Introduction: Themes in the Study of Lifehome.mca.k12.pa.us/~mudrya/apbio/chemistry/chap1.pdf · 1 Introduction: Themes in the Study of Life Chapter 1 Key Concepts: The themes of

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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?