7 mins urey miller expt https://youtube/watch?v=NNijmxsKGbc

1. 7 mins urey miller expt https://www.youtube.com/watch?v=NNijmxsKGbc

2. Chapter 26 The Tree of Life (Evolutionary History)

3. What you need to know: • A scientific hypothesis about the origin of life on Earth. • The age of the Earth and when prokaryotic and eukaryotic life emerged. • Characteristics of the early planet and its atmosphere. • How Miller & Urey tested the Oparin-Haldane hypothesis and what they learned. • Methods used to date fossils and rocks and how fossil evidence contributes to our understanding of changes in life on Earth. • Evidence for endosymbiosis. • How continental drift can explain the current distribution of species. • How extinction events open habitats that may result in adaptive radiation.

4. ANIMALS Plants Prokaryotes Multicellular A Brief History of Life Eukaryotes

8. Early conditions on Earth

9. Formation of Earth • 4.6 billion years old • Hadeon Eon • Formation of Moon • 4.5 BYA • What was early Earth like? (we think) • Hot: Due to formation of the Earth • Violent: due to the formation of the solar system • Toxic: Lots of nasty gases in the atmosphere (CO2, NH3, SO2, H2O) inorganic molecule (non living world) • NO OXYGEN GAS

10. Heavy Bombardment (we think) • About 4 BYA (600 million years after the formation of the solar system) • Comes from being bombarded by comet and asteroids • Evidence: cratering still visible on geological dead bodies of the inner solar system such as moon and Mercury. • Something really big blasted off the moon • Atmosphere was either reducing or neutral (atmosphere is oxidizing)..favoring increasing chemical complexity

11. End of Heavy Bombardment: first life (~4 BYA) • HOW DID LIFE ARRIVE (ORIGIN OF LIFE) • 4 STEPS • 1. Formation of Biological Molecules (monomers and polymers) • 2. Accretion of proto-cells, membrane develops (before prokaryotic cells) • 3. Development of an information molecule • 4. Reproduction

12. Primordial soup • Introduced by Soviet biologist Alexander Oparin to propose a theory of the origin of life on Earth during a gradual chemical evolution of molecules that contain carbon in primordial soup

13. Synthesis of Organic Compounds on Early Earth • Oparin & Haldane: • Early atmosphere = H2O vapor, N2, CO2, H2, H2S methane, ammonia • Energy = lightning & UV radiation • Conditions favored synthesis of organic compounds - a “primitive soup”

14. Step 1. Formation of Biological Molecules Miller & Urey (1953): • Tested Oparin-Haldane hypothesis • Simulated “Early Earth” conditions in lab • Produced amino acids & organic molecules

15. Other experiments have since demonstrated biological molecule formation in • Volcanoes • Asteroids (in space) • Comets (in space) • Asteroid/comet impacts

16. Step 2. Accretion of proto-cells • Collections of biological molecules, packing of macromolecules into protobionts have been investigate extensively in labs • Proto-cells have lipid protein membrane and carry on energy metabolism • Coacervates proposed by Oparin as possible protocell • Tiny spherical droplet, lipid molecule held together by hydrophobic forces from surrounding liquid • Protobionts can • Self assemble • Primitive metabolism • Absorb & excrete biological molecules

17. 2. Development of Proto-cells

19. Protocells & Self-Replicating RNA

23. Step 3. Development of an Information molecule • RNA World • Hypothesis that proposes the RNA was the first information molecule. • Based on that RNA has both information storage and catalytic functions • Ribozymes: RNA enzymes • Artificial evolution of RNA molecules in vitro has been demonstrated in labs • Or were proteins first to arrive?? Or both??

26. DO NOT WRITE!!!

27. 3. Information Molecule Evolution

28. 4 Reproduction – self replication firstOnce protocell was capable of reproduction it became a true cell and bio evolution beganFew things to keep in minda. It could have taken hundreds of million of years to happenb. Once it starts, evolution creates a positive feedback loop that leads to increasing efficiency and complexity of lifec. Maybe it happened somewhere else, first (panspermia)

29. The panspermia hypothesis states that the "seeds" of life exist all over the Universe and can be propagated through space from one location to another. Some believe that life on Earth may have originated through these "seeds".

30. Hydrothermal vents • First discovered in 1977 • form at locations where seawater meets magma • Hot springs o the ocean floor Black smokers A venting black smoker emits jets of particle-laden fluids. The particles are predominantly very fine-grained sulfide minerals formed when the hot hydrothermal fluids mix with near-freezing seawater. These minerals solidify as they cool, forming chimney-like structures. “Black smokers” are chimneys formed from deposits of iron sulfide, which is black. “White smokers” are chimneys formed from deposits of barium, calcium, and silicon, which are white. Underwater volcanoes at spreading ridges and convergent plate boundaries produce hot springs known as hydrothermal vents

31. Origin of Life: hydrothermal vents is birthplace of life pores in the hydrothermal vent chimneys that act like tiny pumps powered life giving chemical reactions of the earliest proto cells

32. Dominated life from 3.5-2.0 BYA Prokaryote Cell- Draw and label

33. Structure of bacteria (unicellular) • 1. Cell wall, Cell membrane, Cytoplasm same as other cells • 2.DNA - a single, circular chromosome located in the cytoplasm. • 3.Capsule - a thick, gel-like, protective coating. • 4.Pili - short, hair like protein structures on the surface of some bacteria that help them stick to host cells. • 5.Flagella - long protein structures that turn to propel some bacteria cells.

34. Prokaryotes • Dominated life from 3.5-2.0 BYA • 2 domains: • Archae – live in extreme environoment, resemble first primitive cells • Bacteria- diverse and most widespread

35. Archaebacteria A subkingdom of bacteria, they survive in environments similar to those found on the young Earth: hot springs, sea vents releasing sulfide-rich gases, boiling muds around volcanoes, that sort of place. Example: Methanogens, Extreme Halophiles, Thermoacidophiles Eubacteria contains the bacteria commonly referred to as germs contains most of the world's bacteria Examples: Escherichia coli Archaebacteria and Eubacteria (Domains)

36. Archaebacteria • 1. Methanogens:“methane-makers”Use only CO2, H and N to produce energy to live, and as a result give off methane gas. Live in swamps, marshes, gut of cattle, termites, etc. Methanococcus jannaschii, isolated from the deep sea Alvin probe, was the first Archaean whose genome was sequenced. Methanogens are decomposers; and can be used in sewage treatment. Methanogens may someday be used to produce methane as fuel!2. Extreme Halophiles: “salt lovers”Require an environment as salty or even10x saltier than ocean water. Some prefer up to 30% salt concentrations! These bacteria live in the Dead Sea, the Great Salt Lake, salt evaporation ponds. • 3. Extreme Thermophiles: “heat / cold lovers”Prefer temperatures above 60�C (up to 110�C for hyperthermophiles!) or near or below freezing. (Some thermophiles will die at roon temperature). Thermophiles ive in hot sulfur springs, Yellowstone Park, deep sea hydrothermal vents “black smokers”, geothermal power plants. Also live in ocean waters around Antarctica, under the polar ice caps, etc. Thermus aquaticus and Pyrococcus furiosis and two species.

37. Bacteria • 1. Proteobacteria: Enteric bacteria like E. coli, Salmonella typhus, Legionella, Heliobacter pylorii (cause of many ulcers), Neisseria gonorrhea (cause of gonorrhea). These bacteria are very closely related to eukaryotic mitochondria.2. Cyanobacteria: Photosynthetic ‘blue-green’ bacteria = produce O2 gas. Over 2 billion years ago, these bacteria made the O2 rich atmosphere in which we live!!! These bacteria are very closely related to eukaryotic chloroplasts.3. Eubacteria: Clostridium (tetanus, botulism), Bacillus, mycoplasma (walking pneumonia).4. Chlamydias: Parasites: Giardia, Chlamydia (STD)5. Spirochaetes: Spiral bacteria: cause syphilis, Lyme disease

38. Peptidoglycan- a polymer that is composed of polysaccharide and peptide chains and is found especially in bacterial cell walls — called also mucopeptide, murein

41. Bacteria reproduction • 1. Binary fission (asexual) - the DNA replicates and then the cell pinches inward and splits in two. Horizontal acquisition of genetic information (transfer of genetic material between differ sources) • 2. Conjugation - two cells exchange DNA across a bridge formed between the cells. New material replaces old material in the cell. • 3. Transformation: bacteria take in plasmids (circular DNA) from the environment • 4. Transduction: bacteria acquire new DNA from a phage (virus)

42. Conjugation Transduction

43. shape Cell wall and ribosome Binary fission

47. The anaerobic metabolic processes of the heterotrophs released carbon dioxide into the atmosphere, which allowed for the evolution of photosynthetic autotrophs, which could use light and CO2 to produce their own food. • The autotrophs released oxygen into the atmosphere. For most of the original anaerobic heterotrophs, oxygen proved poisonous. The few heterotrophs that survived the change in environment generally evolved the capacity to carry out aerobic respiration. Over the subsequent billions of years, the aerobic autotrophs and heterotrophs became the dominant life-forms on the planet and evolved into all of the diversity of life now visible on Earth.

48. Evolution of Metabolism “Heterotroph Hypothesis”: Glycolysis (O2 not required) → Photosynthesis → Aerobic Cellular Respiration.

49. Photosynthesis starts ~ 3.5 BYA • Heterotroph Hypothesis • Prior to photosynthesis, life at other life (was heterotrophic) • Cyanobacteria: only photosynthetic bacterial cells to produce oxygen • MODERN FOSSIL

50. Stromatolites: large colonies of cyanobacteria (rock with blue green algaeModern Fossils