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Origin of Life – Ch 14

“…sparked by just the right combination of physical events & chemical processes…”. Origin of Life – Ch 14. Focus of Chapter 14. Matter, Energy, and Organization

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Origin of Life – Ch 14

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  1. “…sparked by just the right combination of physical events & chemical processes…” Origin of Life – Ch 14

  2. Focus of Chapter 14 • Matter, Energy, and Organization • Life on Earth arose from nonliving matter in a process that required the input of energy. New life-forms evolved from the earliest life-forms, requiring energy input and resulting in highly complex organisms.

  3. Assessing Prior Knowledge 1. Name the elements common to all organic compounds. • Carbon • Hydrogen • Oxygen

  4. Name the four types of organic compounds found in living thing and state a major role in each. • Carbohydrates - • Proteins • Lipids • Nucleic acids

  5. Bacteria Archae- bacteria Protista Plantae Fungi Animalia 0 Cenozoic Colonization of land by animals Mesozoic Paleozoic 500 Appearance of animals and land plants First multicellular organisms 1000 PROTEROZOIC Oldest definite fossils of eukaryotes 1500 2000 Appearance of oxygen in atmosphere PRECAMBRIAN Millions of years ago Oldest definite fossils of prokaryotes 2500 3000 ARCHEAN 3500 Molten-hot surface of earth becomes cooler 4000 4500 Formation of earth The evolutionary tree of life can be documented with evidence. The Origin of Life on Earth is another story…

  6. Ch 14-1 Biogenesis • Objectives • Define spontaneous generation; list observations that led people to think that life could arise from nonliving things. • Summarize Redi’s and Spallanzani’s experiments testing spontaneous generation. • Describe Pasteur’s experiment and how it disproved the hypothesis of spontaneous generation.

  7. Terms to know • Biogenesis - all living things come from other living things. • Spontaneous generation – an early and now disproved hypothesis that stated that living organisms develop from nonliving material.

  8. What is Life? • First we have to define LIFE… • organized as cells • respond to stimuli • regulateinternal processes • homeostasis • use energy • metabolism • Develop and Grow • change & mature within lifetime • reproduce • heredity • DNA / RNA • adaptation & evolution

  9. The Origin of Life is a Hypothesis • Extraterrestrial Origin • Was the original source of organic (carbon) materials comets & meteorites striking early Earth? • Testable • Spontaneous Abiotic Origin • Did life evolve spontaneously from inorganic molecules? • testable

  10. In the 17th century it was widely believed that living things could arise from nonliving things in a process called spontaneous generation. • Explained why: • Maggots appeared on rotting meat. • Fish appeared in ponds that had been dry the previous season. • Today we believe in biogenesis, where all living things come from other living things.

  11. Redi’s Experiment • 1668 • Showed that rotting meat kept away from flies would not produce new flies. • Maggots appeared only on meat that had been exposed to flies.

  12. Spallanzani’s Experiment • 1700’s • Showed that microorganisms would not grow in broth when its containers was heated and then sealed. • Seems to indicate that microorganisms that cause food spoilage do not arise from spontaneous generation but, rather are carried in air.

  13. Pasteur’s Experiment • Used a variation of Spallanzani’s design to prove that mo’s are carried in the air and do not arise by spontaneous generation.

  14. 14-2 Earth’s History • Objectives • Describe the conditions of early Earth. • Describe the production of organic compounds in the Miller-Urey apparatus. • Summarize the possible importance of cell-like structures produced in the laboratory.

  15. Conditions on early Earth • Reducing atmosphere • water vapor (H2O), CO2, N2, NOx, H2,NH3, CH4, H2S • lots of available H & its electron • no free oxygen • Energy source • lightning, UV radiation, volcanic low O2 = organic molecules do not breakdown as quickly What’s missingfrom thatatmosphere?

  16. Lerman Bubble Model

  17. Electrodes discharge sparks (lightning simulation) Water vapor Mixture of gases ("primitive atmosphere") Condenser Water Condensed liquid with complex, organic molecules Heated water ("ocean") Origin of Organic Molecules • Abiotic synthesis • 1923Oparin & Haldane propose reducing atmosphere hypothesis • 1953Miller & Urey test hypothesis • formed organic compounds • amino acids • adenine CH4 H2 NH3

  18. http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter26/animation_-_miller-urey_experiment.htmlhttp://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter26/animation_-_miller-urey_experiment.html

  19. It’s ALIVE! Stanley Miller University of Chicago produced -amino acids -hydrocarbons -nitrogen bases -other organics

  20. Bubbles…Tiny bubbles… Origin of Cells (Protobionts) • Bubbles  separate inside from outside  metabolism & reproduction • Microspheres – Primitive cell membranes made of proteins • Coacervates – droplets of linked sugars and amino acids

  21. Key Events in Origin of Life • Key events in evolutionary history of life on Earth • Sun Formation 5 bya • Earth Formation 4.5 bya • Life originated 3.5–4.0 bya

  22. Radioactive Carbon Dating The process that allows scientists to age objects based on the amount of radioactive material in the object. Radioactive Isotopes are unstable elements that breakdown over time. Radioactive decay is the converting of radioactive material into a stable format through the loss of energy. Half-Life is the amount of time it takes for one half of a given amount of isotope to become stable.

  23. Prokaryotes • Prokaryotes dominated life on Earth from 3.5–2.0 bya 3.5 billion year old fossil of bacteria modern bacteria chains of one-celledcyanobacteria

  24. Oxygen atmosphere • Oxygen begins to accumulate 2.7 bya • reducing oxidizing atmosphere • evidence in banded iron in rocks = rusting • makes aerobic respiration possible • Cyanobacteria - photosynthetic • algae

  25. ~2 bya First Eukaryotes • Development of internal membranes • create internal micro-environments • advantage: specialization = increase efficiency nuclear envelope endoplasmicreticulum (ER) plasma membrane infolding of theplasma membrane nucleus DNA cell wall plasma membrane Prokaryotic cell Prokaryotic ancestor of eukaryotic cells Eukaryotic cell

  26. Endosymbiosis • Evolution of eukaryotes • origin of mitochondria • engulfed aerobic bacteria, but did not digest them • mutually beneficial relationship internal membrane system aerobic bacterium mitochondrion Endosymbiosis Eukaryotic cell with mitochondrion Ancestral eukaryotic cell

  27. Eukaryotic cell with mitochondrion Endosymbiosis • Evolution of eukaryotes • origin of chloroplasts • engulfed photosynthetic bacteria, but did not digest them • mutually beneficial relationship photosyntheticbacterium chloroplast mitochondrion Endosymbiosis Eukaryotic cell with chloroplast & mitochondrion

  28. Lynn Margulis Theory of Endosymbiosis • Evidence • structural • mitochondria & chloroplasts resemble bacterial structure • genetic • mitochondria & chloroplasts have their own circular DNA, like bacteria • functional • mitochondria & chloroplasts move freely within the cell • mitochondria & chloroplasts reproduce independently from the cell

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