The Science of Biology

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Chapter 1

• The Science of Biology

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Introduction to Biology

• What is biology?
• Study of living systems and how they interact
  with their environment

• The cell is the basic unit of life
• 1665-Robert Hooke- 1st discovered cells in cork

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7 Characteristics shared by all living organisms

• are composed of cells
• are complex and ordered
• respond to their environment
• can grow and reproduce
• obtain and use energy
• maintain internal balance
• allow for evolutionary adaptation

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Hierarchical Organization of Living Systems

• Cellular level
• Atoms? Molecule? Macromolecule? Organelle? Cell
• Organismal level
• Tissue? Organ? Organ system? Organism
• Populational level
• Population? Species? Community? Ecosystem?
  Biosphere
• Ecosystem level
• Emergent Properties at every level
• Novel properties not seen in previous level
• The Biosphere
• Each level builds on the previous

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Deductive Reasoning vs. Inductive Reasoning

• Uses general principles to make specific
  predictions
• Mathematics/ Philosophy
• Example If all birds are defined as having wings
  and you discover a bird that does not have wings,
  you conclude the animal is not a bird.

• uses specific observations to develop general
  conclusions
• Example If eagles have wings and hummingbirds
  have wings, then you may conclude that all birds
  have wings.

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Scientific Method

• Scientists use a systematic approach to gain
  understanding of the natural world.
• -Observation
• -Hypothesis formation
• -Prediction
• -Experimentation
• -Conclusion

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Scientific Method

• A hypothesis is a possible explanation for an
  observation
• Must be tested to determine validity
• Tested multiple ways
• Allows predations to be made
• The experiment tests the hypothesis
• Test one variable at a time
• Consists of both a control and test experiment
• If the hypothesis is valid, results can be
  explained
• Scientists may also use
• Reductionism-break down complex parts into
  simplified
• Models-to simulate phenomena that are difficult
  to study
• A scientific theory is a body of interconnected
  concepts

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Darwin Evolution

• English naturalist
• Descent with Modification
• 5 yrs on H.M.S. Beagle
• Proposed natural selection as a mechanism for
  evolution

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Natural Selection

• individuals with superior physical or behavioral
  characteristics are more likely to survive and
  reproduce than those without such characteristics
• Evolution- modification of a species over
  generations
• -descent with modification

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Darwin

• Malthuss An Essay on the Principle of Population
  (1798) played a key role in Darwins proposal.
• Artificial selection breeder selects for desired
  traits
• Natural selection environment selects for
  desired traits
• Waited 16 yrs before publishing
• Alfred Russel Wallaces essay encouraged him
• Joint presentation in London

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Darwins Evidence

• Similarity of related species
• Population growth vs. availability of resources

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Post-Darwin Evidence

• Fossil record
• New fossils are being found
• Mechanisms of heredity
• Mendels theory of genetic inheritance
• Comparative anatomy
• Homologous vs. analogous structures
• Molecular evidence

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Homologous vs. Analogous Structures

• Homologous have same evolutionary origin, but
  have different structure and function
• Analogous have similar structure and function,
  but different evolutionary origin

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Unifying Themes in Biology

• Cell Theory
• All Living organisms consist of cells
• Cells come from other cells
• Molecular Basis of Inheritance
• Relationship between Structure Function
• Evolution
• Emergence of Novel Properties

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3 Domains of life
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4 Kingdoms
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Unifying Themes in Biology

• Cell theory- All living things are composed of
  cells and all preexisting life comes from cells
• 1839 German biologists Schleiden and Schwann
• Molecular basis of inheritance- DNA encodes genes
  which control living organisms and are passed
  from one generation to the next

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DNA Structure

• 2 strands make double helix
• Spiral staircase
• Base pairs
• AT
• GC
• Complementary sequence

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Relationship between 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.

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Unifying Themes

• Evolutionary change Living organisms have
  evolved from the same origin event. The
  diversity of life is the result of evolutionary
  change.
• Evolutionary conservation Critical
  characteristics of early organisms are preserved
  and passed on to future generations.
• Think of cells as information-processing systems
• They process information stored in DNA as well as
  information received from the environment.
• Emergent properties are seen at one level of
  organization that are not seen in the previous
  level.