and function
The Theory of
Heredity
• 1865 Gregor Mendel’s theory of heredity
gave rise to the field of genetics
• The Theory States:
 Genes are passed down through generations
as discrete units, they do not blend together
 Chromosomal theory of inheritance located
Mendelian genes on chromosomes
The Theory of Evolution
• 1859 Charles Darwin
• The theory of evolution
explains the unity and diversity
of life as “descent with
modification”
 All living organisms are related to
one another in a common tree of
descent
• The Theory States
 Changes in genes passed from
parents to offspring result in
changes in future generations of a
population
 Changes will thrive in population if
they are adaptive
 Natural selection is the major
mechanism for this change