Evolution Test #1

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Evolution Test #1
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  1. What is Anthropology?
  2. 1.The study of humankind. 2.The study of all aspects of the human species, including our biology
  3. What are the subfields of Anthropology?
    • Cultural anthropology
    • Archaeology
    • Linguistic anthropology
    • Biological anthropology
  4. What is Biological (Physical) Anthropology?
    It is the study of human biology within evolutionary framework.

    • Two principal areas of interest:
    • 1. Biological variation
    • 2.How modern species (including our own) came to exist
  5. What is variation?
    • •Variation refers to differences between individuals within populations as well as between populations.
    • •Anthropologists are interested in variation in terms of both biology and culture.
    • Individuals in a population vary from one another
  6. What is Evolution?
    • •Evolution is change in living organisms over time.
    • •Both cultural and biological evolution interest anthropologists.
    • Evolution is a fact…living organisms have changed in the past and continue to change today. There are forms of life living today that did not exist in the past and vice versa.
  7. Some Subfields of Biological Anthropology
    • •Paleoanthropology - study of the human fossil record
    • Human genetics - study of the human genome
    • Primatology - study of nonhuman primates.
    • •Osteology - study of skeletons.
  8. The scientific method:
    a problem is identified, a hypothesis is stated, and the hypothesis is tested by collecting and analyzing data.
  9. Facts:
    verifiable truth
  10. Hypothesis:
    A testable explanation of observed facts
  11. Testability
    Scientific hypotheses must be testable and falsifiable
  12. Theory
    A set of hypotheses that explain a large body of concrete facts, have been tested repeatedly and that have not been rejected
  13. What is natural selection?
    • Natural Selection is a SCIENTIFIC THEORY that explains how organisms are biologically transformed.
    • Survival of some individuals over others because they have specific characteristics that better their odds of survival and reproduction.
  14. Inheritance
    parents pass on their traits to their offspring genetically
  15. Selection
    some variants survive and reproduce more than others
  16. Time
    successful variations accumulate over many generations
  17. Science and Religion
    • •Many people feel that evolution represents a threat to their religious beliefs and is incompatible with spirituality.
    • •Creationism, Intelligent Design, and the existence of God are not scientific hypotheses.
    • •Science cannot rule out the existence of a creator.
  18. Misconceptions About Evolution
    • Natural selection is “just” a theory….. but you don’t get better than that in science.
    • There is a lot of contention about evolution…but not among scientists.
    • Evolution does not imply progression and has no end goal.
    • Evolution is a scientific concept and does not have to be incompatible with religion or belief in God.
  19. Biological evolution
    A change in the genetic structure of a population. Also refers to the appearance of a new species.
  20. Natural selection
    Mechanism for change favoring the survival and reproduction of some organisms over others because of their biological characteristics
  21. Fixity of Species
    The notion that species, once created, can never change; an idea diametrically opposed to theories of biological evolution.
  22. The Scientific Revolution
    • Discovery of the new world challenged fundamental views about the planet.
    • Exposure to new plants and animals increased awareness of biological diversity.
  23. Aristotle’s Worldview
    • This beautifully illustrated seventeenth-century map shows the earth at the center of the solar system.
    • Around it are 7 concentric circles depicting the orbits of the moon, sun, and the 5 planets that were known at the time.
  24. Nicolaus Copernicus (1514)‏
    Heliocentric theory: Earth and planets revolve around the sun
  25. Galileo Galilei (1564-1642)‏
    • Used mathematics to confirm Copernicus’ ideas
    • Universe is dynamic, not static
    • Earth not a focal point
  26. Keppler, Descartes and Newton (1600s)
    established the laws of physics, motion and gravity.
  27. John Baptiste Lamarck
    John Baptiste Lamack was the first to attempt to explain how evolution happens.
  28. Inheritance of
    acquired
    characteristics:
    traits acquired during life passed on to offspring (Lamarck's ideas)
  29. George Cuvier
    introduced the concept of extinction and the theory of catastrophism
  30. Catastrophism
    • The view that the earth’s geological landscape is the result of violent cataclysmic events.
    • Old species have become extinct through these cataclysmic events and are replaced with newly created species.
    • Cuvier promoted this view, especially in opposition to Lamarck.
  31. Charles Lyell
    • Geologist
    • Uniformitarianism
    • Immensity of geologic time
  32. Uniformitarianism
    • The theory that the earth’s features are the result of long term processes that continue to operate in the present as they did in the past.
    • Elaborated on by Lyell, this theory opposed catastrophism and contributed strongly to the concept of immense geological time.
  33. Thomas Malthus
    • Economist
    • Interested in factors causing population increase and decrease.
    • Populations increase exponentially while food supplies stay the same.
    • Always more people born than can survive on the available resources.
    • Results in a struggle for survival.
  34. Mary Anning
    • Discovered the first complete fossil of Ichthyosaurus, a large fishlike marine reptile.
    • She became known as one of the world’s leading “fossilists” and contributed to the understanding of the evolution of marine life over 200 million years ago.
  35. Processes of Natural Selection
    • Species can produce offspring at a faster rate than food supplies increase.
    • There is biological variation within all species.
    • In each generation, more individuals are produced than can survive.
  36. Processes of Natural Selection (continued)
    • Individuals that possess favorable traits or variations are more likely to survive and produce offspring.
    • Environmental context determines whether a trait is beneficial.
    • Traits are inherited and passed on to the next generation.
  37. Processes of Natural Selection #3
    • Variations accumulate over long periods of time, so later generations may be distinct from ancestral ones.
    • As populations respond to pressures over time, they may become distinct species, descended from a common ancestor.
  38. Alfred Russell Wallace (1823-1913)‏
    • Independently developed theory of Natural Selection
    • A naturalist who worked in South America and Southeast Asia.
    • Suggested species descended from other species and new species were influenced by environmental factors.
    • Presented paper on evolution and natural selection to the Linnean Society of London jointly with Darwin.
  39. The Cell
    • Basic unit of life
    • Prokaryotic cells = single celled organisms
    • –appeared 3.7 bya
    • Eukaryotic cells
    • –Have nucleus
    • –appeared 1.2bya (possibly even 3bya)
    • Human body has 1,000 billion (1,000,000,000,000) cells
  40. Structure of a Eukaryotic Cell
    • Cell membrane
    • Organelles
    • Ribosomes-manufacture proteins
    • Mitochondria-generate cell’s energy
    • Nucleus
    • DNA & RNA (genetic material)
  41. 2 Types of Eukaryotic Cells
    • Somatic - body tissues
    • Gametes - sex cells
    • –Ovum (egg)‏
    • –Sperm
    • –Zygote - union between a sperm and an ovum.
  42. DNA: The Genetic Code
    • DNA molecule provides:
    • Codes for the building of biological structures
    • The means to translate this code.
    • Information for operating, maintaining and repairing organisms.
  43. DNA Structure
    • DNA: 2 strands arranged in a double helix held by chemical bases.
    • Sugar-Phosphate strands held together by nitrogen bases
    • Nucleotide: Sugar molecule (deoxyribose), phosphate unit and base
  44. 4 DNA Bases
    • Adenine
    • Thymine
    • Cytosine
    • Guanine
    • A only binds with T
    • C only binds with G
    • The bases provide the instructions for the structures and functions
    • in your body.
  45. RNA
    • RNA differs from DNA in three important ways:
    • 1.It’s usually single-stranded. (This is true of the forms we discuss, but it’s not true for all.)‏
    • 2.It contains a different type of sugar. (Ribose instead of Deoxyribose)‏It contains the base uracil as a substitute for the DNA base thymine. (Uracil (U) is attracted to Adenine (A) , just as Thymine (T) is.)
  46. 3 types of RNA
    • mRNA (messenger RNA) carries message of DNA base sequence from nucleus to cytoplasm
    • Codon: 3 base unit coding for specific amino acid

    • tRNA (transfer RNA) transports amino acid to ribosome
    • Anticodon: 3 base unit in tRNA, complements specific codons

    rRNA (ribosomal RNA) stabilizes mRNA and tRNA bond during protein synthesis
  47. DNA has two main functions
    • Replication
    • Protein production
  48. The DNA Replication Process
    • 1.Enzymes break the bonds between the DNA molecule.
    • 2.Two nucleotide chains serve as templates for the formation of a new strand of nucleotides.
    • 3.Unattached nucleotides pair with the appropriate complementary nucleotide
    • 4.The result is two newly formed strands of DNA.
    • 5.Each new strand is joined to one of the original strands of DNA.
  49. PROTEIN SYNTHESIS: An Essential Function of DNA
    • Amino acids link to form a polypeptide chain.
    • Protein = one or more polypeptide chains folded into a complex structure
    • Protein functions:
    • Structural components of tissues
    • Enzymes
    • Hormones
    • Regulatory proteins
  50. Protein Synthesis: Step One Transcription
    • •The process of coding a genetic message for proteins by formation of mRNA.
    • •A portion of the DNA unwinds and serves as a template for the formation of a mRNA strand.
    • •Each DNA triplet (3 consecutive bases) codes for one specific amino acid
  51. Protein Synthesis: Step Two Translation
    • Messenger RNA leaves the nucleus and attaches to a ribosome.
    • Transfer RNA carries over the appropriate amino acid.
  52. Protein Synthesis: Step Two Translation (continued)
    The process continues until the entire mRNA sequence has been read and a chain of amino acids has been formed.
  53. Junk DNA
    • •Non-coding portions of DNA
    • •Makes up about 98% of our DNA
    • •The remaining 2% are called genes
  54. Genes
    • •Portion of DNA that codes for a polypeptide chain.
    • •Not all DNA contains genes.
    • •Even within genes, there are coding and non-coding portions. (Introns and Exons)
  55. Genes (continuation)
    • Much of our DNA is made up of non-coding sequences
    • Genes contain both sections coding for amino acids (exons) and sections that do not code for amino acids (introns)‏
  56. Regulatory Genes
    • Genes that regulate the expression of other genes.
    • Regulatory proteins turn genes on and off.
    • Allows cells to become specialized.
    • Accounts for the fact that species with very similar DNA can look vastly different.
  57. Regulatory Genes (continuation)
    • •Genes that regulate the expression of other genes.
    • •Allows cells to become specialized.
    • •Accounts for the fact that species with very similar DNA can look vastly different.
  58. DNA Structure
    • •DNA: 2 strands arranged in a double helix held by chemical bases.
    • •Sugar-Phosphate strands held together by nitrogen bases
  59. Nucleotide:
    •Sugar molecule (deoxyribose), phosphate unit and base
  60. Chromosomes
    • Pieces of DNA wound up around proteins.
    • Two copies of each chromosome (one from mom, one from dad)
    • Pairs of chromosomes are called Homologous.
    • Different species have different numbers of chromosomes.
    • Humans have 46 (23 pairs) of chromosomes in every normal somatic cell.
  61. Homologous Chromosomes
    • Chromosomes occur in pairs (one copy from mom and one from dad)
    • Homologous chromosomes will have the same types of genes but may not be genetically identical (genes come in different variations).
  62. Allele
    alternate form of a gene
  63. Sex Chromosomes:
    • chromosomes that determine the individuals sex (X and Y Chromosomes)
    • Females: XX
    • Males: XY
  64. Autosomes:
    any chromosome not involved in sex determination (all chromosomes besides the X and Y chromosomes)
  65. Chromosomes and Genetics
    • Each species has specific chromosome #
    • Humans: 46
    • Chimpanzees: 48
  66. Two types of cells
    • Somatic cells: body tissues
    • Gametes: Sex cells (Sperm and Ovum)
    • Zygote-Union between a sperm and ovum
  67. Diploid
    • Full set of chromosomes – 2 of each
    • –Somatic cells
  68. Haploid
    • ½ set of chromosomes, 1 of each homologous pair
    • –Gametes
  69. Mitosis:
    • Cell division in somatic cells
    • cell division in somatic cells
    • Original cell produces 2 identical (diploid) daughter cells
    • Growth, repair/replacement of tissues.
  70. Meiosis:
    • Cell division in gametes
    • Production of gametes (sex cells).
    • 2 divisions result in 4 non-identical daughter cells.
    • Each daughter cell contains 23 chromosomes.
    • Resulting gamete may unite with another gamete to create a zygote.
    • The zygote inherits the DNA, half from each parent, to develop and function normally.
  71. Steps in Mitosis
    • Double stranded pairs of chromosomes line up at cell center
    • Chromosomes strands split, move to opposite ends
    • Cell membrane pinches, 2 identical cells formed
  72. Recombination (crossing over)
    The exchange of genetic material between homologous chromosomes during meiosis.
  73. Evolutionary Significance of Meiosis
    • Natural selection acts on variation
    • Meiosis increases genetic variation
    • Shuffling of chromosomes
    • Recombination (Crossing over)‏
  74. Problems with meiosis
    • Non-disjunction-the failure of homologous chromosomes or chromosome strands to separate during cell division
    • · Trisomy-extra chromosome
    • · Monosomy-missing chromosome
  75. Down SyndromeTrisomy 21
    • Extra copy of 21st chromosome
    • Cognitive impairment
    • Small chin
    • Round face
    • Almond shaped eyes
    • Large tongue
    • Heart defects
    • Only autosomal trisomy allowing survival to adulthood
  76. Turner Syndrome—X0
    • Absence of sex chromosome
    • Biologically female
    • Short stature
    • Broad chest
    • Webbed neck
    • Low set ears
    • Non-functional reproductive organs
  77. Klinefelter’s Syndrome(XXY)
    • Male with extra X chromosome
    • Small testicles
    • Reduced fertility
    • Feminine characteristics
  78. XYY Syndrome
    • Male with extra Y chromosome
    • Taller than average
    • No obvious abnormalities
  79. Cri-du chat (Cat’s cry) syndrome
    • Missing portion of chromosome 5
    • Abnormal development of vocal tract, also affects mental and facial development
  80. Prader-Willi Syndrome
    • Missing portion of chromosome 15
    • Weak as infants, poor sucking reflex
    • By age 5 or 6, compulsive eating
  81. Mutation:
    Change in the genetic code
  82. Gregor Mendel: Basis of Genetic Inheritance
    • •Austrian priest
    • •(1822-1884)‏Breeding experiments with pea plants provide the basis of genetic inheritance
  83. How are traits controlled?
    • Traits are controlled by discrete units (genes), not blending inheritance
    • These units (genes) occur in pairs.
    • Members of pairs separate into different sex cells and combine again when an egg and sperm cell some together.
    • different gene variants (alleles) represented by letters
    • Some genes are dominant and others are recessive
  84. Recessive:
    • Trait not expressed when another allele is present (t)‏
    • -For a recessive allele to be expressed, there must be two copies of the allele.
    • -Denoted by a lowercase letter
  85. Dominant:
    • Trait that can be expressed in the presence of another (T)‏
    • -Dominant alleles prevent the expression of recessive alleles.
    • -Denoted by a capital letter
  86. Genotype:
    Particular combination of alleles an individual carries (ex: TT, Tt, tt)
  87. Phenotype:
    Observable characteristics of an organism (Tall, Short)
  88. Homozygous:
    Individual has two copies of the same allele: TT or tt
  89. Heterozygous:
    Individual has copies of two different alleles: Tt
  90. Phenotypic ratio:
    3 tall: 1 short
  91. Genotypic ratio:
    1TT:2Tt:1tt
  92. Mendelian Traits
    • Characteristics that are influenced by one pair of genes (one point in the DNA). Examples include many blood types, such as ABO.
    • Many genetic disorders such as sickle-cell anemia and Tay-Sachs disease are also Mendelian traits.
  93. Mendelian Inheritance in Humans: Genetic Disorders
    • Autosomal Disorders
    • Dominant disorders: 1 copy of allele
    • Recessive disorders: 2 copies of allele
    • Sex-linked disorders disorders that occur on the sex chromosomes (X or Y)‏
    • X-linked
    • Y-linked
  94. Autosomal Dominant Trait:Brachydactyly
    shortened fingers and toes
  95. Autosomal Dominant Trait: Achondroplasia
    • Most common form of dwarfism
    • Cartilage doesn’t grow properly
    • Caused by dominant gene dd=normal, Dd=achondroplastic dwarf, DD=lethal prenatally
  96. Autosomal Recessive Trait: Albinism
    Caused by a lack of melanin production
  97. Sex-linked traits
    • Traits occurring on the X or Y chromosomes.
    • (usually the X-chromosome)
  98. Sex Linkage (X-linked) trait: Hemophilia
    • Inability of the blood to
    • clot or coagulate
  99. Royal Disease
    Hemophilia spread through European royal families through Queen Victoria.
  100. Hemizygous
    • An individual who has only one member of a chromosome pair rather than the usual two
    • Refers to certain X-linked traits in males having just a single X chromosome
    • XhY: male with hemophilia
    • XhXn: female carrier
  101. Non-Mendelian Patterns of Inheritance: Polygenic Traits
    • Polygenic traits: influenced by 2 or more genes.
    • Many different genotypes and phenotypes can result.
    • Continuous traits: series of measurable intermediate forms between 2 extremes
    • §E.g., skin pigmentation, stature
  102. Polygenic traits:
    • influenced by 2 or more genes.
    • Many different genotypes and phenotypes can result.
  103. Continuous traits
    • series of measurable intermediate forms between 2 extremes
    • E.g., skin pigmentation, stature
  104. Pleiotropy:
    • When an allele effects more than one trait
    • Marfan Syndrome
    • Thinness
    • Joint hyper-mobility
    • Limb elongation
    • Lens dislocation
    • Susceptibility to heart disease
  105. Genes and Environment
    • Genes set you genetic potential (ability).
    • Factors in your environment determine whether you will reach that potential.
  106. Modern Evolutionary Theory
    • Evolution is a two step process:
    • 1.Genetic variation must be produced and redistributed throughout a population.
    • 2.Variation is then acted on by natural selection.
  107. A Current Definition Of Evolution
    From a modern genetic perspective, we define evolution as a change in allele frequency from one generation to the next.
  108. Gene pool
    • A gene pool is the sum of all the individual genes in a given population.
    • Within a gene pool, every allele (gene variant) has a particular ratio or frequency.
    • When frequencies of alleles change we call this EVOLUTION
  109. Frequency of the ABO alleles
    • Generation one:
    • A=50%
    • B=20%
    • O=30%
    • Generation two:
    • A=25%
    • B=25%
    • O=50%
  110. Evolutionary Forces(forces that create and redistribute variation)
    • Mutation
    • Genetic Drift
    • Gene Flow
    • Natural Selection
  111. Mutation
    • Mutation is a molecular alteration in genetic material.
    • Only source of new variations.
    • For a mutation to have evolutionary significance it must occur in a gamete (sex cell).
  112. Mutation (continued)
    • actual change in genetic material, in DNA
    • any particular mutation is rare
  113. Single DNA base mutation
    Base change (point mutation) or insertion or deletion
  114. Change in chromosome structure
    Portion of chromosome deleted or duplicated
  115. Effects of Mutation
    • Can produce new genes/alleles, provide variation for natural selection.
    • Mutations can be helpful, harmful, or neutral.
    • Rare, may not have big effect on evolutionary change.
    • Frequency of new allele can be affected by genetic drift, gene flow, recombination or natural selection.
  116. Genetic Drift
    • Random change in genetic makeup of population
    • Some individuals leave fewer descendant just by chance.
    • small population
    • changes can occur as “accidents”
    • The genes of the next generation will be the genes of the "lucky" individuals, not necessarily the healthier or "better" individuals.
  117. Genetic Drift (continued)
    • population with blue and green eyed people avalanche kills all blue eyed people
    • lleft with only green eyed people
  118. Genetic Drift—Founder Effect
    • have population with mixture of genes
    • small group leaves to found new population
    • by chance, have unusual allele frequencies
    • new population will have unusual allele frequencies—”sampling error”
  119. Gene Flow
    • interbreeding between people from different populations
    • small scale: adjacent populations exchange mates
    • larger scale: large migrations
  120. Natural selection:
    differential survival and reproductive success of some individuals over others due to possession of favorable traits
  121. Adaptation
    Any trait (physical, biochemical or behavioral), resulting from natural selection, giving an advantage
  122. Sickle Cell Anemia
    Frequently fatal before reproductive age if not treated (no cure yet)‏

    AA AS SS (die from SCA)‏

    But in tropical Africa, Arabian Peninsula, India, S. Europe, freq of S allele can reach 0.16 or more.
  123. Population Genetics
    The study of the frequency of alleles, genotypes, and phenotypes in populations.
  124. Microevolution:
    changes in the frequency of alleles from one generation to the next.
  125. Macroevolution
    the change from one species to another.
  126. Steps in population genetics
    • 1.Measure the allele and genotype frequencies in our population for a specific trait.
    • Ex: figure out the frequencies of the genes for eye color B and b.
    • 2.Figure out what these same frequencies should look like if the population is NOT evolving.
    • 3.Compare the actual frequencies with the hypothetical ones.
    • If the numbers are the same the population is not evolving at this gene.
  127. Steps in population genetics (continuation)
    • Measure the allele and genotype frequencies in our population for a specific trait.
    • Ex: figure out the frequencies of the genes for eye color B and b.
    • Figure out what these same frequencies should look like if the population is NOT evolving.
    • Compare the actual frequencies with the hypothetical ones.
    • If the numbers are the same the population is not evolving at this gene.
  128. Genotype Frequency:
    • •Measure of the relative proportions of different genotypes
    • •# of individuals with each genotype divided by total # of individuals

    • •People with Bb: 50
    • •People in the population: 100
    • •Genotypic frequency of Bb: .5 or 50%
  129. Phenotype Frequency:
    • •Measure of the relative proportions of different phenotypes
    • •# of individuals with each phenotype divided by total # of individuals

    • •People with Blue eyes: 50
    • •People in the population: 100
    • •Phenotypic frequency of Blue eye: .5 or 50%
  130. Allele Frequency:
    • •Relative proportions of different alleles
    • •# of each allele divided by the total # of alleles

    • •B alleles in the population: 50
    • •People in the population: 100
    • •Total alleles in the population: 200
    • •Allele frequency for B: .25 or 25%
  131. Evolution occurs when gene frequencies change
    • In the absence of evolutionary forces, allele frequencies will remain constant over time
    • The Population will be in Equilibrium
    • A population may be in equilibrium for a certain gene but will never be in complete equilibrium for all of its genes.
  132. Hardy-Weinberg Principle
    G. Hardy and W. Weinberg proposed that the frequency of alleles and genotypes in a population will remain constant if the population is in genetic equilibrium.
  133. Hardy-Weinberg Principle
    • Five conditions are required in order for a population to remain at eqiulibrium.
    • 1.Large population (i.e. no genetic drift)
    • 2.Random mating
    • 3.No mutation
    • 4.No gene flow
    • 5.No natural Selection
  134. Large Population
    A large breeding population helps to ensure that chance alone does not disrupt genetic equilibrium. In a small population, only a few copies of a certain allele may exist.
  135. 2. Random Mating
    In assortative (non-random) mating, individuals tend to choose mates similar to themselves.Results in fewer heterozygous individuals than you would expect in a population where mating is random
  136. 3. No Mutation
    Any mutation in a particular gene would change the balance of alleles in the gene pool.
  137. 4. No Gene Flow
    For the allelic frequency to remain constant in a population at equilibrium, no new alleles can come into the population, and no alleles can be lost. Both immigration and emigration can alter allelic frequency
  138. 5. No Natural Selection
    • If selection occurs, those alleles that are selected for will become more common.
    • §For example, if a weed is resistant to herbicide, the allele for resistance may become more frequent in the population.
  139. Hardy-Weinberg Equation
    • The mathematical equation expressing the predicted frequencies of alleles in a population if that population is in equilibrium.
    • Provides a tool to establish whether allele frequencies in a human population are changing.
  140. Hardy Weinberg Equation
    Alleles- A & a

    • Frequency of dominant allele (A)=p
    • Frequency of recessive allele (a)=q
    • p+q=1 (100% of alleles)‏

    • Expected frequency of AA = p2
    • Expected frequency of aa = q2
    • Expected frequency of Aa = 2pq

    p2 + 2pq + q2 = 1 (100% of the expected genotypes)

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