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

Fundamental Properties of Life Does Life Have Defining Properties? What is life?

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

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

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

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 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

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

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

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

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

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

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

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

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

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

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

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