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Chapter 1. The Science of Biology. 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- 1 st discovered cells in cork. 7 Characteristics shared by all living organisms.

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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

  • Malthus’s An Essay on the Principle of Population (1798) played a key role in Darwin’s proposal.

  • Artificial selection: breeder selects for desired traits

  • Natural selection: environment selects for desired traits

  • Waited 16 yrs before publishing

  • Alfred Russel Wallace’s essay encouraged him

    • Joint presentation in London


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Darwin’s 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

    • Mendel’s 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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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

    • A=T

    • G=C

  • 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.