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BIOLOGY 101 • Scientific Study of Life • Introduction to Biology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Life in the Trees • The lives of gray-headed flying foxes are closely entwined with the lives of the eucalyptus trees that form their habitat – Eucalyptus trees provide food and roosting sites for the flying foxes – Flying foxes aid in eucalyptus pollination and help disperse the resulting seeds Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Flying foxes are becoming an endangered species, partly because of habitat destruction Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings THE SCOPE OF BIOLOGY • Biology is the scientific study of life • Interactions between different kinds of organisms affect the lives of all – Recall the example of flying foxes and eucalyptus trees Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 1.1 Life’s levels of organization define the scope of biology • A structural hierarchy of life, from molecules to ecosystems, defines the scope of biology • An ecosystem consists of: – all organisms living in a particular area – all nonliving physical components of the environment that affect the organisms (soil, water) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • At the top of life’s hierarchy is the ecosystem ECOSYSTEM LEVEL Eucalyptus forest • Ecosystems include: – all the organisms in an area, which make up a community – interbreeding organisms of the same species, a population Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings COMMUNITY LEVEL All organisms in eucalyptus forest POPULATION LEVEL Group of flying foxes ORGANISM LEVEL Flying fox Brain ORGAN SYSTEM LEVEL Nervous system ORGAN LEVEL Brain Spinal cord Nerve TISSUE LEVEL Nervous tissue CELLULAR LEVEL Nerve cell MOLECULAR LEVEL Molecule of DNA Figure 1.1 • Organisms are made up of: – organ systems ECOSYSTEM LEVEL Eucalyptus forest – organs – tissues – cells – molecules COMMUNITY LEVEL All organisms in eucalyptus forest POPULATION LEVEL Group of flying foxes ORGANISM LEVEL Flying fox Brain ORGAN SYSTEM LEVEL Nervous system ORGAN LEVEL Brain Spinal cord Nerve TISSUE LEVEL Nervous tissue CELLULAR LEVEL Nerve cell MOLECULAR LEVEL Molecule of DNA Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 1.1 THE PROCESS OF SCIENCE 1.2 Scientists use two main approaches to learn about nature • In discovery science, scientists describe some aspect of the world and use inductive reasoning to draw general conclusions – Example: scientists have described how newborn flying foxes cling to their mother’s chest for the first weeks of life Figure 1.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • In hypothesis-driven science, scientists use the “scientific method” – They propose a hypothesis – They make deductions leading to predictions – They then test the hypothesis by seeing if the predictions come true Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 1.3 With the scientific method, we pose and test hypotheses Observation • The main steps of the scientific method Question Hypothesis Prediction Test does not support hypothesis; revise hypothesis or pose new one Figure 1.3A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Test: Experiment or additional observation Test supports hypothesis; make additional predictions and test them • Deductive reasoning is used in testing hypotheses – starts with a general explanation which leads to predictions for specific observations supporting it Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Experiments designed to test hypotheses must be controlled experiments • Control groups must be tested along with experimental groups for the meaning of the results to be clear. – Controls are used to filter out other explanations. A control is a replica of the experiment with the independent variable omitted. The dependent variable is what is measured (like how much a plant grows from day to day). The control in human drug tests is generally a sugar pill called a placebo. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The scientific method • In order to eliminate human bias most drug tests are conducted in a double blind fashion. In a double blind experiment researchers and patients do not know whether the pill given is the drug or the placebo until the trial is over. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Case study: spider mimicry Pounce rate (% of trials in which spider jumped on fly) Figure 1.3C Control group (untreated flies) Figure 1.3D Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Experimental group (wing markings masked) Number of stalk and attack responses by spiders • Another test of the spider mimic hypothesis: wing transplants Wing markings Wing waving Normal spider mimic Figure 1.3E Mimic with mimic wing transplant Controls Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Mimic with housefly wing transplant Housefly with mimic wing transplant Experimentals Normal housefly Modern Biology is based on; • The Cell Theory • The Theory of Evolution by Natural Selection • Gene Theory • Homeostasis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The Cell Theory: • All cells come from pre-existing cells • All organisms are composed of one or more cells. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings EVOLUTION, UNITY, AND DIVERSITY 1.4 The diversity of life can be arranged into three domains • Grouping organisms by fundamental features helps make the vast diversity of life manageable for study • Scientists classify organisms into a hierarchy of broader and broader groups Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 1.8 Evolution Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Tree of Life Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Most classification schemes group organisms into three domains: – Domain Bacteria – Domain Archaea Figure 1.4A, B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings – Domain Eukarya Figure 1.4C-F Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cells Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cells and Organelles Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Macromolecules Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 1.5 Unity in diversity: All forms of life have common features • All organisms share a set of common features, signs of unity in life’s vast diversity – All are made of cells – All have DNA as their genetic blueprint • These orchids show the variety possible within one species Figure 1.5A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • DNA is made of chemical units called nucleotides • Each species has its own nucleotide sequence Figure 1.5B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings DNA Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Central Dogma Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Chromosomes Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cell Cycle Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Mitosis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The genetic information in DNA underlies all of the features that distinguish life from nonlife – Order and regulation – Growth and development – Use of energy from the environment – Response to environmental stimuli – Ability to reproduce – Evolutionary change Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Molecular Basis of Inheritance Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Scale Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cells and Tissues • In human body, there are more than 200 different kinds of cells. • These cells make up five main type of tissue • Epithelial tissue • Connective tissue • Blood • Nervous tissue • Muscle Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Connective Tissue Fibroblasts Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Epithelial tissue Bile duct mouth From The Cell 2nd ednASM & Sinauer Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Blood Granulocyte Lymphocyte Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Monocyte Nervous tissue from http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Nervous/Nervous.htm Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Muscle Smooth muscle Skeletal muscle Cardiac muscle From http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/h_frame7.html Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 1.6 Evolution explains the unity and diversity of life • Charles Darwin is a central figure in biology • He synthesized the theory of evolution by natural selection – A theory in science is a comprehensive idea with broad explanatory power • Evolution is the core theme of biology Figure 1.6A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The theory of natural selection explains the main mechanism whereby all species of organisms change, or evolve Figure 1.6B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings (1) Population with varied inherited traits (2) Elimination of individuals with certain traits (3) Reproduction of survivors Model Organisms: E. coli • Uses medium containing glucose, aa, salts, vitamins; Divide every 20 mins • Genome contains 4.6 million base pairs; about 4000 genes • Clonal populations can be selected; those resistant to penicillin Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 1.14 Bacterial Colonies Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Yeast: S. cerevisiae • Eukaryotic • Genome contains 12 million base pairs of DNA; 6000 genes; 16 linear chromosomes • Can be grown in the lab; replicate every 2 hours grown in colonies • Can be used to understand DNA replication, transcription, RNA processing, protein sorting, regulation of cell division Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 1.15 Electron Micrograph of Saccharomyces cerevisiae Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Worm: C. elegans • Multicellular • Understanding development • Genome contains 100 million bps of DNA; 19000 genes • Contain 959 cells (somatic); 1000-2000 germ cells • Lineage tracing; genes of development and differentiation Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 1.17 Caenorhabditis elegans Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Plant: Arabidopsis • Plant molecular biology and development • Genome contains 120 million bp of DNA, 15000 genes. • Can be grown in pots; mutants are available • Comparisons of cellular mechanisms between plants and animals Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 1.19 Arabidopsis thaliana Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Vertebrates • Xenopus laevis: frog • Danio rerio: fish Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 1.20 Eggs of the Frog Xenopus laevis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 1.21 Zebrafish Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Model Organisms and Applications Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Model Organisms and Applications Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Model Organisms and Applications Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Model Organisms and Applications Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Model Organisms and Applications Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Model Organisms and Applications Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Model Organisms and Applications Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Model Organisms and Applications Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 1.22 Defects in pigmentation (piebaldism) due to mutations in a gene regulate migration of melanocytes Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Humans and Flies Alike (Pax6 gene) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Table 1.1 Prokaryotic and Eukaryotic Cells Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Table 1.2 DNA Content of Cells Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings