BIOLOGY 101

1. BIOLOGY 101 • Scientific Study of Life • Introduction to Biology

2. 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 pollinationand help disperse the resulting seeds

3. Flying foxes are becoming an endangered species, partly because of habitat destruction

4. 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

5. 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)

6. ECOSYSTEM LEVELEucalyptus forest • Ecosystems include: • all the organisms in an area, which make up a community • interbreeding organisms of the same species, a population • At the top of life’s hierarchy is the ecosystem COMMUNITY LEVELAll organisms ineucalyptus forest POPULATION LEVELGroup of flying foxes ORGANISM LEVELFlying fox Brain Spinal cord ORGAN SYSTEM LEVELNervous system ORGAN LEVELBrain Nerve TISSUE LEVELNervous tissue CELLULAR LEVELNerve cell MOLECULAR LEVELMolecule of DNA Figure 1.1

7. organ systems • organs • tissues • cells • molecules ECOSYSTEM LEVELEucalyptus forest • Organisms are made up of: COMMUNITY LEVELAll organisms ineucalyptus forest POPULATION LEVELGroup of flying foxes ORGANISM LEVELFlying fox Brain Spinal cord ORGAN SYSTEM LEVELNervous system ORGAN LEVELBrain Nerve TISSUE LEVELNervous tissue CELLULAR LEVELNerve cell MOLECULAR LEVELMolecule of DNA Figure 1.1

8. 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

9. They propose a hypothesis • They make deductions leading to predictions • They then test the hypothesis by seeing if the predictions come true • In hypothesis-driven science, scientists use the “scientific method”

10. 1.3 With the scientific method, we pose and test hypotheses Observation • The main steps of the scientific method Question Hypothesis Prediction Test does notsupport hypothesis; revise hypothesis or pose new one Test supports hypothesis; make additional predictions and test them Test: Experiment oradditionalobservation Figure 1.3A

11. starts with a general explanation which leads to predictions for specific observations supporting it • Deductive reasoning is used in testing hypotheses

12. 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. • Experiments designed to test hypotheses must be controlled experiments

13. 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.

14. Case study: spider mimicry Figure 1.3C Pounce rate (% of trials in which spider jumped on fly) Control group(untreated flies) Experimental group(wing markings masked) Figure 1.3D

15. Another test of the spider mimic hypothesis: wing transplants Number of stalk andattack responsesby spiders Wingmarkings Wingwaving Normalspidermimic Mimic withmimic wing transplant Mimic withhousefly wing transplant Housefly withmimic wing transplant Normalhousefly Figure 1.3E Controls Experimentals

16. Modern Biology is based on; • The Cell Theory • The Theory of Evolution by Natural Selection • Gene Theory • Homeostasis

17. The Cell Theory: • All cells come from pre-existing cells • All organisms are composed of one or more cells.

18. 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

19. Figure 1.8 Evolution

20. Tree of Life

21. Domain Bacteria • Most classification schemes group organisms into three domains: • Domain Archaea Figure 1.4A, B

22. Domain Eukarya Figure 1.4C-F

23. Cells

24. Cells and Organelles

25. Macromolecules

26. 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

27. Each species has its own nucleotide sequence • DNA is made of chemical units called nucleotides Figure 1.5B

28. DNA

29. Central Dogma

30. Chromosomes

31. Cell Cycle

32. Mitosis

33. Order and regulation • Growth and development • Use of energy from the environment • Response to environmental stimuli • Ability to reproduce • Evolutionary change • The genetic information in DNA underlies all of the features that distinguish life from nonlife

34. Molecular Basis of Inheritance

35. Scale

36. 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

37. Connective Tissue Fibroblasts

38. Epithelial tissue Bile duct mouth From The Cell 2nd ednASM & Sinauer

39. Blood Granulocyte Lymphocyte Monocyte

40. Nervous tissue from http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Nervous/Nervous.htm

41. Muscle Smooth muscle Skeletal muscle Cardiac muscle From http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/h_frame7.html

42. 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

43. The theory of natural selection explains the main mechanism whereby all species of organisms change, or evolve (1) Population with varied inherited traits (2) Elimination of individuals with certain traits (3) Reproduction of survivors Figure 1.6B

44. 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

45. Figure 1.14 Bacterial Colonies

46. 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

47. Figure 1.15 Electron Micrograph of Saccharomyces cerevisiae

48. 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

49. Figure 1.17 Caenorhabditis elegans

50. 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