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Introduction: Themes in the Study of LifeChapter 1
Key Concepts:
� The themes of this course make connections across different areas of biology
� The Core Theme: Evolution accounts for the unity and
diversity of life
� In studying nature, scientists make observations and them form and test hypotheses
� Science benefits from a cooperative approach and
diverse viewpoints
How is this mother of pearl plant adapted to
it’s environment?
Review
�Biology is the scientific study of life
�What makes a good biologist?
The
Characteristics of Life
Biology has a hierarchical structure
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Emergent Properties
�Emergent Properties result from the arrangement and interaction of parts within a system
The Power of Limitations of Reductionism
� Reductionism is the reduction of complex systems to simpler components that are more manageable to study
� For example, the molecular structure of DNA
� An understanding of biology balances reductionism with the study of emergent properties
� For example, new understanding comes from
studying the interactions of DNA with other
molecules
Systems Biology
� A system is a combination of components that function together
� Systems biology constructs models for the dynamic behavior of whole biological systems
� The systems approach poses questions such as:
� How does a drug for blood pressure affect other
organs?
� How does increasing CO2 alter the biosphere?
Cell
� Cell Theory
� Robert Hooke – coined the term “cell”; cork shavings
� Anton van Leewenhoek – discovered single celled organisms
� Schleiden and Schwann – all living things are composed
of cells
� Virchow – cells come from other cells
Basic Units of Structure and Function
� Lowest level of organization
� All cells:
� Are enclosed by a membrane
� Use DNA as their genetic information
� The ability of cells to divide is the basis of all
reproduction, growth, and repair of multicellular organisms
2 Types of Cells
Prokaryotic
� Do not have a nucleus
� Genetic material resides in their cytoplasm
� Lack membrane-bound
organelles
� Examples: Bacteria, Archaea
Eukaryotic
� Larger than prokaryotes
� Contain membrane-bound organelles
� Membrane-bound
nucleus
� Example: all members of Eukarya
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Cells Provide:
�Heritable information – DNA
�Structure and function
�Interactions with the environment
�Open Systems
�Closed Systems
Feedback Mechanisms
� Feedback mechanisms allow biological processes to self-regulate
�Negative feedback means that as more of a product accumulates, the process that creates it slows and less of the product is produced
� Positive feedback means that as more of a product accumulates, the process that creates it speeds up and more of the product is produced
Unity and Diversity
� Taxonomy – branch of science that names and classifies species
� Domains, followed by kingdoms, are the broadest units of classification
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Charles Darwin and Natural Selection
� Darwin made two main points:
� Species showed evidence of “descent with modification”
from common ancestors
� Natural selection is the mechanism behind “descent
with modification”
� Darwin’s theory explained the duality of unity and diversity
Darwin’s Observations
� Individuals in a population have traits that vary
� Many of these traits are heritable (passed from parents to offspring)
� More offspring are produced than survive
� Competition is inevitable
� Species generally suit their environment
Darwin’s Inferences
� Individuals that are best suited to their environment are more likely to survive and reproduce
� Over time, more individuals in a population will have the advantageous traits
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Scientific Inquiry
� What is it?