Bio 178 Lecture 1

Biology: The Study of Life

Reading

• Chapter 1

Quiz Material

• Questions on P18

• Chapter 1 Quiz on Text Website (www.mhhe.com/raven7)

Outline• Definition of Biology• Properties of Life• Hierarchical Organization• Scientific Method• Unifying Themes of Biology

What is Biology?

The scientific study of organisms (living beings).

Properties of Life

• Basic characteristics of living organisms– Cellular Organization– Order– Sensitivity– Growth, Development, and Reproduction– Energy Utilization (metabolism)– Evolutionary Adaptation– Homeostasis

Hierarchical Organization• Cellular level

– Atoms– Molecules– Macromolecules– Organelles– Cells

• Organismal level– Tissues– Organs– Organ systems– Organisms

Hierarchical Organization

• Populational level– population

• species– biological community

» ecosystem

– Emergent properties• Novel properties that arise at each higher level

The Scientific Method:The Scientific Method:The Hypothetico-Deductive Method

Hypothesis - Tentative answer to a question (educated guess)

Deductive - Deductive Reasoning

Reasoning

•Deductive Reasoning (Predictions)–Apply general principles to predict specific results

Eg. “If organisms are composed of cells (H1) & humans are organisms (H2), then humans are composed of cells (P)”.

•Inductive reasoning–Use specific observations to construct general principles

Stages of a Scientific InvestigationObservation

Question

Hypothesis(es)

Prediction(s)

Controlled Experiment

Conclusion

How to Write QHPsExample 1: The laptop stops working.

O: The laptop is not working

Q: Why is the laptop not working?

H:

Example 2 (include a control): Asprins get rid of headaches.

Q: Do asprins truly get rid of headaches?

H: If asprins truly get rid of headaches, the headaches will clear FASTER if asprin is taken than if it is not.Controlled Experiment:Predictions:Conclusions:

A Few Definitions

• An experiment is used to test a hypothesis, and/or eliminate one or more multiple hypotheses.

• In a controlled experiment, all variables but one are kept constant in the experimental. In the control that variable is unaltered.

• A theory is a hypothesis supported by a wealth of scientific evidence ( is a generally accepted principle).

Scientific ProcessOQ H P Controlled Experiments Conclusions

Manuscript preparation for publication

Peer Review

Publication

Replication by other scientists

Acceptance by the scientific community

Example of the Development of a Theory: Evolution

Accepted “Belief” in 1831: Species have been specifically created and are unchangeable over time.

Darwin’s Evidence: Fossil record

Geographical Distribution

Islands

Darwin’s Theory: Evolutionary changes occurring by the mechanism of natural selection are responsible for the diversity of life on earth.

Unifying Themes of Biology

• Cell theory• Molecular basis of inheritance• Evolutionary change - Diversity• Evolutionary conservation - Successful

structures are conserved

Cell Theory

Robert Hooke (1665): Discovered cells

Schleiden and Schwann (1839): “All living things are composed of cells”

Modern Cell Theory

All living organisms are made of cells, and all living cells come from other living cells.

Unifying Themes in Biology

Unifying Themes of Biology• Molecular basis of inheritance

– DNA encodes genes which make-up and control living organisms. Heredity is dependent on the faithful copying of the cell’s DNA into daughter cells.

• Evolutionary conservation– Some fundamentally important characteristics of earlier organisms are preserved and passed on to future generations.

Eg. Histones

Unifying Themes of Biology• Evolutionary change

– Life-forms have evolved varying characteristics to adapt to varied environments. This has resulted in incredible diversity.