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Overview: Inquiring About Life
An organisms adaptations to its environment
are the result of evolution
For example, the ghost plant is adapted toconserving water; this helps it to survive in the
crevices of rock walls
Evolution is the process of change that has
transformed life on Earth
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Order
Regulation
Reproduction
Response to the
environment
Evolutionary adaptation
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Concept 1.1: The themes of the book
make connections across differentareas of biology
Biology consists of more than memorizing
factual details
Themes help to organize biological information
to aid scaling across space and time.
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Theme: New Properties Emerge at
Each Level in the Biological Hierarchy
Life can be studied at different levels, frommolecules to the entire living planet
The study of life can be divided into differentlevels of biological organization
Global.Molecular
Emergent properties result from the
arrangement and interaction of parts within asystem and characterize non-biological entities aswell
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The Biosphere
Ecosystems
Communities
Organisms
Organs and
organ systems
Tissues
Organelles Cells
Molecules
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The Power and Limitations of
Reductionism
Reductionism is the reduction of complexsystems to simpler more easily studiedcomponents
For example, studying the molecular structure of DNAhelps us to understand the chemical basis of inheritance
An understanding of biology balancesreductionism with the study ofemergent
properties For example, new understanding comes from studyingthe interactions of DNA with other molecules
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Systems Biology
A system is a combination of componentsthat function together
Systems biology constructs models for the
dynamic behavior of whole biological systems
The systems approach poses questions suchas
How does a drug for blood pressure affect otherorgans?
How does increasing CO2 alter the biosphere?
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Humans have modified our environment
For example, half the human-generated CO2 staysin the atmosphere and contributes to global
warming
Global warming is a major aspect ofglobal
climate change
It is important to understand the effects of
global climate change on the Earth and its
populations
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Theme: Structure and Function Are
Correlated at All Levels ofBiological
Organization
Structure and function of living organisms are
closely related
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Theme: The Cell is the basic unit of an
Organisms Structure and Function
The cell is the lowest level of organization
that can perform all activities required for life
All cells Are enclosed by a membrane
Use DNA as their genetic information
Prokaryotic cells (no organelles) Eukaryotic cell (organelles)
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Theme: The Continuity of Life Is Based
on Heritable Information in the Formof DNA
Chromosomes contain most of a cells genetic
material in the form ofDNA (deoxyribonucleicacid)
DNA is the substance of genes
Genes are the units of inheritance thattransmit information from parents to offspring
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DNAStructure and Function
Each chromosome has one long DNA molecule
with hundreds or thousands of genes
Genes encode information for building proteins
Proteins are the ones that do the work in the cell
(development and makes the organism)
DNA is inherited by offspring from their parents
DNA controls the development and maintenanceof organisms
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Cells and heredity through DNA
Cells contain chromosomes made partly of
DNA (the substance of genes) which program
a cells production of proteins and transmit
information from parent to offspring
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Each DNA molecule is made up of two long chainsarranged in a double helix
Each link of a chain is one of four kinds ofchemical building blocks called nucleotides andnicknamed A, G, C, and T
Genes control protein production indirectly
DNA is transcribed into RNA then translated intoa protein (central dogma)
Gene expression is the process of convertinginformation from gene (DNA) to cellular product
Genome - The entire library of geneticinstructions that an organism inherits
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Theme: Feedback Mechanisms
Regulate Biological Systems Feedback mechanisms allow biological processes
to self-regulate
Negative feedback means that as more of aproduct accumulates, the process that creates it
slows and less of the product is produced
Positive feedback means that as more of aproduct accumulates, the process that creates it
speeds up and more of the product is produced
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Evolution: An Overarching Biological
Theme
Evolution makes sense of everything we know
about biology and explains patterns ofunity
and diversity in living organisms
Organisms are modified descendants of common
ancestors
Similar traits among organisms are explained by
descent from common ancestors Differences among organisms are explained by
the accumulation of heritable changes
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Concept 1.2: The Core Theme:
Evolution accounts for the unity anddiversity of life or.Uhh, you know
the same, but different Nothing in biology makes sense except in the light of
evolutionTheodosius Dobzhansky Approximately 1.8 million species have been identified
6300 Prokaryotes
100,000 Fungi
290,000 Plants 52,000 Vertebrates
1,000,000 Insects
total number of spp estimated at 10 M to 100 M
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Taxonomy is the branch of biology that names
and classifies species into groups of increasing
breadth
Domains, followed by kingdoms, are the
broadest units of classification
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Unityin the Diversityof Life
A striking unity underlies the diversity of life;
for example
DNA is the universal genetic language common to
all organisms
Unity is evident in many features of cell structure
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Charles Darwin published On the Origin of
Species by Means of Natural Selection in 1859 Darwin made two main points
Species showed evidence of descent with
modification from common ancestors
Natural selection is the mechanism behind
descent with modification
Darwins theory explained the duality of unity
and diversity
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Darwin observed that
Individuals in a population vary in their traits, many ofwhich are heritable
More offspring are produced than survive, andcompetition is inevitable; surviving individuals generallysuit their environment
Darwin inferred that Individuals that are best suited to their environmentare more likely to survive and reproduce
Over time, more individuals in a population will have
the advantageous traits Evolution occurs as the unequal reproductive
success of individuals
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Or the environment selects for the
propagation of beneficial traits that promotesurvival and reproduction
4
Darwin called this process natural selectionthat could cause a single ancestral species togive rise to two or more descendent
species..
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Concept 1.3: In studying nature,
scientists make observations andthen form and test hypotheses
Inquiry is the search for information andexplanation and Biologists observe & describenatural structures and processes
Biology blends two main processes of scientific
inquiry Discovery science (describing nature)
Hypothesis-based science (explaining nature)
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Data
Data are recorded observations or items of
information; that may be:
Qualitative data, or descriptions rather than
measurements (e.g., Jane Goodalls observations of
chimpanzee behavior)
Quantitative data, or recorded measurements,
which can be presented in tables and graphs
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Inductive Reasoning and Hypotheses
Inductive reasoning draws conclusions through thelogical process of induction
Generalization on instances
Repeating specific observations can lead to importantgeneralizations: E.g., the sun always rises in the east
Observations and inductive reasoning can lead us toask questions and propose hypothetical explanations(tentative answers) called hypotheses
A scientific hypothesis leads to predictions that can be tested byobservation or experimentation
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Deductive Reasoning and Hypothesis
Testing
Deductive reasoning uses general premises tomake specific predictions
For example, if organisms are made of cells
(premise 1), and humans are organisms (premise 2),then humans are composed of cells (deductiveprediction)
Hypothesis-based science often makes use of
two or more alternative hypotheses, butfailure to falsify a hypothesis does not provethat hypothesis correct
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Questions without testable
hypotheses
cannot be Addressed by Science A hypothesis must be testable and falsifiable
For example, a hypothesis that ghosts fooled with
the light switch cannot be tested Hypotheses that cannot be tested e.g.
supernatural and religious explanations are
outside the bounds of science
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The Flexibility (slop) in the
Scientific Method
The scientific method is an idealized processof inquiry
Hypothesis-based science is based on the
textbook scientific method, but rarelyfollows all the ordered steps as biologicalsystems are complex and may not easily fitthe textbook method.
In science, observations and experimentalresults must be repeatable
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Concept 1.4: Science benefits from a
cooperative approach and diverse
viewpoints Most scientists work in teams, which often
include graduate and undergraduate studentsand rely on good communication (seminars,publications, and websites, etc)
Scientists check each others claims byperforming similar experiments
Scientists cooperate by sharing data aboutmodel organisms (e.g., the fruit fly Drosophilamelanogaster) or anything that they publish.
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Science, Technology, and Society
The goal of science is to understand naturalphenomena marked by discoveries
The goal oftechnology is to apply scientific
knowledge for some specific purpose marked by inventions
Ethical issues can arise from new technology,
but have as much to do with politics,economics, and cultural values as with scienceand technology