Introduction to BiologyLecture 1Fall 2008

What is Biology?

Biology –

The scientific study of life

• What is science?

• What is life?

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Life

What is life??

Fig. 1.3

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Themes in Biology

1. Cells are an organism’s basic units of structure and function

• The lowest level of structure that can perform all activities required for life

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Fig. 1.8

Themes in Biology

2. Continuity of life is based on heritable information in the form of DNA

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Fig. 1.10

Themes in Biology

3. Structure and Function are correlated at all levels of biological organization

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See Fig. 1.4

Themes in Biology

4. Emergent properties• The whole is greater than the sum of its parts• New properties emerge with each step upward

in the hierarchy of life

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Themes in Biology

• Reductionism & Systems Biology

Fig. 1.12

Fig. 1.10

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Themes in Biology

5. Organisms interact with their environments, exchanging matter and energy

Fig. 1.5

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Themes in Biology6. Feedback mechanisms regulate biological

systems• Negative & Positive feedback

Fig. 40.8

Fig. 40.16

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Themes in Biology

6. Evolution is the theme that unifies all biology

“Nothing in biology makes sense except in the light of evolution”

- Theodosius Dobzhansky

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See Fig. 1.22

Themes in Biology

Diversity and Unity – the dual nature of life

• All life unified by basic properties

• Vast diversity of biological forms

Globally - ~1.8 million species

~10,000 birds~ 4629 mammals~ 8240 reptiles~ 900,000 insects (named)~ 300,000 vascular plants~ 20,000 fish

Washington State~ 466 birds~ 139 mammals~ 25 reptiles~ 3200 plants~ 211 fish (Puget sound)

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Fig. 1.14

Themes in Biology

• Diversity and Unity

See Fig. 1.15

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The Theory of Evolution by Natural Selection

Evolution:

- a genetically based change in the characteristics of a population over time.

Explains the diversity and similarity of organisms; how organisms have come to be adapted to a wide range of environments.

Process = Natural selection

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The Theory of Evolution by Natural Selection

1. Individuals within a population vary in traits.2. At least some of the variation must be heritable

so it can be passed onto offspring (DNA).3. In every generation, more offspring are

produced than can survive (overproduction and competition).

4. Unequal reproductive success - Survival and reproduction of individuals is not random.

Outcome of process: Population’s characteristics will change over time = Evolution will occur.

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The Theory of Evolution by Natural

Selection

Fig. 1.20

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Artificial Selection16

Why study biology??

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What is Science?

What is Science?

• A way of knowing, based on inquiry

• A search for an understanding of the natural world

• Attempts to discover order in nature and to use that knowledge to make predictions about what should happen in nature

• Exploring and explaining the world

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What is Science?

Science seeks natural causes for natural phenomena

Discovery Science• Descriptive science• Based on observations & measurements• Inductive reasoning – generalization that

summarizes a large number of observations• “bottom-up

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What is Science?

Science seeks natural causes for natural phenomena

Hypothesis-driven Science• Asking questions and seeking explanations• Scientific Method• Deductive reasoning – moves from general to more

specific• “top-down”

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The Scientific Method

Make observations

Formulate a hypothesis

Test hypothesis: Experimental design and

data collection

Draw conclusions

Analyze & interpret data

Prompts questions

Makes a testable prediction

New observations or controlled experiments

Supports or refutes hypothesis?

Publish results

Scientific hypothesis: A proposed explanation; An educated guess that attempts to explain an observed pattern.Prediction: A statement of what you should be able to measure or observe in nature if the hypothesis is correct.

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The Scientific Method

• Skepticism

• Peer Review

• Reproducibility

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Scientific Theory

Common usage – Theory:(2) Abstract reasoning, speculation.(4) An assumption based on limited information or

knowledge, a conjecture.The American Heritage Dictionary, 3rd Ed. 1992

Scientific Theory:Well-tested and widely accepted

scientific hypothesis

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Scientific Uncertainty

Quantitative Data• Precise and easily compared• Good benchmark for measuring changeStatistics• Important in both planning and evaluating

scientific studies• Sample size, number of replications importantProbability• Measure of how likely something is• High degree of scientific certain, 95% probability

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Dry Falls & the Missoula Floods

J. Harlen Bretz

1923 - Geology of channeled scablands in eastern WA due to flooding on a massive sale

J.K.Barndt, 2004

1940 – evidence of a huge lake in Montana that had emptied rapidly

1950 - Aerial photography – Bretz’s work finally accepted

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Regrowth of insulin producing beta cellsScientific American, Dec 2006

2001 Dr. Denise Foustman published work on regrowth of insulin producing beta cells to help cure diabetes

“Consensus” science believed this was not possible

2006 – 3 groups reported in Science that Dr. Foustman’s work had been reproduced

The scientific method – a case study

Observations:• Two snakes look alike• Predators rarely attack eastern coral snake• Eastern coral snake is poisonous, scarlet king

snake is not

Fig. 1.25

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The scientific method – a case study

Question:• Does the mimicry protect the Scarlet king

snake?

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Fig. 1.25

The scientific method – a case study

Hypothesis:• The king snake mimicry of the coral snake helps

protect it from predators in areas where the two species ranges overlaps

Prediction:• Predators will attack snakes with rings of bright

red, yellow and black less frequently than plain snakes

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Fig. 1.25

The scientific method – a case study

Experiment:• Create two types of

artificial snakes– Colored– Plain

• Record how many attacks occur on each type

Results:• Support hypothesisConclusion:• Mimicry reduces the

amount of predation on the Scarlet king snake where the two ranges overlap

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Fig. 1.27