Understanding the Fundamental Properties of Life

1. Life began over 600 million years ago Evolution of -multicellularity, coelom, vertebrae, homeothermy ZOOLOGY—STUDY OF ANIMALS

2. Fundamental Properties of Life • Does Life Have Defining Properties? • What is life?

3. Fundamental Properties of Life • Does Life Have Defining Properties? • What is life? • No simple definition • The history of life shows extensive and ongoing change called evolution • Answer must be based on the common history of life on earth

4. 8 General Properties of Living Systems 1. Chemical Uniqueness: Living systems demonstrate a unique and complex molecular organization • Small molecules are assembled into macromolecules: • Nucleic Acids • Proteins • Carbohydrates • Lipids

5. 8 General Properties of Living Systems • Although living systems are composed of the same kinds of atoms obeying the same fundamental laws of chemistry as nonliving matter, the organizational structure of the macromolecules makes them unique

7. 8 General Properties of Living Systems 2. Complexity and Hierarchical Organization: Living systems demonstrate a unique and complex hierarchical organization • In living systems there exists a hierarchy of levels that includes: Macromolecules Cells Organisms Populations Species

8. 8 General Properties of Living Systems • 3. Reproduction: Living systems can reproduce themselves • At each level of the biological hierarchy living forms reproduce to generate others like themselves: • Genes replicated to produce new genes. • Cells divide producing new cells. • Organisms reproduce, sexually or asexually, to produce new organisms • Populations may fragment to produce new populations • Species may split to produce new species

9. 8 General Properties of Living Systems 4. Possession of a Genetic Program: A genetic program provides fidelity of inheritance • DNA: Long, linear, chain of nucleotides containing genetic information • Sequence of nucleotide bases in DNA determines the order of amino acids in proteins • Genetic Code: correspondence between base sequences in DNA and the sequence of amino acids in a protein

11. 8 General Properties of Living Systems 5. Metabolism: Living organisms maintain themselves by acquiring nutrients from their environments • Metabolic processes include: • Digestion • Energy production (Respiration) • Synthesis of required molecules and structures by organisms

12. 8 General Properties of Living Systems • Metabolism is often viewed as an interaction of destructive (catabolic) and constructive (anabolic) reactions • The most fundamental anabolic and catabolic chemical processes used by living systems arose early in the evolutionary history of life

14. 8 General Properties of Living Systems 6. Development: All organisms pass through a characteristic life cycle • Development describes the characteristic changes that an organism undergoes from its origin to its final adult form

16. 8 General Properties of Living Systems 7. Environmental Interaction: All animals interact with their environments • Ecology: The study of organismal interaction with an environment • All organisms respond to environmental stimuli

18. 8 General Properties of Living Systems 8. Movement: Living systems and their parts show precise and controlled movements arising from within the system • Living systems extract energy from their environments permitting the initiation of controlled movements

19. 8 General Properties of Living Systems • Movements at the cellular level are required for: Reproduction Growth Responses to stimuli Development in multicellular organisms • On a larger scale: Entire populations or species may disperse from one geographic location to another over time

20. Zoology As Part of Biology • Characteristics of Animals: • Multicellular • Eukaryotes: cells contain membrane-enclosed nuclei • Heterotrophs: Not capable of manufacturing their own food and must rely on external food sources • Cells lack cell walls and photosynthetic organelles And most can 5. Reproduce sexually 6. Move

21. Principles of Science • The scientific method may be summarized as a series of steps: • Observation • Question • Hypothesis Formation • Empirical Test • Controlled Experiment Includes at least 2 groups Test Group Control Group • Conclusions Accept or reject your hypothesis • Publications

22. Principles of Science • Hypothesis: • Potential answers to questions being asked • Derived from prior observations of nature or from theories based on such observations • Often constitute general statements about nature that may explain a large number of diverse observations • If a hypothesis is very powerful in explaining a wide variety of related phenomena, it attains the level of a theory

23. Principles of Science • Powerful theories that guide extensive research are called paradigms • The refutement and replacement of a paradigm is known as a scientific revolution • Two major paradigms that guide zoological research: • Darwin’s Theory of Evolution • The Chromosomal Theory of Inheritance