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142 Cards in this Set
- Front
- Back
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Robert Chambers
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• Robert Chambers was the last great champion of the 19th Century fascination with progressivism
• Chambers was a wealthy publisher and an amateur naturalist • Thought evolution was continuous and gradual (= modern) • Still clung to the Argument from Design |
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System of Linear development
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• Chambers’ System of Linear Development was a very Lamarckian theory
• Chambers’ Vestiges of the Natural History of Creation (1844) caused a scandal • Claimed that man was descended from the lower animals ( = modern) |
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Charles Darwin
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• Chambers’ System of Linear Development was a very Lamarckian theory
• Chambers’ Vestiges of the Natural History of Creation (1844) caused a scandal • Claimed that man was descended from the lower animals ( = modern) • Darwinian revolution removed man from the center of creation, as the Copernican revolution had removed the Earth from the center of the universe • Man was just another organism, evolved through gradual change from lower animals • Darwin eliminated the Argument from Design as a scientific theory • Darwin eliminated the Chain of Being - man was just another branch on the tree of life • He was a very unlikely and very unwilling revolutionary • Born in Shrewsbury, England, fifth child of a wealthy family • Maternal grandfather was Josiah Wedgewood (Wedgewood pottery) • Paternal grandfather was Erasmus Darwin, who had written a book on evolution (Zoonomia) from a Lamarckian viewpoint • Family was well educated, professional • Family loved outdoor sports • Charles was an avid collector of beetles • Each island had one or more species of finches • Each species of finch was adapted to the environment of each individual island • Ancestral finch must have reached the islands from South America, gradually spread out over the archipelago • Different local conditions caused them to diverge into a closely related group of species • Unfortunately, almost none of it is true… • Darwin didn’t even know that the birds he was observing were finches, much less related species • It was tortoises, not finches, that started him thinking about evolution • Galápagos tortoises are large, long-lived • Natives could tell by looking at them which island they came from • It was mockingbirds, not finches, that helped Darwin make his critical insight into the nature of evolution • He recognized the mockingbirds, and observed that they were very similar to species he had seen on the mainland • Their ancestors must have arrived from the mainland, and evolved in geographical isolation, in response to local conditions • It was not until 1838, two years after returning home, that Darwin finally realized how this must have occurred • He knew that animals could pass particular traits on to their descendants • Farmers could even breed animals for specific characteristics • They did so by selecting individuals with particular desirable traits to breed together |
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Robert FitzRoy
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• The Captain of the Beagle was a 26 year-old gentleman named Robert Fitzroy
• Fitzroy had advertised for a gentleman’s companion, preferably a naturalist • Fitzroy was moody, contentious, intensely devout |
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H.M.S Beagle
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• The H.M.S. Beagle was about to set sail for South America, and the captain was advertising for a gentleman naturalist
• Beagle set sail for South America in December 1831 • Beagle was to map the southern coast of South America, explore the interior, visit tropical islands and native tribes along the way • Voyage would expose Darwin to an incredible wealth of exotic plants and animals • Would visit jungles, deserts, coral islands, make several expeditions inland • Beagle finally reached the Galápagos Islands in September of 1835 |
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Origin of Species
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• Finally published the Origin of Species in 1859, revealing his theory of Evolution by Natural Selection
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Alfred Russell Wallace
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• Finally published the Origin of Species in 1859, revealing his theory of Evolution by Natural Selection
• Heard through a colleague that the naturalist Alfred Russel Wallace was about to publish the same theory, even hitting on the same name! |
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Thomas Malthus
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• In 1838, Darwin read An Essay on the Principle of Population, published in 1798 by Thomas Malthus
• Thomas Robert Malthus - born in 1766 near Guilford England (Albury Parish, Surrey) • Second son of seven children • Godfathers were Jean Jacques Rousseau, David Hume - dad was a bit radical… • Borne with a speech impediment - hare lip and cleft palate • Lived a quiet life, with his parents, who called him Bob… • Bob may have gotten his inspiration from his father, arguing over social philosophy • Utopian schemes were all the rage • Utopian philosophers felt that nature had much to teach us • Social evolution followed natural evolution, nations could evolve into utopias • Dad was a “free thinker”, believed that the utopians were correct • Malthus disagreed… • Home schooled, later taught by radical social philosopher Gilbert Wakefield, at a school called the Dissenting Academy • Very liberal education… • Teacher jailed for seditious libel in 1799 • Malthus studied theology at Cambridge 1776 to 1782 , was ordained into the Church of England in 1788 • Was a good student, popular with his peers, "often a source of infinite delight and pleasantry to his companions…wont to set the table in a roar." • Eventually moved a few miles down the road from his parents, as curate of Okewood Chapel • 1804, age of 39, married his first cousin Harriet (age 28…hmmm), had 3 children (moderate for the times) • Access to parish registers of births and deaths, gave him statistical data on the growth of the local population, which was booming • Malthus published his Essay on the Principle of Population in 1798 • It was a runaway bestseller • He was on Letterman twice… • Everyone read the Essay or talked about it • Malthus wrote to counteract arguments that social progress could be achieved through a better understanding of nature • Malthus agreed that nature had a lot to say • But what nature really had to tell us was not very pleasant • Nature demonstrates that progress is only possible with enormous suffering and sacrifice of life • Wars, famines, plagues…these were nature’s way of balancing the books on the excess human population • Malthus thought that the “passion between the sexes” was too instinctual to be reasonably controlled or restrained • Besides, sex was supposed to feel good! • Sexual passion was part of the divine plan behind nature, “be fruitful and multiply” • Malthus did not object to the exercise of passion, but to the lack of sexual moderation among the lower classes • We were just too damned fruitful… • Was a 32 year old bachelor, still living with his parents when he wrote his famous essay • Basic argument was entirely mathematical • Population would increase geometrically, but resources could only increase arithmetically • Over time, this would lead to a growing gap between too many people and too few resources |
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Struggle for existance
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what Malthus called “the struggle for existence”
• Ideas were a major influence on Darwin, who reasoned that what was true of humanity must also apply to other animals as well - a struggle for existence • In any struggle, there would be winners and losers • The winners must be those individuals better equipped to survive, what Herbert Spencer was to later call survival of the fittest |
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Survival of the Fittest
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The winners must be those individuals better equipped to survive, what Herbert Spencer was to later call survival of the fittest
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Natural Selection
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• Darwin realized that evolution must be tied to variation
• Species were really just local groups of individuals, all of whom varied from one another in certain ways • This focus on species as groups of populations was very revolutionary • Just as farmers selected the best varieties to breed, nature must somehow select those individuals best fit to survive • In every natural population, some varieties must be better equipped to prevail in the struggle for existence • Those well adapted individuals would have more offspring than others, passing on their variation to the next generation • Darwin realized that evolution was a selective process, what he called natural selection |
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Thomas Huxley
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• Huxley became known as “Darwin’s Bulldog”
• Huxley had written a flattering review of the Origin of Species, started a lifelong friendship • Huxley was a very strange young man • Huxley sailed aboard H.M.S. Rattlesnake • One of a new breed of young radicals, who saw evolution as a two-edged sword • Could challenge stuffy old profs and stuffy old clerics all at the same time • Huxley coined the word agnosticism • Huxley started the journal Nature, so Darwin’s followers would have a place to publish their papers • Huxley founded the X-Club, secret society of Darwin’s supporters |
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Darwin's bulldog
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Huxley became known as “Darwin’s Bulldog
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Gregor Mendel
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• Gregor Mendel, in 1866, experimented with garden peas, discovered the mechanism of heredity
• Darwin never heard about Mendel’s results • Mendel published his data in an obscure journal, article was ignored, few read it, none appreciated or understood it • Mendel was too humble to draw attention to his results, published in Czechoslovakian in a local natural history journal • Focused on discontinuous variation, all or none, unlike Darwin (continuous variation) • Mendel showed that: > The physical units of heredity came in pairs, one unit from each parent > Heredity was particulate, not blending of fluids (contrast with Darwin) > Variation was not continuous, but discontinuous • Classic example is the cross between two pure strains of garden peas • Tall peas had two “tall” units (TT) • Short peas had two “short” units (tt) • First cross between TT and tt would yield plants that were all tall • However, when two of these tall plants were crossed with one another, the next generation would be a mixture of tall and short - how could this happen? • We now refer to these units as genes, so there is a pea gene for tall (T) plants and one for short (t) plants • If two similar genes come together we call the plant homozygous (TT or tt) • If two different genes come together we call the plant heterozygous (Tt) • Mendel discovered that some genes were dominant over others, and would mask the effects of the second gene (T - tall) • Other genes were recessive (t - short) • Alleles are different versions of the same genes (original “wild type”, mutated form) • Followers of Mendel became opposed to followers of Darwin (Mendelism vs. Darwinism) • Mendelism focused on the mechanics of heredity and mutations (changes in genetic information) • Biology was split into two parallel paths |
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Theodosius Dobzhanksky
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Theodosius Dobzhansky’s Genetics and the Origin of Species (1937)
• Dobzhansky translated the complex models of population genetics into terms the field biologists could understand • Made geneticists realize the importance of how genes moved through natural populations (population genetics) • Speciation (formation of new species) required geographic isolation • Small isolated populations often developed distinctive genetic differences (plumage, courtship behavior etc…) • These differences could eventually become isolating mechanisms • These mechanisms would keep populations from interbreeding if/when geographic barriers were removed, and they were reunited with one another (secondary contact) - they would be a new species • Consider the first few finches that reached the Galápagos Islands • Isolated from the parent population • Spread from island to island, forming several isolated island populations • Each island population had slightly different gene pool (total variation of population) • Shaped by different conditions on each island (ex. food supply) • Change in frequency of certain genes over time (ex. larger or smaller beaks) • Differences would accumulate to the point where the new population could no longer interbreed with the parent population • They would have become a new species • Biological species concept - species are populations of similar organisms that can interbreed with one another, but are reproductively isolated from other such populations by one or more isolating mechanisms |
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Geographical Isolation
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• Evolution depended on variation, but mutation kept introducing new variation into the system
• Geographic isolation was important, but evolution happened faster in small populations than in large populations |
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Blended heredity
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• Darwin believed in blended inheritance - gradual and continuous process
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gemmules
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• Tiny particles called gemmules carried the information of heredity
• Gemmules floated in different parts of the body, knew how to make that body part • Gemmules moved to the reproductive organs during sex = blended inheritance |
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allele
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• Alleles are different versions of the same genes (original “wild type”, mutated form)
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dominant allele
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• Mendel discovered that some genes were dominant over others, and would mask the effects of the second gene
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recessive allele
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• Other genes were recessive
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heterozygous
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• If two different genes come together we call the plant heterozygous
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homozygous
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If two similar genes come together we call the plant homozygous
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mutation
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mutations (changes in genetic information)
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modern synthesis
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• Fusion of abstract models of genes moving through populations, with the population perspective of field biologists, formed the modern synthesis
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variation
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• Evolution depended on variation, but mutation kept introducing new variation into the system
> Variation not “noise” but information • Mendel showed that > Variation was not continuous, but discontinuous |
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population
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> Switched the view of species as fixed and distinct types to viewing species as groups of local populations that varied from one another
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evolution
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• Individuals with adaptive variations would survive better, reproduce more often
• More of their genes would be passed on to the next generation - change in gene frequency over time (differential reproduction) = evolution !! |
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species
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• What Darwin accomplished:
> Switched the view of species as fixed and distinct types to viewing species as groups of local populations that varied from one another |
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speciation
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• Speciation (formation of new species) required geographic isolation
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Darwin's theory of evolution by natural selection
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• Finally published the Origin of Species in 1859, revealing his theory of Evolution by Natural Selection
• Darwin’s Theory of Evolution: > Growth with reproduction, inheritance > Variation in populations > Struggle for existence • Darwin’s Theory of Evolution: > Natural selection of certain varieties > Change in proportion of those varieties in the next generation > Extinction of poorly adapted forms |
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Biological species concept
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• Biological species concept - species are populations of similar organisms that can interbreed with one another, but are reproductively isolated from other such populations by one or more isolating mechanisms
• This was not quite how Darwin saw it • Evolution depended on variation, but mutation kept introducing new variation into the system • Geographic isolation was important, but evolution happened faster in small populations than in large populations |
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Homologous chromosome
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• Higher organisms have two copies of each chromosome, one from each parent = homologous chromosomes
• Homologous chromosomes contain the same genes at the same loci • But the same loci may have different alleles on each homologous chromosome |
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chromatid
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• Each X-shaped chromosome is actually two chromatids, fastened at the center
• Each chromatid is a complete strand of DNA, a sequence of genes • A gene is simply a segment of a chromatid that codes for the creation of a particular protein |
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amino acid
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• Each protein is made up of a linear series of amino acids
• Genes code for the sequence of amino acids used to build each protein |
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protein
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• Each gene codes for a single protein – traditional view
“alternative splicing”, one gene can contribute subunits to several different proteins |
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enzyme
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> Enzymes - most proteins are enzymes
• Enzymes are catalysts - they affect chemical reactions, but are not changed by reactions • Catalysts have charged areas that attract two molecules, hold them in place so they react • Catalysts then separate - each enzyme molecule can catalyse several reactions • Enzymes control the direction of reactions -many chemical reactions are reversible • Enzymes cause reactions to occur within a narrow range of temperature and pressure • Enzymes greatly increase reaction rates • Enzyme amount controls amount of product • Small changes in enzyme structure can strongly affect their ability as catalysts |
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nucleotide
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organic compounds
• Nucleotides form complementary base pairs > Adenine (A) pairs with Thymine (T) > Guanine (G) pairs with Cytosine (C) > Uracil (U) substitutes for Thymine (T) in RNA, so A/U and G/C for RNA |
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DNA
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• DNA (deoxyribonucleic acid) - two strands in a coiled helix, each made up of a series of organic compounds called nucleotides
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RNA
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• RNA (ribonucleic acid) is a single strand of nucleotides
• Nucleotides are attached to a backbone of sugar and phosphate molecules |
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Codon
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• Each of the 20 amino acids is coded for by a sequence of three nucleotides (codon)
• There are 4*4*4 = 64 possible codons that could be represented in DNA or RNA • Many codons code for the same amino acid, so the system is redundant |
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Protein synthesis
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• Protein synthesis starts with the creation of a mirror image of each strand of DNA
• This mirror image is a single strand of messenger RNA (mRNA) • Messenger RNA moves from the nucleus out to the cytoplasm • Ribosomes attach to mRNA • Ribosomes mainly consist of special RNA called ribosomal RNA (rRNA) • Ribosomes move along the strand of mRNA, read each sequence of three (codon) • Transfer RNA (tRNA) has two binding sites, one is an anticodon, the other attaches to the appropriate amino acid • Transfer RNA carries the amino acids to the ribosomes to be attached to the growing chain • Once the amino acids are assembled in a row, their positive and negative areas attract or repel each other • Amino acid chain spontaneously folds up into a particular shape (electrically stable) • The final 3-dimensional shape gives each protein its special properties • Higher level structure is built into the sequence of amino acids • Doesn’t require extra energy to curl into shape - nifty! |
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mutation
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• Mutations are random alterations in genetic information
• Minute changes caused by mutations can have a profound effect on the organism • Mutations relatively rare, usually have a small effect - positive, negative, neutral • Mutations can occur when DNA replicates • Point mutation - change at a single point along a strand of DNA > New triplet may code for a different amino acid > New triplet codes for a stop codon > May code for the same amino acid (redundant) > Frameshift mutation - new base inserted into the sequence, shifts the frame for reading all subsequent groups of three bases • Mutations can also occur in chromosomes: > Change in the amount of genetic information (polyploidy, ex. 2N to 4N) > Rearrangement of genetic information • Deletion • Duplication • Inversion • Translocation |
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genetic recombination
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• Meiosis shuffles existing variations into infinite new combinations (genetic recombination)
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sexual recombination
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• Sexual reproduction is nearly universal among higher organism
• Creates an incredible number of new beings from a relatively small number of alleles (sexual recombination) |
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Mitosis
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regular cell division (mitosis)
• In mitosis, the object is to make two identical diploid daughter cells > Chromatids replicate before division > Chromosomes line up at the center > Chromatids separate, go to daughter cells > Daughter cells are now identical • Second cell division - mitosis > Chromosomes line up at the center > Chromatids separate to daughter cells > Each daughter cell divide into two haploid cells |
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Meiosis
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• Meiosis shuffles existing variations into infinite new combinations (genetic recombination)
• In meiosis, object is to turn one diploid cell into four haploid daughter cells (gametes) • In meiosis there are two complete cell divisions • Need to reduce the chromosome number - first division is a reduction division, turns diploid cell into two haploid cells • Second cell division - mitosis > Each of the four daughter cells now has a single chromatid from each unique chromosome, one complete copy of all the genetic information |
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Haploid
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• Organisms with one of each type of chromosome (1N) are called haploid
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Diploid
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• Organisms with two of each type of chromosome (2N) are called diploid
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reduction division
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• In meiosis there are two complete cell divisions
• Need to reduce the chromosome number - first division is a reduction division, turns diploid cell into two haploid cells • Reduction division > Homologous chromosomes line up at the center of the cell > For a brief time they are physically joined together (chiasmata) > One homologous chromosome goes to each daughter cell (random) |
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Independent assortment
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• The direction each chromosome takes during reduction division is random (independent assortment)
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Crossing over
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• During the reduction division, the homologous chromosomes are briefly joined together
• While they are joined, they can exchange genes or groups of genes (crossing over) |
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Genetic polymorphism
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• Genetic polymorphism (genes exist in “many forms” , i.e. multiple alleles) is common among higher organisms
• About 33% of human genes polymorphic • Fruit fly genes are 53% polymorphic • Genetic polymorphism is beneficial for the evolution of the species |
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Hardy-Weinberg equilibrium
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• G. Weinberg (German doctor) and G.H. Hardy (British mathematician), made an interesting discovery in 1908
• If large populations mate randomly, the proportion of two alleles will never change • In other words, they discovered that evolution is mathematically impossible • Hardy-Weinberg Equilibrium > For any two alleles (Aa), let p and q represent the frequency of those alleles (so p2 = AA, q2 =aa, 2pq = 2Aa) > If all three possible genotypes mate with one another, in the next generation the frequencies will be equal to p2 + 2pq +q2 = 1 [simple binomial equation, (p + q)2] • Let all genotypes mate again, the result will be exactly the same • Works with any number of alleles (p + q + r)2 = 1 • Gene frequencies will always be in equilibrium |
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Gene frequency
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> Evolution is change in gene frequency over time
> Gene frequencies never change over time > Therefore evolution cannot occur….. Makes the Hardy-Weinberg equilibrium impossible |
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Population genetics
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• Variation drives the evolution of individuals
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Gene flow
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> Gene flow occurs between local populations
> Populations consist of neighborhoods > Someone’s always moving in or out > Amount of gene flow depends on dispersal ability (birds vs. snails) |
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Immigration
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organism enters a population
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Emigration
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organism leaves a population
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Inbreeding
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• Evolution is most likely to occur in small inbred populations, where random accidents can have a significant effect
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Monogamy
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which a given individual has only one sexual partner throughout life
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Serial Monogomy
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series of long- or short-term, exclusive sexual relationships entered into consecutively over the lifespan.[1] In common usage partners need not be married, but there is never more than one partner at a time.
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Polygamy
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a person [has] more than one spouse
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Polygyny
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– polygyny (one male, many females)–
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Polyandry
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– polyandry (one female, many males)
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Founder effect
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the gene pool of an isolated population will be a random subset of the gene pool of the parent population
• Founder effect shows that chance events can affect gene frequencies in unexpected ways |
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Genetic drift
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• Founder effect is a special case of genetic drift - change in allele frequencies in small isolated populations due to random events
• Genetic drift has nothing to do with adaptation or natural selection - it is strictly a statistical phenomenon |
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isolating mechanism
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• Isolating mechanism - any factor that acts to reduce or block the flow of genes between two populations
> Geographic isolating mechanisms > Reproductive isolating mechanisms – Temporal — Mechanical – Behavioral — Ecological |
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geographic isolating mechanism
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• Speciation begins when small parts of a larger population are geographically isolated from the parent population
• Differences in local conditions favor different varieties in the isolated population, whose gene pool is a subset of the original population • Because they are geographically isolated, members of this small populations can only interbreed with one another • Mutations and recombinations within this isolated population can lead to entirely new varieties, and new combinations of existing traits • The population may experience genetic drift, a random fluctuation in the proportion of a particular allele in a small inbred population • Natural selection favors some combinations of alleles over other combinations • Over time, the effect of natural selection, genetic drift, mutation, and recombination can become isolating mechanisms |
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Reproductive isolating mechanism
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• When the isolated population is reunited with the parent population, they can no longer interbreed. They have become reproductively isolated, and can now be considered a new species
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Temporal isolating mechanism
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• Temporal isolating mechanism - population becomes isolated in time
> Many species have a fixed breeding season > Shift in timing of breeding could isolate them > Pinus radiata sheds pollen in February > Pinus attenuata sheds pollen in April |
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Behavioral isolating mechanism
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• Behavioral isolating mechanism - changes in behavior, especially courtship and mating behavior
> Animals often have complex stereotyped behavior patterns that are under genetic control > Even a small change in courtship behavior could have a big effect on reproduction |
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Mechanical isolating mechanism
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• Mechanical isolating mechanism - the parts no longer fit together
> Could be extreme difference in size > Could be change in shape of genitalia > Most important in plants - affects pollination (change in stigma, shape or color of petals…) |
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Ecological isolating mechanism
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• Ecological isolation - don’t meet, don’t mate
> Many species have ecological races - specialized to live in a particular habitat > Deer mouse Peromyscus has forest race and prairie race > Certain flowers have sun race and shade race > Fleas and other parasites are host-specific |
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Species
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• Only when populations become isolated will small changes in variation cause them to diverge into new species
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Directional selection
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• Directional Selection - average value of a trait is shifted in a particular direction (higher or lower)
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Stabilizing selection
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• Stabilizing Selection - acts to stabilize the population around some average value
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disruptive selection
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• Disruptive or Diversifying Selection - the environment selects for the two extremes, against the average, splitting the population in two or more types
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industrial melanism
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• Industrial melanism - replacement of a light morph by a dark morph in an industrialized area - nearly 200 species of Lepidoptera
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microevolution
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• Microevolution is evolution at or below the level of the species
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macroevolution
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• Macroevolution is evolution above the level of the species (orders, classes etc…)
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adaptation
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• Darwin’s finches differ mainly in the size and shape of the beak
• These differences are adaptations to the local food supply |
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homologous structures
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• The wings of a bird and the wings of a bat are homologous structures
• Homologous structures are structurally and developmentally similar, even though they may be put to very different uses • Homologous structures are derived from a common ancestor • The legs of a cat are homologous with the wings of the bird it chases • The flipper of the whale is homologous with the human arm • The jumping legs of a frog are homologous with the legs of the bird that eats it |
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analogous structures
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• Sometimes structures appear similar, and may even serve the same purpose, but they are fundamentally different from one another
• The wing of a bird and the wing of an insect are analogous structures • Analogous structures are superficially similar, but structurally and developmentally different • Fish and dolphins have a very similar shape • Fish are not directly related to dolphins • Why do they both have the same basic shape?? • Being streamlined is the most efficient way to move through water! • Analogous structures evolve because there are a limited number of solutions to evolutionary challenges > flight requires wings > swimming requires streamlining |
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divergent evolution
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• Homologous structures are evidence of divergent evolution, divergence from a common ancestor
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convergent evolution
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• Convergent evolution - two unrelated lineages converge on a common solution to an evolutionary problem
• Analogous structures are evidence of convergent evolution, convergence on a common type of adaptive shape or structure |
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punctuated equilibrium
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• New types of fossils often appear abruptly, and last through long periods of relative stability until they abruptly disappear
• S.J. Gould and Niles Eldredge call this pattern punctuated equilibrium • Species would be most likely to evolve in small, isolated populations • Because of the small size of these “founder” populations, extremely few of these early individuals would end up preserved as fossils • Over time, as the population grew large enough, a few individuals would be preserved as fossils • It would appear as though they had instantaneously emerged into the world • Once they began to spread, they might drive less competitive species into extinction • One species seems to abruptly disappear (old), replaced by a very similar species (new) • So the fossil record shows a pattern of long periods of relative equilibrium (slow or no change), interrupted by bursts of speciation • Theory has caused a lot of controversy, but it’s really a matter of tempo, not evolutionary mechanism • Gould and Eldredge show us how the fossil record reflects the pattern of speciation • There are many strong lines of circumstantial evidence that point to the same underlying pattern in nature, a pattern that Darwin perceived • The branching pattern of nature is a simple consequence of descent with modification from a common ancestor |
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six kingdoms
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• Six Kingdoms of Life – Bacteria, Archaea, Protista, Animalia, Plantae, Fungi
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phylogeny
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evolutionary history
• Phylogeny is the evolutionary history of organisms (their lineage) |
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Taxon
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• Taxon (taxa) - any rank in classification, a collection of related organisms
• Domain, Kingdom, the highest ranks • Genus, species, subspecies, race - the lowest ranks • Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species (D K P C O F G S) |
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Taxonomy
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• Taxonomy is the description, naming, and classification of living organisms
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Cladism
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• Our current scheme of classification is called cladistic analysis or cladism
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Cladogram
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• Each taxon is a clade, a branch on the tree of life (cladogram)
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Clade
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• Each taxon is a clade, a branch on the tree of life (cladogram)
• Clades are determined by traits they share, traits that are different from their ancestors |
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Synapomorphy
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• Clades are determined by traits they share, traits that are different from their ancestors
• We call these traits synapomorphies, shared derived characteristics |
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monophyletic
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• Monophyletic - taxon contains the common ancestor and all of its descendants
• Monophyletic - contains the common ancestor and all of its descendants |
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paraphyletic
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• Paraphyletic - contains common ancestor but only some descendants (most similar)
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polyphyletic
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• Polyphyletic - contains some descendant species but no common ancestor (may even come from different ancestors)
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autotroph
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• Autotroph = self-feeder, autotrophic organisms produce their own energy
> Sunlight (photosynthesis, use H2O) 6CO2 + 12H2O + light => C6H12O6 + 6H2O + 6O2 > Chemical reactions (chemosynthesis, ex. H2S) |
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Motile
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• Bacteria ---(can move about
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Bacillus
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> Bacillus - rod shaped
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Coccus
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> Coccus - sphere shaped
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Spirillum
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> Spirillum - spiral shaped
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Prokaryote cell
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• Bacteria and Archaea are prokaryotes
> Primitive cells, unicellular > Lack a cell nucleus (no nuclear membrane around chromosomes) > Lack cellular organelles bound by membranes (no chloroplasts, no mitochondria, etc…) |
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Eukaryote cell
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• All higher organisms (Eukarya) are eukaryotes
> Complex cells, multicellular (some are unicellular) > Nucleus (enclosed by a nuclear membrane) > Cellular organelles enclosed by membranes (mitochondria, chloroplasts etc…) • Eukaryotic cells are much more complex, took another 2 billion years to evolve • May have evolved from endosymbiosis - devoured cell that became part of it - mitochondria, chloroplasts |
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Domain
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• Three Domains of Life – Bacteria, Archaea, Eukarya
• What the heck are Domains and Kingdoms? • The highest levels in the hierarchical classification of organisms |
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Rank order
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Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
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chemosynthetic
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> Chemical reactions (chemosynthesis, ex. H2S)
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carnivorous
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eats meat
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herbivorous
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eats plants
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omnivorous
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eats plants and meat
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saprobe
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• Heterotrophs can be parasites or saprobes
• Saprobes get their energy from dead and decaying organic matter • Extracellular digestion - saprobes secrete enzymes to do the digestion outside the cell |
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nitrogen fixation
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• Importance of bacteria
> Nitrogen fixation - turn atmospheric nitrogen (N2) into a form that plants can use (NH3 - ammonium) |
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Domain Archaea
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Archaebacteria
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Domain Bacteria
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Eubacterai
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Domain Eukarya
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Everything Else (Eukaryote cells)
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Kingdom Archaea
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Methanogens, Halophilic bacteria, thermophilic archaeans
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Kingdom bacteria
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Cyanobacteria, Nostoc, Anabena, Oscillatoria
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Heterotroph
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• Some bacteria are heterotrophs
• Heterotrophs = fed by others, heterotrophic organisms eat other organisms to survive > Herbivorous > Carnivorous > Omnivorous |
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Photosynthetic
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> Sunlight (photosynthesis, use H2O)
6CO2 + 12H2O + light => C6H12O6 + 6H2O + 6O2 |
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Root nodules
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> Nitrogen fixation - turn atmospheric nitrogen (N2) into a form that plants can use (NH3 - ammonium)
> Forms nodules on roots of legumes like clover, soybeans, alfalfa |
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Heterocyst
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> Cyanobacteria have heterocysts - enlarged structure where nitrogen fixation takes place
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Stramatolites
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• Stromatolites - thick mats, go back 2.7 billion years, one of the first ecosystems on Earth
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Kingdom Protista
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Protozoa= heterotrphic protist
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Phylum Euglenozoa
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Euglena
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Phylum Dinoflagellata
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Dinoflagellates (Ceratium, Gonyaulax)
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Phylum Apicomplexa
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Plasmodium- malaria
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Phylum Ciliophora
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Paramecium, blepharisma
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Phylum Amoebozoa
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Amoeba
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Phylum Foraminifera
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Faraminifera
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Algae
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autotrophic protists
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Phylum Phaeophyta
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Brown algea (Fucus, sargassum, kelp)
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Phylum Bacillariophyta
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diatoms
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Phylum Rhodophyta
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Red algae (polysiphonia, nemalion)
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algea
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• Kingdom Protista - 65,000-200,000 species (est.), fr. Greek protos = first, ktistos = established - algae, protozoans
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Protozoa
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• Some are heterotrophs = protozoa
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Diffusion
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• Protists are so small they don’t need special organs to exchange gas or excrete wastes
• They rely on diffusion - passive movement of molecules from area of higher concentration to area of lower concentration • Diffusion results from the random movement of molecules • Diffusion is a two edged sword • Protists don’t need to invest in complex respiratory or excretory tissue • They have to stay tiny - diffusion only works if you’re very small • Most protists are single cells |
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Phagocytosis
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• Protists eat by phagocytosis
> Engulf food in cell membrane > Pinch off membrane to form a vacuole > Vacuoles store food, water, enzymes, wastes |
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Pseudopodia
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• Protozoa - heterotrophs
> Motile – Cilia – Ciliophora, Euglenozoa – Flagella - Dinoflagellata – Pseudopodia – Amoebozoa, Foraminifera |
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Carrageen
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> Carrageen, thickening agent also extracted from cell walls of red algae, used in making ice cream, lunch meats, cosmetics, and paint
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diatomaceous earth
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> Shells form deposits called diatomaceous earth, used in abrasives, talc, and chalks
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Red Tide
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> Algal blooms of dinoflagellates are the cause of red tide - 20 species produce potent toxins
> 1987 outbreak killed half the Western Atlantic population of bottlenose dolphin! |
