Welcome to the Second Semester

1. Welcome to the Second Semester Spring 2007 (Jan. 29-June 14)

2. Changes for the Semester • Online Quizzes: • Will be assigned but not collected or graded until June 1 • Either printout your results for each quiz and save (or) submit online. • Summaries for submitted quizzes will be available (check) • Scoring changes: 80% or higher = 2 pts. 79% & lower = 1 pt. Not done: = 0 • Hall Passes (get two): Extra points @ end of Sem. if not used • Participation grade: still 25 pts • Preparedness will be checked more frequently on the seating chart.

3. Important Issues for 2nd Semester • Number of Instructional days before tests: 60 • IB & AP Testing starts on May 2. • Two major projects will be going on at beginning • Seed Germination Research (Journal & collecting data) • Plant Adaptation Project @ CSU Fullerton Arboretum • Four Major Tests and a Final will be given • One quiz in the middle of each unit will be given • Online/CD Quizzes will be still assigned.

4. Critical Dates for 2nd Semester • Introduction & Beginning of Semester Jan 29 & 30 • Intro. Seed Germination Project: begins Jan 31 • Intro. Plant Adaptation Project (arboretum) Feb. 2 • Field trip to CSU Fullerton Arboretum Feb. 9 • Exam #1: Plants Feb. 28 • Seed Germination Journal & Data Collected Mar. 1 • Plant Adaptation project Due Mar. 5 • Exam #2: Nervous, Mus., Behavioral & Senses Mar. 29 • Exam #3: Animal Systems April 27 • AP Biology Test May 14 • IB (SL) Tests May 14 & 15 • Exam #4: Ecological Principls May 25 • Final Exam June 8

5. Key Topics for Second Semester • Plant Unit: Ch. 26, 29,30, 35-39,10 • Animal Systems I: Ch. 48, 49, 51 • Animal Systems II: Ch. 42-43, 44-47 • Ecology: Ch. 50, 52-54 • Overall Diversity of Life • Rominov Mystery of Anastasia • Debates & Presentations of Endangered Species

6. Introductory Questions #1 • How long ago is the Earth thought to have formed? How did we come up with this time? • List the four main stages that have been hypothesized as to how life could have began? (pg. 513) • Name the molecules thought to exist in the early atmosphere? Why were these molecules chosen? • What does it mean when we say that this early atmosphere was a “reducing” atmosphere? • What is the significance of Miller’s experiment in the 1950’s? • What are protobionts and microspheres? (google) • Where can Stomatolites be found? What are they composed of? (index & google) • What is the predominant thought of how Polymerization might of occurred? • Was the first organisms thought to be heterotrophs or Autotrophs? Explain.

7. The Origin of Life(Chapter 26)

8. Three Proposed Models • Pre-Biotic Soup Hypothesis (Oparin & Haldane) **proposed in 1920’s** • Iron-Sulfur Hypothesis (Hydrothermal vents) • Seeded Meteorite impact

9. The Origin of LifeSpontaneous generation vs. Biogenesis (Pasteur) • The 4-stage Origin of life Hypothesis: • 1- Abiotic synthesis of organic monomers • 2- Polymer formation • 3- Origin of Self-replicating molecules • 4- Molecule packaging (“protobionts”)

10. Early History of life • Solar system: 12 billion years ago (bya) • Earth: 4.5 bya • Life: 4.5 to 4.0 bya • Prokaryotes: 3.5 to 2.0 bya (stromatolites) • Oxygen accumulation: 2.7 bya ( photosynthetic cyanobacteria) • Eukaryotic life: 2.1 bya • Multicelluar eukaryotes: 1.2 bya • Animal diversity: 543 mya (Burgess Shale) • Land colonization: 500 mya

11. Early History of life

12. Chemical Evolution & Formation of Macromolecules • Solar System: formed approx. 12 billion years ago • Earth is Approx. 4.6 Billion Years ago • Early Atmosphere was thought to be composed of: • CO2 Water Vapor • CO H2 • N2 NH3 (ammonia) • H2S CH3 (methane) • Reducing Atmosphere (molecule forming) • First Life form originated approx. 3.8 billion years ago

13. Organic monomers/polymer synthesis • Oparin (Rus.)/Haldane (G.B.) hypothesis (primitive earth): volcanic vapors (reducing atmosphere) with lightning & UV radiation enhances complex molecule formation (no O2) • Miller/Urey experiment (1950’s): water, hydrogen, methane, ammonia all 20 amino acids, nitrogen bases, & ATP, DNA, and RNA were formed

14. How Polymerization could Occur? • Clay was thought to be a possible site for polymerization • Binds well to organic molecules • Contains Zinc, iron, nickel, etc serving as a catalyst • Has been shown to occur experimentally

15. Formation of the first Cells • Began as molecular aggregates (microspheres & protobionts) • Divide often (binary fission) • Grow larger in size • Maintain a level of homeostasis internally • Produce electrical potential across surfaces • Absorbs materials from the surface (selective permeability) • Catalytic actvity

16. Molecular Replication • Usually involves DNA, RNA and proteins • All can form on clay surfaces • Self-replication common with DNA & RNA • Which formed first? DNA or RNA?

17. Molecular Replication • Most hypothesize that RNA was the first to form. Why? • RNA is a versatile molecule and: • Able to function both as an enzyme & substrate • Single stranded and easily forms H-bonds • Has catalytic properties • Can direct protein synthesis • Folds on itself and from various shapes

18. Abiotic Genetic Replication • First genetic material • Abiotic production of ribonucleotides • Ribozymes (RNA catalysts) • RNA “cooperation” • Formation of short polypeptides (replication enzyme?) • RNA~ DNA template?

19. Molecular cooperation led to the first cells controlled by RNA • Oldest fossilized cells widely accepted (2 bya) • Layers of Microorganisms & sediment called: Stromatolites First cells thought to be anaerobic using glycolysis as its metabolic pathway Heterotrophs → Photoautotrophs → Aerobes—Euk’s (O2 increases) (endosymbiotic theory)

20. The Major Lineages of Life

21. Figure 15.1

22. Key Fossil finds & Extinction Points • Ediacaran: oldest known fossils (600 mya) Australia • Burgess Shale: Cambrian explosion British Columbia • Permian Extinction: 90% of all marine life • Cretaceous Period: end of dinosaur fossils