Introductory Zoology PowerPoint Presentation

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Introductory Zoology BIO 2 Monday & Wednesday 9:30-10:45 Monday & Wednesday 11:00-1:50 Nancy Wheat nwheat@hartnell.edu

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The Science of Zoology Zoology is the study of animal life. Zoologists strive to understand: The origin of animal diversity. How animals perform basic life processes. How they are able to inhabit various ecosystems.

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The Uses of Principles Principles of modern zoology are derived from: Laws of physics and chemistry Scientific method Because life shares a common evolutionary origin, principles learned from the study of one group often pertain to other groups as well.

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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.

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Properties of Life Chemical Uniqueness – Living systems demonstrate a unique and complex molecular organization.

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Chemical Uniqueness Living organisms assemble large molecules – macromolecules – that are more complex than molecules found in nonliving matter. Same chemical laws apply. Four categories of biological macromolecules: Nucleic acids Proteins Carbohydrates Lipids

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Chemical Uniqueness These 4 groups differ in their: Components Types of bonds holding them together Functions Macromolecules evolved early in the history of life. Found in every form of life today.

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Chemical Uniqueness Proteins are made up of 20 different amino acid subunits. Enormous variability allows for the diversity of proteins and consequently of living forms. Nucleic acids, carbohydrates & lipids are also organized in a way that gives living systems a large potential for diversity.

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Properties of Life Complexity and Hierarchical Organization – Molecules are organized into patterns in the living world that do not exist in the nonliving world.

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Complexity and Hierarchical Organization New characteristics can appear at any level of organization – emergent properties. Emergent properties depend upon the characteristics found at lower hierarchical levels – to some extent. The development of spoken language requires hearing. But, many different languages have arisen.

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Properties of Life Reproduction – Living systems can reproduce themselves!

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Reproduction Genes replicate themselves forming new genes. Cells divide to produce new cells. Organisms reproduce to produce new organisms. Populations can split to form new populations. Even species may split to produce new species - speciation.

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Reproduction Heredity and variation are present at all of these levels. Heredity – faithful transmission of traits from one generation to the next. Variation – production of differences among the traits of individuals. Result: offspring are similar to – but not exactly like parents.

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Properties of Life Genetic program – provides fidelity of inheritance.

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Genetic Program Genetic information is coded in DNA. DNA is a long chain of nucleotides – a sugar, phosphate + nitrogenous base (A, C, G, & T). The sequence of nucleotides codes for the order of amino acids in the protein specified. The genetic code

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Genetic Program The genetic code is universal among living organisms from bacteria through humans. Supports the concept of a single origin of life.

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Properties of Life Metabolism – Living organisms maintain themselves by acquiring nutrients from their environments.

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Metabolism Metabolism includes all of the chemical reactions occurring within an organism. Digestion Respiration Synthesis of molecules and structures

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Metabolism Metabolism includes destructive (catabolic) and constructive (anabolic) reactions. These reactions include synthesis of the 4 types of macromolecules as well as cleavage of bonds to recover the energy stored there. Physiology – the study of complex metabolic functions.

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Properties of Life Development – All organisms pass through characteristic stages in their life cycle.

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Development Development includes characteristic changes an organism passes through from its beginning (usually as a fertilized egg) through adulthood.

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Development Metamorphosis – transformation from one life stage to another. Tadpole to frog Caterpillar to butterfly

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Properties of Life Environmental interaction – Living organisms interact with their environments.

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Environmental Interaction Ecology is the study of this interaction between organisms and between organisms and their environment.

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Properties of Life 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.

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Movement Movements at the cellular level are required for: Reproduction Growth Responses to stimuli Development in multicellular organisms

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Movement On a larger scale: Entire populations or species may disperse from one geographic location to another over time. Movement of nonliving matter: Not precisely controlled by the moving objects. Often involves external forces.

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Physical Laws First Law of Thermodynamics – Energy can not be created or destroyed, but can be transformed. Energy enters our system as sunlight. The energy in the sunlight is transformed into chemical bonds through photosynthesis. When these bonds are broken, the energy is released.

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Physical Laws Second Law of Thermodynamics – Physical systems proceed toward a state of entropy or disorder. Energy is required to maintain the complex organization in living organisms.

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Physical Laws The complex molecular organization in living cells is attained and maintained only as long as energy fuels the organization. Survival, growth, and reproduction of animals require energy that comes from breaking complex food molecules into simple organic waste.

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Zoology As Part of Biology Biology is the study of living organisms. Zoology focuses on the Kingdom Animalia. In this course we’ll be studying the diversity of animals on our planet, how they are related, how they work, and how they interact with each other.

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Zoology As Part of Biology Animals originated in the Precambrian seas over 600 million years ago. Characteristics of Animals: 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

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The Nature of Science

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The Nature of Science Science is a way of asking questions about the natural world. Guided by natural laws (physical & chemical). Questions must be testable! Always open to new evidence. Falsifiable.

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The Nature of Science We can ask different types of questions about animals. Questions about proximate (or immediate) causes. Questions about ultimate causes.

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Proximate Cause Questions about the proximate (or immediate) causes that underlie the functioning of a biological system can be studied using the “scientific method”. How does an animal perform its metabolic, physiological or behavioral functions? Molecular biology Cell biology Endocrinology Developmental biology Community ecology

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Scientific Method This simplified flow diagram of the scientific method shows the important components involved in a scientific study. Observations Hypothesis Experiment/ Observations Conclusion Scientific Theory

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Scientific Method First is the observation phase, where new observations are made. This is also the time where previous data are examined. Next, a hypothesis is formulated to attempt to explain the available data and observations. A hypothesis must be testable!!!

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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.

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Scientific Method The hypothesis is then tested through a series of experiments and/or observations. These experiments and observations must be repeatable! The factual information resulting from these experiments and observations are called data. An important part of an experiment is the control, which is a replicate set up exactly like the experiment, except it does not have the factor being tested.

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Scientific Method Scientists can then draw a conclusion based on the data. The conclusion may involve accepting or rejecting the initial hypothesis. Further experiments may require an adjustment to the conclusions. Hypotheses are said to be supported, but not proven.

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Scientific Method New hypotheses are generated from the conclusions, and the process starts again. A theory results when a group of related hypotheses are supported by many experiments and observations. Theories are the ideas that scientists are MOST SURE OF! Theory of gravity Theory of natural selection

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Scientific Method The previous model is very simplified and the result is too linear. The ‘activity model’ for the process of scientific inquiry shows the more complex interactions that are really involved. Harwood, W. S. 2004. A new Model for Inquiry: is the Scientific Method Dead? Journal of College Science Teaching. 33(7): 29-33.

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Example Experiment Observation: Light moths more common in clean areas, dark moths more common in polluted areas. Prediction 1: Moths better able to survive if they match their background. Supported by experimental studies with predatory birds. Prediction 2: If polluted areas are cleaned, light moths should become more common (as lichen grows on trees).

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Ultimate Cause Some scientists ask questions about ultimate cause. The comparative method is used more than experimentation. Comparative biochemistry Molecular evolution Comparative cell biology Comparative anatomy Comparative physiology Phylogenetic systematics

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Ultimate Cause In evolutionary biology, characteristics of molecular biology, cell biology, organismal structure, developmental biology and ecology are compared. Resulting patterns of similarity can be used to test hypotheses of relatedness.

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Evolution and Heredity

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Evolution and Heredity 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

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Theory of Evolution Charles Darwin – On the Origin of Species by Means of Natural Selection, 1859.

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Theory of Evolution Five related theories: Perpetual change Common descent Multiplication of species Gradualism Natural selection

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Theory of Evolution Perpetual Change – The world and the organisms living in it are always changing. Supported by the fossil record. The properties of organisms undergo transformation across generations throughout time. Theory upon which the remaining 4 are based.

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Theory of Evolution Common Descent – All forms of life descended from a common ancestor through a branching of lineages. Life’s history has the structure of a branching evolutionary tree, known as a phylogeny Serves as the basis for our taxonomic classification of animals Descent with modification. Supported by molecular work.

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Theory of Evolution Multiplication of Species – New species are produced by the splitting and transforming of older species. Gradualism – Large differences result from the accumulation of small changes over long periods of time. Occasionally, changes can happen more quickly.

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Theory of Evolution Natural Selection – Differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment.

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Theory of Evolution Natural selection requires: Variation within the population. This variation must be heritable. Organisms with a particular variation will have more offspring. Over time, these successful variations will spread through the population.

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Adaptation Natural selection explains why organisms are constructed to meet the demands of their environments. Adaptation results when the most favorable variants accumulate over evolutionary time.

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Unity in Diversity All vertebrate forelimbs share an underlying structure utilizing the same parts, but have evolved a diverse array of adaptations, as seen in the wing of a bat, the flipper of a whale, & a human arm.

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Mendelian Heredity Darwin knew that some traits were heritable, but he didn’t have an understanding of the mechanism of heredity.

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Mendelian Heredity Gregor Mendel performed experiments on garden peas leading to an understanding of how chromosomal inheritance works.

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Mendel’s Peas Mendel chose peas to study inheritance because they possess several contrasting traits without intermediates. Green vs. yellow peas Tall vs. short plants Wrinkled vs. smooth peas Purple vs. white flowers

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Mendel’s Peas The peas can self-fertilize or outcross. Mendel could control who the parents were. Mendel always started with true-breeding parents. E.g. self-fertilized white flowered parents always produced white flowered offspring.

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Mendel’s Peas He could cross true breeding white with true breeding purple – this is the parental generation. Resulting in all purple offspring – this is the F1 generation.

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Mendel’s Peas Allowing the hybrid F1 generation to self pollinate gives the F2 generation with 3 purple: 1 white offspring. He kept careful quantitative records that allowed him to find patterns.

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Contributions of Cell Biology Microscopes allowed scientists to study the production of gametes (eggs & sperm). They could watch the movement of chromosomes. Result: the chromosomal theory of inheritance. Heritable information is contained on chromosomes.