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Needham • It was known at the time that heat was lethal to living organisms. • Needham theorized that if he took chicken broth and heated it, all living things in it would die. • After heating some broth, he let a flask cool and sit at a constant temperature. • Result: Lots of microorganisms grew in flask Experiment • Took Needham’s testing further and sealed some of the jars so no air could enter • Boiled meat broth in two flasks • Open flask vs. sealed flask • Result: After three days, the broth in the open flask was cloudy = microorganism growth Pasteur’s Experiment • He repeated Spallanzani’s experiment, using a curved neck flask • Left it open for one year • Result: broth remained clear • Broke the neck & left it for one day - it was cloudy • Conclusion to all 3 experiments: spontaneous generation disproved • The New hypothesis: biogenesis: all living things come from other living things. Scientists Hypothesis Redi Maggots developed from eggs of flies Draw the Experiment Results Conclusion The uncovered jar had maggots & the covered one didn’t Spontaneous generation does not occur Needham Microorganisms were produced spontaneously Spontaneous Microorganisms generation occurs in microorganisms grew Spallazani Microorganisms are produced by other microorgansisms Spontaneous No microorganisms generation does not occur. grew Pasteur Microorganisms are produced by other microorgansisms No microorganisms Spontaneous generation does grew not occur. Evolution Review DESCENT WITH MODIFICATION (GENETIC CHANGE OVER TIME) Evolution http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter20/animation__mechanisms_of_evolution.html Cyanobacteria is a phylum of bacteria that obtain their energy through photosynthesis. The name "cyanobacteria" comes from the color of the bacteria (Greek: = blue). Although often called bluegreen algae, that name is a misnomer as cyanobacteria are prokaryotic and algae are eukaryotic. By producing oxygen as a gas as a by-product of photosynthesis, cyanobacteria are thought to have converted the early reducing atmosphere into an oxidizing one, which dramatically changed the composition of life forms on Earth by stimulating biodiversity and leading to the near-extinction of oxygen-intolerant organisms. According to endosymbiotic theory, the chloroplasts found in plants and eukaryotic algae evolved from cyanobacterial ancestors via endosymbiosis. Archaebacteria Sub-kingdom of the kingdom Prokaryote, which, on the basis of both RNA and DNA composition and biochemistry, differs significantly from other bacteria. They are thought to resemble ancient bacteria that first arose in extreme environments such as sulphur-rich, deep-sea vents.0. TYPES OF ADAPTATIONS • Structural • Behavioral • Physiological Let’s look at each type as we consider 2 species: the tundra & icecap-dwelling arctic fox & the desert dwelling fennec fox. arctic fox (Alopex lagopus) fennec fox (Vulpes zerda) Structural Adaptation: The form that the organism takes. EX: Big ears and small ears of foxes. Heat escapes easily from the blood that passes through the vessels in the fennec fox’s ears. Cool blood from the ears then circulates through the body & keeps the fennec fox from overheating. Structural Adaptations in Plants Behavioral Adaptation: These are innate (inherited) actions that individuals of the species perform. • Arctic fox: – Can be active any time of the day; ready to find food whenever available. • Fennec fox: – Is nocturnal; sleeps during the day & hunts at night Physiological Adaptation: Related to the biochemical processes at work within an organism’s body. • Compare the processing of food & water: – Arctic fox: food is scarce in winter; effective at storing food energy as fat. – Fennec fox: little free water available; adapted to get all moisture it needs from fruit, roots, & leaves. A whole lot happens inside our bodies and inside other organisms. Sometimes it is hard to see the physiological adaptations that an organism has. Organisms that make venom or poison are good examples of physiological adaptations. Or animals and plants in the desert that have special tissues to hold or absorb water are also good examples. The Giant African Millipede is toxic. It makes a poison that it releases through its skin, it keeps it from being a tasty treat for predators Snakes make venom to protect themselves and capture prey. It is a great adaptation Plants are able to bend toward the light, a process called phototropism. This is an excellent example of a physiological adaptation because it occurs inside the plant as a result of chemical reaction The Rate of Evolution Different kinds of organisms evolve at different rates Bacteria evolve much faster than complex cells The rate of evolution also differs within the same group of species In punctuated equilibrium, evolution occurs in spurts In gradualism, evolution occurs in a gradual, uniform way Punctuated equilibrium Gradualism PATTERNS OF EVOLUTION Coevolution: Change of two or more species in close association with each other. EXAMPLE: Bumblebees and the flowers they pollinate have co-evolved so that both have become dependent on each other for survival. Convergent Evolution: organisms that are very similar but are not closely related. This happens because of a change within the environment. Analogous structures are the result of convergent evolution. DIVERGENT EVOLUTION:Two or more related species that become more dissimilar due to different environments. •This usually produces another species EXAMPLE: GALAPAGOS FINCHES EVOLUTIONARY FORCES Five evolutionary forces can significantly alter the allele frequencies of a population 1. 2. 3. 4. 5. Mutation Migration Genetic drift Nonrandom mating Selection Mutation The ultimate source of new variation Errors in DNA replication and change in DNA due to extraneous factors Mutation rates are too low to significantly alter allele frequencies on their own Migration Movement of individuals from one population to another Immigration: movement into a population Emigration: movement out of a population A very potent agent of change Genetic Drift Random loss of alleles More likely to occur in smaller population Founder effect Small group of individuals establishes a population in a new location Bottleneck effect A sudden decrease in population size due to natural forces Mating that occurs more or less frequently than expected by chance Inbreeding Mating with relatives or self Increases homozygosity Outbreeding Mating with non-relatives Increases heterozygosity Nonrandom Mating Selection Some individuals leave behind more offspring than others Artificial selection Breeder selects for desired characteristics Natural selection Environment selects for adapted characteristics CLASSIFICATION • HISTORY OF TAXONOMY –Taxonomy the branch of biology that groups and names organisms based on their different characteristics • Organisms are named using Latin,and in a way that no two have the same name • ex) Canis lupis Common names make poor labels Zea saccharata Corn Zea mays indurata Ursus arctos horribilis Bears Phascolarctos cinereus Robins ARISTOTLE – GREEK PHILOSOPHER •1ST TO CLASSIFY ORGANISMS MORE THAN 2,000 YEARS AGO. •HE CLASSIFIED ALL LIVING THINGS AS EITHER PLANT OR ANIMAL •HE GROUPED PLANTS BASED ON THEIR STEMS •HE GROUPED THE ANIMALS BASED ON WHERE THEY LIVED OR DWELL. THE ANIMALS WERE DIVIDED INTO 3 CATEGORIES: ANIMALS LAND AIR WATER • The classification system of the Middle Ages was known as the polynomial system – Polynomials were a string of Latin words or phrases consisting of up to 12 or more words – This system was difficult and confusing – Even worse names were often changed often and without notice •In the 1750s, the Swedish biologist Carolus Linnaeus developed the binomial system – Binomials are twopart names •They have become our standard way of designating species Binomial nomenclature: two-word naming system (scientific name) for different species Scientists all over the world can communicate about an organism using its scientific name, regardless of country, language, etc. Written in Latin because Latin is no longer used and therefore does not change Each scientific name has two words that are italicized or underlined oFirst word: genus name (capitalized) oSecond word: species name (not capitalized) Homo sapiens Genus Species 36 Linnaean System • Taxonomist use a classification system to classify organisms • Carolus Linnaeus (1707-1778) • Classified organisms based on their morphology (form & structure) • Binomial nomenclature system: two-part naming • Linnaeus is the “father of classification” • The system of classification is used by taxonomists. Binomial Nomenclature • It gives every species a two-part scientific name. For example, a ladybug found in the United States goes by the fancy name of Harmonia axyridis. • The first part of a scientific name, like Harmonia, is called the genus. A genus is typically the name for a small group of closely related organisms. The second part of a scientific name, axyridis in this example, is the specific epithet. It is used to identify a particular species as separate from others belonging to the same genus. Together, the genus plus the specific epithet is the full scientific name for an organism. 10 38 • Binomial Nomenclature Rules • Because scientific names are unique species identifiers, they ensure that there is never any confusion as to which organism a scientist may be referring. Additionally, there are some important rules that must be followed to keep all binomial names standardized: 1. The entire two-part name must be written in italics (or underlined when handwritten). 2. The genus name is always written first. 3. The genus name must be capitalized. 4. The specific epithet is never capitalized. 39 •EX: lion – -PANTHERA LEO –Would be written: –Panthera leo –If writing by hand: –Panthera leo HOW MANY SPECIES ARE THERE? •Since the time of Linnaeus, about 1.5 million species have been named •However, scientists estimate that at least 10 million species exist –At least two-thirds of these occur in the tropics PHYLOGENY • Taxonomy also enables us to glimpse at the evolutionary history of life on earth • The evolutionary history of an organism and its relationship to other species is called phylogeny • The reconstruction and study of phylogenetic trees is called systematics – Phylogenetic tree= a family tree that shows the evolutionary relationships thought to exist among groups of organisms. Phylogenetic trees are generally derived from several lines of evidence such as: morphological, embryological, & macromolecular similarities A relatively new system of phylogenetic classification is called cladistics. As groups of organisms diverge and evolve from a common ancestor, they keep some of the same traits (derived traits) oCladogram: branching diagram that shows the derived traits of a group of organisms (like a pedigree that shows evolution) oThe closer 2 organisms are in a cladogram, the more probable that they are closely related by evolution o EX: if the group being considered is birds, one example of a derived character is feathers. Most animals do not have feathers; birds are the only animals that do, therefore it is safe to assume that feathers evolved within the bird group. Shared derived characters, particularly a group of several shared derived characters, are strong evidence of common ancestry between organisms that share them. When we do studies in comparative anatomy, and find that different numbers of shared derived characters exist between different groups, we can draw a diagram of branching lines which connect those groups, showing their different degrees of relationship. Diagrams showing the relationships of various organisms and their derived traits look like a slanted football field and are called cladograms. http://www.youtube.com/watch?v=46L_2RI1k3k http://ccl.northwestern.edu/simevolution/obonu/cladograms/Open-This-File.swf Cladogram practice handout Father of Classification Carl Linnaeus Binomial Nomenclature • Universal naming system still used today • Two-part: Genus and Epithet (description of species) • Genus IS capitalized; epithet is NOT • Both names are italicized or underlined • Ex. Felix domesticus (genus, species) • -or• Ex. Homo sapiens Higher Categories • Scientists use a hierarchical system to classify organisms (high low) • Higher categories = more general • Lower categories = more specific • 7 levels of classification • 8th = domain TAXONOMY CATEGORIES Taxonomists use a hierarchical system to classify organisms comprised of 7 different levels of organization •Kingdom As you go down the category gets more specific. •Phylum •Class •Order •Family •Genus •Species Linnaeus was responsible for this system! •The designation of kingdoms has changed over the years –Originally there were only two kingdoms •As more information about organisms was obtained, the number of kingdoms increased. •A taxonomic level higher than kingdom has been recognized- Domain. 53 Linnaean System of Classification Domain Kingdom Phylum Class Order Family Genus Species Current Levels of Organization https://www.brainpop.com/science/diversityoflife/classification/ D, K, P, C, O, F, G, S • • • • • • • • The Current Categories Do Keep Penguins Cold On Frozen Ground Sometime s “Did King Philip Come Over For Garlic Spaghetti” “Do Kings Play Chess On Fine Grained Sand” Now create your Some other sentences: own… the crazier it is •Do Kids Prefer Cheese Over Fried Green Spinach. the better you will •Do Koalas Prefer Chocolate Or Fruit, Generally Speaking remember! •Do Keep Precious Creatures Organized For Grumpy Scientists All 8 names for US!! (humans) The 3 DOMAINS DOMAIN ARCHAEA •Consists of only one kingdomArchaebacteria –Archaebacteria inhabit some of the most extreme environments on earth –They share certain key characteristics •Cell walls lacking peptidoglycan •Unusual lipids and unique rRNA sequences ARCHA EA •Live in harsh environments •Example: sewage treatments plants & thermal vents, etc. •May represent the 1st cells to have evolved DOMAIN BACTERIA • Consists of only one kingdom- Eubacteria –Bacteria are the most abundant organisms on Earth •There are more bacteria living in your mouth right They play critical roles now than there are mammals on Earth throughout the biosphere Most taxonomists recognize 1215 major groups –Bacteria are as different from archaebacteria as they are from eukaryotes BACTERIA • Some cause human diseases • Bacteria are present in all habitats on earth. •Example: in the intestines of animals EUKARYA • Divided into kingdoms… Appeared about 1.5 billion years ago Consists of four kingdoms 1. Animalia (animals) 2. Plantae (Plants) 3. Fungi (Mushrooms, yeast) 4. Protista (algae) 63 Six-Kingdom System • Carl Woese • A kingdom is the largest and most broad level of classification Animalia ▪ Plantae ▪ Fungi ▪ Protista ▪ Archaeabacteria ▪ Eubacteria ▪ Descriptions of Kingdoms • Animalia: Eukaryotic,multicellular, heterotrophic. • EX: wolves • Plantae: Eukaryotic, multicellular and autotrophic. • EX: Rose • Fungi: Eukaryotic, uni/multicellular, heterotrophic • EX: mushrooms, molds, yeasts Descriptions CONT…. • Protista: Eukaryotic, uni/multi, both auto and heterotrophic, usually found in a water environment • EX: algae, amoeba • Archaeabacteria: Prokaryotic, unicellular, auto/heterotrophic and lives in harsh environments. • EX: methanogens, thermophiles • Eubacteria: same as archaebacteria except living conditions are favorable bacteria • EX: food poisoning, tooth decay Building Family Trees • Phylogeny - Evolutionary history of an organism and its relationship to other species • Cladogram- Evolutionary lineage based on PHENOTYPES • Phylogenetic trees Evolutionary lineage based on GENOTYPES DICHOTOMOUS KEYS •A written aide in the classification of organisms •Uses pairs of contrasting, descriptive statements to lead to the identification of an organism. Dichotomous Key Sample Key: 1. Has light blue colored body… go to 2 Has dark blue colored body… go to 4 2. Has 4 legs… go to 3 Has 8 legs… Deerus octagis 3. Has a tail… Deerus pestis C Does not have a tail… Deerus B magnus 4. Has a pointy hump… Deerus humpis A Does not have a pointy hump… go to F5 5. Has ears… Deerus darkus Does not have ears… Deerus deafus D E