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The Origin of Life I.The Early Ideas  Spontaneous generation  Nonliving material can produce life  Disprove  Francesco Redi  Used maggots in covered.

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Presentation on theme: "The Origin of Life I.The Early Ideas  Spontaneous generation  Nonliving material can produce life  Disprove  Francesco Redi  Used maggots in covered."— Presentation transcript:


2 The Origin of Life

3 I.The Early Ideas  Spontaneous generation  Nonliving material can produce life  Disprove  Francesco Redi  Used maggots in covered and uncovered jars  Louis Pasteur  Used curved flasks with heated broth

4 I.The Early Ideas A. Francesco Redi  1668  Rotting meat kept away from flies would not produce flies  Maggots only on meat exposed to flies  Eggs laid on meat

5 I.The Early Ideas B. Louis Pasteur  Mid- 1800s  Used curve-necked flasks  Microorganisms were prevented from entering the flask  Curved necks broken, broth became cloudy with microorganims

6 I.The Early Ideas Biogenesis  All living things come from other living things  Louis Pasteur  Completely disproved spontaneous generation

7 II.The Modern Ideas  Alexander Oparin  Life began in the oceans  Energy from sun + lightning+ Earth’s heat = simple compounds

8  Stanley Miller and Harold Urey  Used Oparin’s hypothesis to setup experiment  Conditions of early earth II.The Modern Ideas

9  Water vapor, ammonia, methane, hydrogen  Sent electric current through  Cooled gases, collected liquid  Produced amino acids, sugars, and others II.The Modern Ideas

10 III.Formation of Protocells  Sidney Fox  Produced protocells  Large, ordered structure, enclosed by a membrane  Carries out some life activities (growth and division)  Heated amino acids

11 IV. The First True Cells  Prokaryotes evolved from a protocell  Heterotrophs (obtained food)  Anaerobic  Archaebacteria  Prokaryotic  Autotrophs  Deep-sea vents and hot springs

12  Photosynthesizing prokaryotes  Increased oxygen in atmosphere  2.8 bya  Eukaryotes evolved from prokaryotes  Ozone provided protection IV. The First True Cells

13 V. Endosymbiotic Theory  Bacteria (cyanobacteria) and chloroplasts resemble each other in size and photosynthesize  Chloroplast and mitochondria contain separate DNA, reproduce separately, have own ribosomes

14 V. Endosymbiotic Theory  In Conclusion:  Aerobic prokaryotes evolved into modern mitochondria  Photosynthetic cyanobacteria evolved into chloroplasts  plant


16  Draw, Label, and Describe the Endosymbiotic Theory.  May use text book  Pages 427-428 Endosymbiotic Theory

17 Charles Darwin British naturalist 1809-1882 Founder of modern evolutionary theory

18 I. Darwin  Naturalist on HMS Beagle in 1831  collected, studied, stored biological specimens throughout South America and South Pacific  published “On the Origin of Species by Natural Selection” in 1859 HMS Beagle

19 I. Darwin  Traveled to Galapagos Islands  Species of reptiles, insects, birds, flowering plants were unique to the islands but similar to species elsewhere

20 Galapagos Islands


22 I. Darwin  Found that individuals struggled for existence  Competition for:  Food  Space  Predators  shelter Food Predators Space Shelter Finding mates

23 I. Darwin Artificial Selection Breeding organisms with specific traits in order to produce offspring with identical traits Dogs Horses

24 I. Darwin Natural Selection  Mechanism for change in populations  Organisms with favorable variations for a particular environment survives, reproduce, and pass these variations on to the next generation English moths

25 I. Darwin Natural Selection  Alfred Russel Wallace  Wrote similar ideas to Darwin  Jointly presented  Origin of Species written

26 Adaptations: Evidence for Evolution

27 II. Structural Adaptations A. Mimicry  Enables one species to resemble another.  Example: Bee orchid, yellow jackets

28 B. Camouflage  Organisms blend with its surroundings  Example: flounder Praying mantis Frog Flounder II. Structural Adaptations

29 III. Physiological Adaptations  Changes in an organism’s metabolic processes  Direct evidence for evolution  Penicillin-resistance by some bacteria  Pesticide-resistance by some insects

30 IV. Other Evidence A. Fossils  Provide a record of early life and evolutionary history  Incomplete  Found throughout the world

31 IV. Other Evidence B. Anatomy 1. Homologous structures  Structural features with a common evolutionary origin  Similar in structure, function or both  Does not always mean that two species are related

32 2. Analogous structures  Any part that is similar in function but different in structure  Not used to indicate evolutionary relationship Birds and butterflies use wings to fly Butterfly wings made of chitin Bird wings made of bones IV. Other Evidence

33 3. Vestigial structures  Body structure in a present-day organisms that no longer serves its original purpose  Probably useful to ancestor  Ex. Appendix in humans, pelvis and femur in whales IV. Other Evidence

34 C. Embryology  Embryo – earliest stage of growth and development of plants and animals  Similarities in stages of embryonic development leading to distinct organism  Ex. Frogs and humans


36 IV. Other Evidence D. Biochemistry  Use of DNA, RNA, ATP, and comparisons  Amino acid sequence of cytochrome c differ among different species  More reliable  More similarities – closely related  Indicates levels of relationships



39 Mechanisms of Evolution

40  Only populations evolve and not individual organisms  Populations genes and frequencies change over time  Gene pool  The sum of all genes in a population  Tells us that evolution occurs I. Population Genetics

41  Allelic Frequency  The percentage of a particular allele in the gene pool

42  Genetic Equilibrium  A population in which the frequency of alleles remains the same over generations  Genetic equilibrium = no evolution  No equilibrium = evolution occurs I. Population Genetics

43  Gene Flow  Transport of genes by migrating individuals  Immigration – individuals enter pop. genes added to pool  Emigration – individuals leave pop. genes are lost from pool I. Population Genetics

44  Mutation  Results in useful variation  Genetic drift  Alteration of allelic frequencies by chance events  Affect small populations  Ex. Amish population II. Changes in Equilibrium

45 III. Types of natural selection

46  A. Stabilizing selection  Favors average individuals in a population Ex. Plants - too short, not be able to compete for sunlight - too tall, susceptible to wind damage - select for medium height will increase

47 Ex. Woodpecker - selection for long beaks  B. Directional selection  Favors one of the extreme variations of a trait

48 Ex. Limpets - light and dark colored limpets are favored  C. Disruptive selection  Favors either extreme of a trait’s variation

49 IV. The Evolution of Species

50 A group of organisms that have the ability to interbreed and produce fertile offspring Species Animal species Plant species

51  A. Speciation  Evolution of a new species  Occurs when members of similar populations no longer interbreed to produce fertile offspring within their natural environment IV. Evolution of Species

52  B. Geographic Isolation  Physical barrier divides a population  Droughts in forests, lava flows, sea level changes IV. Evolution of Species

53  C. Reproductive Isolation  Interbreeding organisms can no longer mate and produce fertile offspring  Ex. Tree frogs that mate in the summer cannot mate with those that mate in the fall IV. Evolution of Species

54  D. Change In Chromosome #  Polyploids  Species with a multiple of the normal set of chromosomes  Results from mistakes in mitosis or meiosis IV. Evolution of Species

55 V. Rates of Speciation

56 A. Gradualism  Species originate through a gradual change of adaptations V. Rates of Speciation

57 B. Punctuated Equilibrium  Speciation occurs relatively quickly, rapid bursts  Niles Eldredge, Stephen J. Gould V. Rates of Speciation

58 GradualismPunctuated Equilibrium Gradualism vs Punctuated Equilibrium

59 VI. Patterns of Evolution

60  Adaptive Radiation  When an ancestral species evolves into array of species to fit a number of diverse habitats. VI. Patterns of Evolution

61 Hawaiian honeycreepers

62  Divergent Evolution  Similar species become more and more distinct  Adaptation to different environmental conditions VI. Patterns of Evolution

63  Convergent Evolution  Distantly related organisms evolve similar traits  Unrelated species occupy similar environments in different parts of the world VI. Patterns of Evolution

64  Coevolution:  evolution of two or more interdependent species, each adapting to changes in the other  Predator/prey  Insects/flowers they pollinate VI. Patterns of Evolution


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