Mendelian Genetics Gregor Mendel – Austrian monk – performed extensive genetics experiments with garden peas Gregor Mendel – Austrian monk – performed.

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  • Mendelian Genetics Gregor Mendel Austrian monk performed extensive genetics experiments with garden peas Gregor Mendel Austrian monk performed extensive genetics experiments with garden peas http://www.biology.arizona.e du/mendelian_genetics/mend elian_genetics.html http://www.biology.arizona.e du/mendelian_genetics/mend elian_genetics.html http://www.biology.arizona.e du/mendelian_genetics/mend elian_genetics.html http://www.biology.arizona.e du/mendelian_genetics/mend elian_genetics.html http://www.quia.com/jfc/65 851.html http://www.quia.com/jfc/65 851.html http://www.quia.com/jfc/65 851.html http://www.quia.com/jfc/65 851.html
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  • Gregor Mendel
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  • Important Mendelian Genetics terms: trait: physical attribute or characteristic displayed by an individual (i.e. seed shape, seed colour, etc.) trait: physical attribute or characteristic displayed by an individual (i.e. seed shape, seed colour, etc.) allele: forms of a trait (i.e. round or wrinkled allele for the trait seed shape) allele: forms of a trait (i.e. round or wrinkled allele for the trait seed shape) dominant allele: allele that is displayed when both dominant and recessive alleles are present (dominant allele masks the recessive allele) dominant allele: allele that is displayed when both dominant and recessive alleles are present (dominant allele masks the recessive allele) recessive allele: allele that is hidden when both dominant and recessive alleles are present (dominant allele masks the recessive allele), and only expressed when both recessive alleles are present) recessive allele: allele that is hidden when both dominant and recessive alleles are present (dominant allele masks the recessive allele), and only expressed when both recessive alleles are present) genotype: actual gene (allele) combination present (RR or Rr) genotype: actual gene (allele) combination present (RR or Rr) phenotype: physical outward appearance shown (round seed or wrinkled seed) phenotype: physical outward appearance shown (round seed or wrinkled seed)
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  • homozygote: an individual which contains only one allele at the allelic pair; for example DD is homozygous dominant and dd is homozygous recessive; pure lines are homozygous for the gene of interest homozygote: an individual which contains only one allele at the allelic pair; for example DD is homozygous dominant and dd is homozygous recessive; pure lines are homozygous for the gene of interest heterozygote: an individual which contains one of each member of the gene pair; for example the Dd heterozygote heterozygote: an individual which contains one of each member of the gene pair; for example the Dd heterozygote Human Eye color Human Eye color Human Eye color Human Eye color
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  • Multiple Alleles Multiple Alleles the existence of several (more than two) alleles for a gene (e.g. ABO blood group) Multiple Alleles the existence of several (more than two) alleles for a gene (e.g. ABO blood group) Genotype Blood Type (Phenotype) I A I A or I A i A I B I B or I B i B IAIBIAIBIAIBIAIBAB iiO
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  • Incomplete Dominance shown when a heterozygote has a different phenotype (blending of both homozygotes) than either homozygote (e.g. Snapdragons: shown when a heterozygote has a different phenotype (blending of both homozygotes) than either homozygote (e.g. Snapdragons: 2 alleles - Red R, White W RR (red) x WW (white) produce RW (pink) RR (red) x WW (white) produce RW (pink) RED WHITE PINK
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  • Codominance Similar to incomplete dominance Similar to incomplete dominance co together co together recessive & dominant traits appear together in the phenotype of hybrid organisms recessive & dominant traits appear together in the phenotype of hybrid organisms Ex: roan coat color in cattle (red and white hair on same animal) Ex: roan coat color in cattle (red and white hair on same animal) 2 allelles - R red, W white 2 allelles - R red, W white 3 different phenotypes red (RR), white (WW) and roan (RW) 3 different phenotypes red (RR), white (WW) and roan (RW)
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  • X-linked Inheritance X-linked Inheritance Sometimes called sex-link inheritance Sometimes called sex-link inheritance Males XY, Females XX Males XY, Females XX Some traits are present on the X chromosome Some traits are present on the X chromosomeX chromosomeX chromosome E.g. hemophilia X-linked disease (bleeder disease) E.g. hemophilia X-linked disease (bleeder disease) Normal female XX, carrier female XX h Normal female XX, carrier female XX h Female with hemophilia X h X h (only if they have both X h chromosomes) Female with hemophilia X h X h (only if they have both X h chromosomes) Normal male XY, male with hemophilia X h Y Normal male XY, male with hemophilia X h Y Color blindness X-linked Color blindness X-linked
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  • Dihybrid Cross Monohybrid cross dealing with only one trait Monohybrid cross dealing with only one trait Dihybrid cross dealing with two traits (seed shape and seed colour) Dihybrid cross dealing with two traits (seed shape and seed colour) (P 1 )Yellow, round pea plant crossed with wrinkled, green plants produced 100% Yellow, round plants (F 1 - YyRr) (P 1 )Yellow, round pea plant crossed with wrinkled, green plants produced 100% Yellow, round plants (F 1 - YyRr)
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  • F 1 generation crossed YyRr x YyRr F 1 generation crossed YyRr x YyRr Four possible gametes YR, yR, Yr, yr Four possible gametes YR, yR, Yr, yr
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  • F 2 Generation
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  • 9 yellow, round 9 yellow, round 3 green, round 3 green, round 3 yellow, wrinkled 3 yellow, wrinkled 1 green, wrinkled 1 green, wrinkled F2 Generation phenotypic ratio
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  • Mendels Laws Mendels Laws 3 laws: 3 laws: a. Law of dominance In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation. Offspring that are hybrid for a trait will have only the dominant trait in the phenotype. b. Law of segregation - During the formation of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other. Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring. c. Law of independent assortment - Alleles for different traits are distributed to sex cells (& offspring) independently of one another.
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  • Linked Genes Linked Genes Linked genes - genes that are on the same chromosome and subsequently are inherited together as a package unless crossing-over separates them. Linked genes - genes that are on the same chromosome and subsequently are inherited together as a package unless crossing-over separates them. Crossing over - process of sections of homologous chromosomes breaking and reconnecting onto the other homologous chromosome. Crossing over - process of sections of homologous chromosomes breaking and reconnecting onto the other homologous chromosome. Recombination - creation of combinations of alleles in chromosomes not present in either parent. Recombination - creation of combinations of alleles in chromosomes not present in either parent.
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  • Linked Genes??
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  • Crossing Over & Recombination
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  • Hardy Weinberg Equation 1. p + q = 1.0 2. p 2 + 2pq + q 2 = 1.0
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  • Hardy Weinberg Equation p + q = 1 p + q = 1 p2 + 2pq + q2 = 1 p2 + 2pq + q2 = 1 Unibrow is a recessive genetic trait in humans in which it occurs 1 in 30 people. Unibrow is a recessive genetic trait in humans in which it occurs 1 in 30 people. N separate eyebrow N separate eyebrow n - unibrow n - unibrow
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  • 1. q 2 = 1 / 30 = 0.033 2. q = q 2 = 0.033 = 0.183 = 18.3% of the genes in the population are unibrow (nn) 3. p = 1 q = 1- 0.183 = 0.817 = 81.7% of the genes in the population are separate eyebrow. 4. p 2 = 0.8172 = 0.668 = 66.8% of the population is NN. 5. 2pq = 2 (0.817)( 0.183) = 0.298 = 29.8% of the population is Nn (carriers for the unibrow gene)
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  • Probability the study of outcomes of events or occurrences the study of outcomes of events or occurrences Probability = # of chances for an event / # of possible outcomes Probability = # of chances for an event / # of possible outcomes Probability of a red card = (26/52) Probability of a red card = (26/52) Probability of a red 6 = 1/26 (2/52) Probability of a red 6 = 1/26 (2/52) How does this apply to genetics? How does this apply to genetics? Rr - probability of R = , probability of r = Rr - probability of R = , probability of r =

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