Biology Partnership (A Teacher Quality Grant) Classification & Origin October 26, 2013 Nancy Dow Jill Hansen Tammy Stundon Gulf Coast State College Panhandle Area Educational Consortium 5230 West Highway 98 753 West Boulevard Panama City, Florida 32401 Chipley, Florida 32428 850-769-1551 877-873-7232 www.gulfcoast.edu Our Approach Q & A board What is origin of life? How did we get here? How do we know? Florida Next Generation Sunshine State Standards • SC.912.L.15.8 Describe the scientific explanations of the origin of life on Earth. (MODERATE) – (Also assesses SC.912.N.1.3, SC.912.N.1.4, and SC.912.N.2.1.) Benchmark Clarifications – Students will describe scientific explanations of the origin of life on Earth. – Students will identify situations or conditions contributing to the origin of life on Earth. – Students will identify ways in which a scientific claim is evaluated (e.g., through scientific argumentation, critical and logical thinking, and consideration of alternative explanations). – Students will assess the reliability of sources of information according to scientific standards. – Students will identify the criteria that differentiate science from nonscience and pseudoscience. Content Limits – Items may address the conditions required for the origin of life on Earth but may not require specific knowledge of the age of Earth or its eras, periods, or epochs. – Items may assess how contributions of scientists such as Pasteur, Oparin, Miller and Urey, Margulis, or Fox aided in the development of the scientific explanation of the origin of life but will not assess what each scientist contributed. – Items assessing the origin of organic molecules, chemical evolution, and/or eukaryotic cells should be conceptual. – Items may refer to the endosymbiotic theory but may not assess the term in isolation. – Items assessing a scientific claim are limited to the scientific explanations of the origins of life on Earth. Stimulus Attributes None specified Response Attributes Responses in items referring to scientific claims, sources of information, scientific inferences, and identifying what is science should be specific to the context of the item instead of generic statements. Bell Ringer • Big Bang today Millions of years ago versus Billions of years ago…. How to demonstrate to your students the difference. Age example & Becker Bottles Demo How Much is a Billion? • 1,000 seconds = 16.7 minutes • 1 million-s = 16,677 min = 11.6 days • 1 billion-s = 11,574 days = 31.7 years • 1,000 pennies = ~ 88 ounces = 5.5 pounds • 1 million pennies = 5,500 pounds (~1-Suburban) • 1 billion pennies = 2,750 tons (~2 Space Shuttles) Billion Grains of Rice • • • • • • • 200 grains of rice in a teaspoon 9,600 grains of rice in a cup (48 tsp) How many Cups are in a Gallon? 16 cups How many grains of rice are in 16 cups? 9,600 x 16 = 153,600 grains of rice How many gallons would it take to take to equal 1 million grains of rice? • 1,000,000 divided by 153,600 = • 6.5 Gallons = 1 million grains of rice • If 6.5 gallons equal 1 million how many gallons would it take to equal 1 billion? • 6.5 gallons x 1000 = • 6,500 gallons = 1 billion Chemical Evolution (1 billion years) Formation of the earth’s early crust and atmosphere Small organic molecules form in the seas Large organic molecules (biopolymers) form in the seas Biological Evolution (3.7 billion years) Single-cell prokaryotes form in the seas Single-cell eukaryotes form in the seas Variety of multicellular organisms form, first in the seas and later on land First protocells form in the seas Men in Black Earth was very different billions of years ago. • There have been many hypotheses of the origins. • The most widely accepted hypothesis of Earth’s origins is the nebula hypothesis. • It suggests that 4.6 billion years ago, the sun formed from a nebula (a cloud of gas and dust in space) • Over time, most of the material in the nebula pulled together due to gravity. • Over millions of years, repeated collisions of this space debris built up into planets of our solar system. THE EARLIEST LIFE ON EARTH? Fossils of 3.4-billion-year-old cells that may have been among the first living organisms on earth THE OLDEST ROCKS ON EARTH-- THAT WERE FOUND IN GREENLAND--ARE ABOUT 3.8 BILLION YEARS OLD. Recent scientific discoveries possibly link back rocks to 4.4-4.6 b.y.a (in Australia) Early Earth Conditions The early atmosphere differed from that of today – very little water vapor and no free-floating oxygen. Early Earth: Rough conditions. • no ozone layer to block harmful UV radiation • no troposphere to control the Earth’s thermostat Early seas called the “PRIMORDIAL SOUP “— They were filled with chemicals that would later build organic compounds; molecules of life as Suggested by Oparin. 4.4 b.y.a early atm had just a little water vapor, but lots of CO, CO2, H2, N2, NH3 (ammonia), CH4 (methane), H2S . For life to form…. • Group of organized atoms (N, O, C, H, etc.) molecules (proteins, carbohydrates, water) cells (which is the smallest unit of life) Cells 1) reproduce 2) grow and develop 3) respond to stimuli 4) obtain and use energy 5) made up of cell (s) The Earth will need to increase the concentrations of water and oxygen to support the life. Theories of the origin of life • Spontaneous Generation (abiogenesis) – life arises for non-life; old theory that has been disproved. – General experiment with meat 1668 Redi – disproved this common belief but only for large organisms– his experiment: • Still considered what are microorganisms as the ‘vital force of air’ 1864 Pasteur – disproved the entire theory On both macro and micro level….. But still, where did life come from? Life needs water and oxygen! • There are different hypotheses of early cell structure. – iron-sulfide bubbles hypothesis- biological molecules combined in compartments of hydrothermal vent chimneys on the ocean floor. (these compartments acted like the first cell membranes) – lipid membrane hypothesis lipid spheres could form around a variety of organic molecules giving rise to the first true cells. – meteorite hypothesis- amino acids may have arrived on Earth through meteorites or asteroid impacts The Oparin-Haldane Theory of the Origin of Life • According to their theory, life evolved in the oceans during a period when the atmosphere was reducing - containing H2, H2O, NH3, CH4, and CO2, but no free O2. • Organic compounds were synthesized nonbiologically by ultraviolet light energy, which in the absence of an ozone shield would penetrate the upper layers of the ocean. • Without free O2 to oxidize them, these organic molecules would be stable, and would accumulate in a warm, dilute broth that has been nicknamed "Haldane soup.“ • This Oparin-Haldane theory was a remarkably complete blueprint for the ideas still held today. It was especially remarkable because in 1929 virtually none of the biochemical details of the previous chapters were known. THE UREY-MILLER EXPERIMENT In 1953, Stanley Miller and Harold Urey developed a simple four-step experiment that demonstrated how complex organic molecules could have arisen in earth’s early environment.—IN THE ‘PRIMORDIAL SOUP’ OR AS DARWIN CALLED IT---THE ‘WARM LITTLE POND’— conditions had to be just right for these organic molecules to form. THE UREY-MILLER EXPERIMENT 1 2 They created a model of the chemicals present in the "warm little pond" with the gases H2, CH4 (methane), and NH3 (ammonia) Why does this sound familiar? The atmosphere was subjected to sparks, to simulate lightning. 3 The atmosphere was cooled so that any compounds in it would rain back down into the water. 4 They examined the water, looking for organic molecules. Produce energy in the absence of oxygen! Electrical charge 2 1 3 Cool 4 Then they did the experiment again: Added N2 & CO2. Results: ATP - Implication? Cytosine & Uracil Implication? RNA came before DNA! Heat No life was created. 1st experiment results: 5 different amino acids, urea, and lactic acid Implications? Sidney Walter Fox • The production of amino acids from inorganic molecules – 1964 Dr. Sidney Fox based his experiments off of the information found in the Miller-Urey experiment. • The creation of proteinoids – He demonstrated that amino acids could spontaneously form small peptides. These amino acids and small peptides could be encouraged to form closed spherical membranes, called proteinoid microspheres, which show many of the basic characteristics of 'life • The assembly of proteinoids into microspheres What is the origin of life? Even though scientifically the origin is uncertain, scientist do know that the earliest life form had to have had: 1. Heterotrophic – cloudy atm, too much radiation for photosynthesis or chemosynthesis 2. Anaerobes – live w/o oxygen in the atm (Earth was acidic/plate disruptions) 3. Others? Single-celled, prokaryotic, asexual binary fission And for life to rapidly evolve, oxygen was needed to first develop the ozone layer (UV filter) and then to gather in concentration in the troposphere for aerobic respiration What developed to allow Oxygen to increase in concentration? Ancient form of photosynthesis – used H2S instead of H2O Stromatolites (cyanobacteria) changed that by utilizing the little H2O vapor which released the oxygen; led to modern day photosynthesis. O2 ozone layer Oxygen in troposphere more life, BOOM! How Do Scientists Know the Contents of the Ancient Atmosphere and Age? Most kids will say Carbon-14; but that is really for fossils and we are discussing a time billions of years before fossils! • Ice Sheets can trap in gasses • Radiometric dating – the breakdown of an isotope Radiometric Dating Remember the proton is the defining characteristic of an element! Overtime the element decays, thus converting into another element How much Time to convert? 1.25 billion years! What is this called? Decay of Candium Species Timeline Activity Earth in 24 hours Modern humans (Homo sapiens) appear about 2 seconds before midnight Age of reptiles Insects and amphibians invade the land Age of mammals Recorded human history begins 1/4 second before midnight midnight Origin of life (3.6–3.8 billion years ago) First fossil record of animals Plants begin invading land noon Evolution and expansion of life 24 hour clock perspective 32 One Year Perspective The Football Field Perspective Endosymbiosis Theory • Dr. Lynn Margulis was the first to claim the endosymbiont nature of mitochondria and chloroplasts with a handful of conclusive evidence Evidence of Endosymbiosis theory • Chloroplast and Mitochondria – Double membranes • Outer membrane is of eukaryotic origin • Inner membrane is of prokaryotic origin – Single loop of DNA – Reproduce by binary fission – Have ribosomes of prokaryotic origin – About the same size as prokaryotes Video Living Fossil - Establishes the understanding of who determines extinction Analysis of structures – possible missing link Reinforces reading and discussion Nice transition into Natural Selection Ask the students if this organism reminds them of any cartoons characters….. Scientist to Know! Understanding Geological Time- Berkley Video tutorials - history of earth, origin of life; Urey and Miller EOC review from Pace HS – check these answers! Found wrong answers with their scientist section – it is a pdf so I could not make changes. Otherwise, still a very good source/format Virtual lab Classifying organism into Kingdoms Exploring Life’s Origins Interactive Geologic Time Scale I Interactive Geologic Time Scale II The Evolution of Organelles Follow up •Q & A •Post Test