Chapter One Themes in the Study of Life

1. Chapter OneThemes in the Study of Life

2. Characteristics of Life • Life can’t be summed up into a simple, one-sentence explanation • How do you know that a tree is alive and a rock is not? • All living organisms share certain characteristics • Do you remember what some of these are? Reproduce Contain DNA Adapt to environment Grow and develop Made up of cells Have definite lifespan Utilizes energy Responds to stimuli

3. Levels of life • Life is organized into many structural levels. • Biological structural levels build upon the level below it • cells  • tissues  • organs  • systems  • Individual organism  • populations  • communities  • ecosystems  • Biosphere *And cells of course are made up from even smaller parts.

4. Each Level of Biological Organization Has Emergent Properties Continued • Order is all around us. Notice the pattern and order in this sunflower. • Emergent properties within these levels manifest themselves as a result of dynamic and unique interactions between components

5. Understanding Biological Organization and its Many Levels is Fundamental to the Study of Life • Scientists cannot fully explain a higher level of order from a critical analysis of it parts- • For example: what good is the handle of a hammer without the head? • Holism = disrupting a living system interferes with the meaningful explanation of its processes • But, biological structural levels build upon the level below it, so scientists cannot critically analyze living systems without taking them apart • Reductionism = reducing complex systems to simpler components that are more manageable to study

6. Cells are an Organism’s Basic Units of Structure and Function • The Cell Theory = all living things consist of cells & cells come from other cells • Prokaryotic cells = bacteria / NO true nucleus • Eukaryotic cells = all other organisms / membrane- bound nucleus and endomembrane system

7. In order for a species to continue, organisms must reproduce. DNA makes it possible for the heritable information to be passed on. • DNA - deoxyribonucleic acid • Encoded biological instructions • Substance of genes • Units of inheritance • DNA structure • Long chain made of four nucleotides • Adenine, cytosine, guanine, and thymine • Specific sequential arrangements encode the precise information in a gene

8. Structure and Function are Found at all Levels • DNA encodes a message which dictates the growth and development of the organism • Each cell, organelle, organ, etc. has its own function or duty to perform. • In multicellular organisms, genes are turned on or off in order to specialize the functions of the cells • Form fits function • Analyzing a biological structure clues us to what it does and how it works • Knowing function of a structure provides insight about its construction

9. Understand your subject or specimen • Cells may be the units of organisms but it is the organism that is the unit of life • It is not enough to merely learn what parts make up an organism, but how it grows, interacts, lives, and responds. • Questions to ask about any organism to be studied: • What kind of organism is it? • Where does it live? • How does it acquire nutrients and other resources from the environment? • How is the organism equipped for its way of life?

10. Diversity and Unity • Nearly 2 million species of living things have been identified, but it is estimated there are between 5 - 30 million total species on Earth • ~260,000 plants • ~50,000 animals • ~750,000 insects • Everything has its own niche and purpose in life (diversity and uniqueness), but every living creature needs interaction and support to serve a greater purpose (unity)

11. Taxonomy • With so many types of organisms, a system of classification was necessary • Carolus Linnaeus • Bionomial nomenclature • Taxonomy - naming and classifying species • Kingdom • Phylum • Class • Order • Family • Genus • Species

12. Figure 22-1(1)Page 422 KINGDOM Animalia PHYLUM Chordata CLASS Mammalia

13. Figure 22-1(2)Page 422 ORDER Carnivora FAMILY Felidae GENUS Felis SPECIES Felis catus

14. 6 Kingdom vs. Domains • The six kingdom system of taxonomy categorizes organisms based on cell structure and nutrition • The domain system on the other hand is based on molecular differences • There are 3 domains: • Domain Archaebacteria - contains the archaea kingdom • Domain Eubacteria - contains the eubacteria kingdom • Domain Eukarya - contains kingdoms animalia, protista, fungi, and plantae • *Phylogeny will be discussed when we get to evolution unit

15. Figure 22-2Page 423 Domain Eubacteria (bacteria) Domain Archaea Domain Eukarya The three domains Common ancestor of all living organisms

16. Kingdoms • There are 6 Kingdoms: • Archaea - extreme bacteria; more related to euks • Eubacteria (Monera) - typical bacteria; prokaryotic; peptidoglycan cell walls • Protista - single-celled, aquatic, euk • Fungi - multi-celled; euk, decomposers • Plantae - photosynthetic; euk; multi-celled • Animalia - consumers; euk; multi-celled; 9 phyla

17. Figure 22-3Page 424 Eubacteria Archaebacteria Protista Plantae Protista Animalia Fungi Common ancestor of all eukaryotes The six-kingdom system of classification Common ancestor of all living organisms

18. Bacteria • We’ll study in depth during microbiology and DNA technology

19. Protista • Protists produce 70% of our oxygen, but not all of them are photosynthetic • Vary in size, structure, mode of locomotion, and reproduction • Endosymbiont Theory: the accepted belief is that mitochondria and chloroplasts originated from symbiotic relationships between early protists and bacteria • Chloroplasts - from photosynthetic prokaryotes • Mitochondria - from aerobic prokaryotes

20. Divided into 8 major groups: • Excavates, opisthokonts, discicristates, alveolates, heterokonts, cercozoa, amoebozoa, and plants • NO- you don’t need to memorize these • The plant category also includes plants and algae • Opisthokonts include members of the animal kingdom and fungi kingdom as well • too confusing of a system

21. Fungi • Most are filamentous; made up of hyphae forming an aggregation called mycelium • Most have cell walls of chitin • Most produce by spores (produced sexually or asex) • 5 phyla are identified (but only 4 true phyla exist) • Chytridiomycetes (most primitive) -only fungi with flagella • Zygomycetes - black bread molds • Ascomycetes - sac fungi (yeasts, mildews, colored molds, morels and truffles) • Basidiomycetes - mushrooms, rust, smut, and puff balls

22. Some fungi play an important ecological role • Mycorrhizae - a type of fungus which decomposes organic material in soil • Benefit plants by increasing their absorptive surface area • Roots supply fungus with sugars, amino acids, and other organic substances • Scientists have measured movement of organic materials from one tree species to another without with

23. Plants • You’ll learn everything you ever wanted to know about plants before we do photosynthesis in a few weeks.

24. Animalia • Animals can be classified according to: • body symmetry - radial or bilateral symmetry or asymmetrical • body cavities: coelomates, acoelomates, pseudocoelomates • Coelom : a fluid-filled cavity lined with mesoderm • evolutionary relationships based on molecular data (DNA, rRNA, and Hox genes)

25. Animal Phyla • 1. Porifera - sponges • Aquatic, mostly marine, typically asymmetrical, multicellular but do not have tissues, regenerative capabilities • 2. Cnidarians - hydras, anemones, coral, jellyfish • Radially symmetrical, stinging cells called nematocysts • Diploblastic (only 2 germ layers)

26. Animal Phyla • Acoelomates: • 3. Platyhelminthes - flatworms (flukes, tapeworms) • No body cavity, bilaterally symmetrical, simple nervous system with ganglia • Triploblastic (endoderm, mesoderm, ectoderm)

27. Animal Phyla • Pseudocoelomates: • 4. Nematodes - round worms (hookworms, pinworms, Trichina) • All parasitic, lack a circulatory system, covered by cuticle, false body cavity between mesoderm and endoderm • Triploblastic (endoderm, mesoderm, ectoderm)

28. Animal Phyla • Coelomates: • I - Protostomes • 5. Molluska - squid, snails, clams, oysters • Soft body (usually covered with a shell), foot for locomotion, visceral mass contains body organs, reduced coelom, mantle secretes shell (if present), open circulatory system (except in cephalopods - octopus, squid, nautilus), triploblastic • 6. Annelida - segmented worms (earthworm & leech) • Segmentation, setae, closed circulatory system, triploblastic

29. Animal Phyla • Coelomates: • I - Protostomes • 7. Arthropoda - crustaceans, trilobites, centipedes, arachnids, insects • Exoskeletons, paired, jointed appendages, open circulatory system, nervous system of brain, ladder-like nerve cords and often compound eyes • Aquatic arthropods have gills while terrestrial arthropods have book lungs or trachea • Triploblastic (endoderm, mesoderm, ectoderm)

30. Animal Phyla • Coelomates: • II - Deuterostomes • 8. Echinodermata - sea stars, sea lilies, crinoids, sand dollars • Larval stage is bilaterally symmetrical and adult form is radially symmetrical • Nerve net, no excretory organs, endodermis, calcareous plates covered by epidermis, tube feet • Triploblastic (endoderm, mesoderm, ectoderm)

31. Animal Phyla • Coelomates: • II - Deuterostomes • 9. Chordata - vertebrates and invertebrates • At some point in life cycle, all chordates have: • Notochord (flexible supporting rod), dorsal hollow nerve cord, pharyngeal slits, and post anal tail • Coelomates with bilateral symmetry, endoskeleton, closed circulatory system with ventral heart • Triploblastic (endoderm, mesoderm, ectoderm)

32. Animal Phyla • A closer look at vertebrates: • 2 pairs of appendages, closed circulatory system with ventral heart, vertebral column of bone or cartilage, anterior cranium, paired kidneys, complete digestive tract with large digestive glands • Divided into 3 classes of fish (osteichthyes, chondrichthyes, agnatha) and 4 classes of tetrapods (amphibians, reptiles, birds, mammals)

33. Germ Layers • We’ve used the term triploblastic, but what does it mean? • 3 germ or embryonic layers: • Ectoderm - becomes outer covering and nervous sytem • Mesoderm - becomes most internal organs • Endoderm - becomes lining of the gastrointestinal tract

35. Quantifying Biology • Biology is the study of any and/or all of these living organisms we just mentioned • Biology does not only involve observations, but includes quantifying, manipulating, and analyzing data in order to draw conclusions • Review the Scientific Method: • Observations, Problem/Question, Hypothesis, Experiment and Data Collection, Analysis and Conclusions, Repetition and Sharing • Let’s focus briefly on manipulating and interpreting data

36. Data Collection • All data collected should be accurately measured or counted • Should also be recorded carefully and neatly • Data tables should be done with ruled lines and with appropriate titles and units

37. Statistical Analysis • Correctly manipulating data enables scientists to demonstrate significance of data and to validate claims • When you learn of a claim that a scientist is making, don’t you want to know what the supporting data is?

38. Statistics Terminology • Mean = arithmetic average (sensitive to outlying data) • Median = the value that splits the number of data entries in half (not sensitive to outlying data) • Range = the spread of the data from least to greatest • Standard deviation = a calculated value indicating how much the data varies around the mean value • Error bar = vertical reference lines on graphical distribution of data that illustrates points of std deviations

40. To calculate Standard Deviation manually: • Take EACH data point and subtract the mean value • Square each of these values and add them up • Divide this sum by (the number of data entries minus 1) • Then, take the square root of the answer • The result is the Standard Deviation and is denoted with a +/- sign because it falls on either side of the mean value

41. Standard Deviation using the TI Calculators: • Hit <STAT> and <1> to get to the lists screen • In the L1 column, enter your data • Hit <STAT> again • Choose CALC and then 1-Var Stats • Hit <ENTER> • It gives you the mean, the sum of the values, the sum of the squared differences, and the standard deviation (Sx) • (If you scroll down, it also gives you the min and maximum values and the median)

42. t-test = a test used to deduce the significance of the difference between two sets of data • On your TI Calculator: • Hit <STAT> and <EDIT> to enter your lists in column L1 and column L2 • Hit <STAT> again and scroll over to <TESTS> • Choose <4> for two sample T test • Make sure the two column heading appear from your data • Scroll down and choose calculate • The t value and df (degrees of freedom) are given • Now, use your table to determine acceptance

43. Correlation • When a correlation exists between two sets of data, this does not establish that there is a causal relationship between the two variables being examined