Transcript Inductive reasoning

What is Life?
– 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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Fig. 1.1
mitochondria
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Fig. 1.1(continued)
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The Nature of Science
Science aims to understand the natural
world through observation and reasoning.
Science begins with observations, therefore,
much of science is purely descriptive.
Science uses both deductive and inductive
reasoning.
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The Nature of Science
Deductive reasoning uses general
principles to make specific predictions.
Inductive reasoning uses specific
observations to develop general
conclusions.
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The Scientific Way of Knowing:
Inductive and Deductive approaches define the Scientific Method
Often, scientific investigations starts with Induction and moves to Deduction
Theory
(Hypotheses)
Observations,
Previous Research
Induction
Deduction
(specific to general)
(general to specific)
Experiments
Hypotheses
A scientific theory
- is a body of interconnected concepts
- is supported by a large fundament of evidence
and scientific reasoning (usually the testing of
numerous hypotheses)
- expresses ideas of which we are most certain
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Charles Darwin
evolution: modification of a species over
generations
-“descent with modification”
natural selection: individuals with superior
physical or behavioral characteristics are
more likely to survive and reproduce than
those without such characteristics
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One Piece of Darwin’s
Induction
Similarity of related species
- Darwin noticed variations in related
species living in different locations
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Another piece of Darwin’s
Induction
Population growth vs. availability of resources
-population growth
is geometric
-increase in food
supply is arithmetic
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Evolutionary Deductive Evidence
Fossil record
- New fossils are found all the time
- Earth is older than previously believed
Mechanisms of heredity
- Early criticism of Darwin’s ideas were
resolved by Mendel’s theories for genetic
inheritance.
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An Evolution by Natural Selection Primer
• Mutations and their various combinations (hence new varieties)
do not arise because they are needed -- they arise by chance.
• Mutations merely furnish random raw material for evolution,
and rarely, if ever determine the course of the process.
• Natural selection is the differential reproduction of genotypes
(genes). Cumulative selection is a powerfully constructive force,
caught in action many times by evolutionary biologists.
• Evolution is, quite simply, the change in the genetic composition
of a population over time.
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More Evolutionary Deductive
Evidence
Comparative anatomy
- Homologous structures have same
evolutionary origin, but different structure
and function.
- Analogous structures have similar
structure and function, but different
evolutionary origin.
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Homologies of Religions and Languages
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Homologous Structures
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Homology vs. Analogy
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Homology vs. Analogy
Pterosaur
Bat
Bird
Figure from the National Center for Science Education
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More Evolutionary Deductive
Evidence
Molecular Evidence
- Our increased
understanding of
DNA and protein
structures has led to
the development of
more accurate
phylogenetic trees.
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The Homeodomain, a protein structure found in a large family of
Transcription Factors, and responsible for binding DNA and regulating target genes
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Fig. 1.14
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The 3 Domains of Life on Earth
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Holotype specimen of Juramaia sinensis, Beijing Museum of
Natural History (BMNH) PM1343B.
Z-X Luo et al. Nature 476, 442-445 (2011) doi:10.1038/nature10291
Unifying Themes in Biology
Cell theory
- All living organisms are made of cells, and all living cells come from preexisting
cells.
Molecular basis of inheritance
- Genes, which control living organisms and are passed from one generation to the
next, are found in DNA.
DeoxyriboNucleicAcid
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Unifying Themes in Biology
Cells - information processing systems
- Cells process information stored in DNA as well as information received
from the environment.
Emergent properties
- New properties are present at one level of organization that are not
seen in the previous level.
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.
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Unifying Themes in Biology
Structure and Function
-The function of a molecule is dependent on its structure.
-The structure of a molecule can often tell us about its
function.
The DNA Polymerase III
Beta Subunit (E. coli) with
bound DNA
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