Lecture Notebook. to accompany

Transcription

1 Lecture Notebook to accompany Sinauer Associates, Inc. MacMillan Copyright Cover photograph Ch ien Lee/Minden Pictures. This document may not be modified or distributed (either electronically or on paper) without the permission of the publisher, with the following exception: Individual users may enter their own notes into this document and may print it for their own personal use.

2 1 Principles of Life Each day represents about 150 million years. Life appeared some time around day 5, a little less than 4 billion years ago. First life? Homo sapiens (modern humans) arose in the last 5 minutes of day 30 (around 500,000 years ago). 12 Recorded history covers the last few seconds of day FIGURE 1.1 Life s Calendar (Page 3) To add notes to any page, use Adobe Reader s Text Comment tool (formerly called the Typewriter tool). Requires Adobe Reader 8 or later. The latest version of Adobe Reader can be downloaded free of charge from the Adobe website at 2

3 Chapter 1 Principles of Life 3 Haloferax mediterranei Membrane This prokaryotic organism synthesizes and stores molecules that nourish and maintain it in harsh environments. FIGURE 1.2 The Basic Unit of Life Is the Cell (Page 3) (A) (B) FIGURE 1.3 Photosynthetic Organisms Changed Earth s Atmosphere (Page 4)

4 Chapter 1 Principles of Life 4 Endosymbiotic bacteria became the mitochondria of eukaryotes. Endosymbiotic, photosynthetic bacteria became chloroplasts. Number of known (described) species Estimated total number of living species BACTERIA 10,000 Millions Life Mitochondria Chloroplasts ARCHAEA Plants ,000 1,000 1 million 400, ,000 EUKARYA 80, ,000 1 million Animals 1,300, million 100 million Fungi 100, million FIGURE 1.4 The Tree of Life (Page 5) Atoms Small molecules Large molecules, proteins, nucleic acids Cells Cell specialization Organism Oxygen Carbon Water Methane Colonial organisms Tissues Organs Hydrogen (A) Atoms to organisms Carbon dioxide DNA Unicellular organisms Organ systems Multicellular organism (leopard frog) FIGURE 1.5 Life Consists of Organized Systems at a Hierarchy of Scales (Pages 6 and 7)

5 Chapter 1 Principles of Life 5 Biosphere Population Community Landscape (B) Organisms to ecosystems FIGURE 1.5 Life Consists of Organized Systems at a Hierarchy of Scales (continued) Boxes represent components. Arrows represent processes by which components interact. Component A Interaction between A and B Component B Interaction between B and C Component C FIGURE 1.6 A Generalized System (Page 7)

6 Chapter 1 Principles of Life 6 (A) A cellular-level system Synthesis of Protein T increases the amount of Protein T. Breakdown of Protein T decreases the amount of Protein T. free amino acids in cell Synthesis of Protein T Protein T in cell Breakdown of Protein T breakdown products in cell (B) An organismal-level system Na + in gut from foods Absorption of Na + from gut by gut cells Na + in body fluids Excretion of Na + by kidney cells Na + leaving the body in urine (C) A community-level system Abundance of grass Consumption of grass by voles Number of voles Consumption of voles as food Number of foxes and owls FIGURE 1.7 Organized Systems Exist at Many Levels (Page 8) Positive feedback speeds up an earlier process in a system. Negative feedback slows down the process. Feedback occurs when the rate of an early process is affected by the amount of a later product (C in this case). + Component A Rate of conversion of A to B Component B Rate of conversion of B to C Component C FIGURE 1.8 Feedback Can Be Positive or Negative (Page 8)

7 Chapter 1 Principles of Life 7 In a quantified system, A, B, and C are quantified measures of the amounts or concentrations of the components of the system. A Equation 1 (describes rate of conversion of A to B) B Equation 2 (describes rate of conversion of B to C) C In-Text Art (Page 9) One nucleotide Four distinct nucleotides are the building blocks of DNA. The nucleotides differ in the base they contain (C, G, T, or A). G C A T Strand 1 Strand 2 DNA is made up of two strands of linked sequences of nucleotides. DNA A gene consists of a specific sequence of nucleotides. Gene DNA The nucleotide sequence in a gene contains the information to build a specific protein. Protein FIGURE 1.9 DNA Is Life s Blueprint (Page 9)

8 Chapter 1 Principles of Life 8 This ground-living frog walks across the ground using its short legs and peglike digits (toes). Webbed rear feet are evident in this highly aquatic species of frog. Dyscophus guineti This tree frog has toe pads, which are adaptations for climbing. Pelophylax sp. A different tree frog species has extended webbing between the toes, which increases surface area and allows the frog to glide from tree to tree. Phyllomedusa bicolor Rhacophorus nigropalmatus FIGURE 1.10 Adaptations to the Environment (Page 11)

9 Chapter 1 Principles of Life 9 1. Make observations. 2. Speculate, ask a question. Ask new questions. 3. Form a hypothesis to answer the question. Revise your hypothesis. 4. Make a prediction: What else would be true if your hypothesis is correct? 5. Design and conduct an experiment that uses quantifiable data to test your prediction. Use statistical tests to evaluate the significance of your results. Significant results support hypothesis. Experiment repeated and results verified by other researchers. Results do not support hypothesis. FIGURE 1.11 Scientific Methodology (Page 12) Reexamine the experiment for uncontrolled variables. Investigation FIGURE 1.12 Controlled Experiments Manipulate a Variable Hypothesis Exposure to atrazine during larval development causes abnormalities in the reproductive tissues of male frogs. Method 1. Establish 9 tanks in which all attributes are held constant except the water s atrazine concentration. Establish 3 atrazine conditions (3 replicate tanks per condition): 0 ppb (control condition), 0.1 ppb, and 25 ppb. 2. Place Rana pipiens tadpoles from laboratory-reared eggs in the 9 tanks (30 tadpoles per replicate). 3. When tadpoles have transitioned into adults, sacrifice the animals and evaluate their reproductive tissues. 4. Test for correlation of degree of atrazine exposure with the presence of abnormalities in the gonads (testes) of male frogs. Results Atrophied testes Testicular oocytes Male frogs with gonadal abnormalities (%) Conclusion Atrazine (ppb) 0.0 Control Oocytes (eggs) in normalsize testis (sex reversal) In the control condition, only one male had abnormalities. Exposure to atrazine at concentrations as low as 0.1 ppb induces abnormalities in the gonads of male frogs. The effect is not proportional to the level of exposure. (Page 14) Go to LaunchPad for discussion and relevant links for all INVESTIGATION figures.

10 Chapter 1 Principles of Life 10 Investigation FIGURE 1.13 Comparative Experiments Look for Differences among Groups Hypothesis Presence of the herbicide atrazine in environmental water correlates with gonadal abnormalities in frog populations. Method 1. Based on commercial sales of atrazine, select 4 sites (sites 1 4) less likely and 4 sites (sites 5 8) more likely to be contaminated with atrazine. 2. Visit all sites in the spring (i.e., when frogs have transitioned from tadpoles into adults); collect frogs and water samples. 3. In the laboratory, sacrifice frogs and examine their reproductive tissues, documenting abnormalities. 4. Analyze the water samples for atrazine concentration (the sample for site 7 was not tested). 5. Quantify and correlate the incidence of reproductive abnormalities with environmental atrazine concentrations. Results Male frogs with gonadal abnormalities (%) Atrophied testes Testicular oocytes Atrazine level Not tested Atrazine (ppb) In the seven sites where atrazine was present, abnormalities, including testicular oocytes and atrophied testes, were observed Site 0 Conclusion Reproductive abnormalities exist in frogs from environments in which aqueous atrazine concentration is 0.2 ppb or above. The incidence of abnormalities does not appear to be proportional to atrazine concentration at the time of transition to adulthood. Go to LaunchPad for discussion and relevant links for all INVESTIGATION figures. (Page 15)