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HERITABLE VARIATION & PATTERNS OF INHERITANCE•“Wild type” traits are traits most commonlyfound in nature                  ...
• Various traits exist in organismsx  These traits are usually inherited in particular patterns 03/12/12                 ...
Parents:                           X                                                 X                                    ...
Mendelian Genetics• Gregor Mendel   G  Was the first to      analyze patterns of      inheritance   –  Deduced the      ...
In an Abbey Garden• Mendel studied  garden peas  e  These plants     are easily     manipulated  –  These plants     can...
Mendelian                                   White                               1 Removed             Genetics            ...
Mendelian Genetics• He also created true-breeding varieties of  plants  Mendel then crossed two different true-breeding  v...
Mendel’s Principles of Segregation  • Mendel performed many experiments He tracked several characteristics in pea plants ...
Traits in Pea Plants                  Dominant   Recessive                 Dominant    Recessive                          ...
Monohybrid Crosses                         P Generation• A monohybrid           (true-breeding                         par...
• Mendel developed four hypotheses from the  monohybrid cross: – 1) There are alternative forms of genes, now   called all...
Mendel’s Results                                              Genetic makeup (alleles)                   P plants         ...
Describing Traits:• Phenotype  s  An organism’s physical traits• Genotype  •  An organism’s genetic makeup  03/12/12    ...
Mendel’s Principle of Segregation       Pairs of alleles segregate (separate) during      gamete formation; the fusion of...
Genetic Alleles & Homologous Chromosomes• Homologous chromosomes: &  Have genes at specific loci  (locations on the chrom...
Genetic Alleles & Homologous Chromosomes                       Homologous chromosomes:                                 Gen...
Genetic Alleles & Homologous             Chromosomes• Homozygous  s  When an organism has identical alleles for a     gen...
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Hereditary patterns

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Transcript of "Hereditary patterns"

  1. 1. HERITABLE VARIATION & PATTERNS OF INHERITANCE•“Wild type” traits are traits most commonlyfound in nature Figure 9.2 03/12/12 1
  2. 2. • Various traits exist in organismsx  These traits are usually inherited in particular patterns 03/12/12 2
  3. 3. Parents: X X Parents: Wild-type Wild-type Wild-type Sky-blue First- wild-type Offspring: All All Wild-type generation offspring: Matings Second- generation (a) Offspring from the mating offspring: 3/4 and /4 1 of two wild-type birds Wild-type Sky-blue (b) Two generations of offspring from the mating of a wild-type with a sky-blue bird Figure 9.3 03/12/12 3
  4. 4. Mendelian Genetics• Gregor Mendel G  Was the first to analyze patterns of inheritance –  Deduced the fundamental principles of genetics Figure 9.4 03/12/12 4
  5. 5. In an Abbey Garden• Mendel studied garden peas e  These plants are easily manipulated –  These plants can self-fertilize stamen Stamen Carpel carpel Figure 9.5 03/12/12 5
  6. 6. Mendelian White 1 Removed Genetics stamens from purple flower• Mendel carried out Stamens some cross- Carpel 2 Transferred pollen from stamens of fertilization Parents (P) Purple white flower to carpel of purple flower 3 Pollinated carpel matured into pod 4 Planted seeds from pod Offspring (F1) Figure 9.6 03/12/12 6
  7. 7. Mendelian Genetics• He also created true-breeding varieties of plants Mendel then crossed two different true-breeding varieties, creating hybrids 03/12/12 7
  8. 8. Mendel’s Principles of Segregation • Mendel performed many experiments He tracked several characteristics in pea plants fromwhich he formulated several hypotheses 03/12/12 8
  9. 9. Traits in Pea Plants Dominant Recessive Dominant Recessive Pod shape Inflated ConstrictedFlower color Purple White Pod Color Green YellowFlower position Axial TerminalSeed color Yellow Green Stem length Tall DwarfSeed shape Round Wrinkled Figure 9.7 03/12/12 9
  10. 10. Monohybrid Crosses P Generation• A monohybrid (true-breeding parents) Purple White cross is a cross flowers flowers between parent F1 Generation All plants have plants that differ purple flowers in only one among F1 plants characteristic (F1 × F1) Fertilization F2 Generation 1 /4 of plantsHave 3 /4 of plants have whiteflower purple flowers s (a) Mendel’s crosses tracking one characteristic (flower color) Figure 9.8a 03/12/12 10
  11. 11. • Mendel developed four hypotheses from the monohybrid cross: – 1) There are alternative forms of genes, now called alleles – 2) For each characteristic, each organism has two genes – 3) Gametes carry only one allele for each inherited characteristic – 4) Alleles can be dominant or recessive 03/12/12 11
  12. 12. Mendel’s Results Genetic makeup (alleles) P plants PP PP• Including a Gametes All P All p Punnett square F1 plants: (hybrids) All Pp Gametes 1 /2 P 1 /2 p Eggs P P Sperm F2 plants: p PP p Phenotypic ratio Pp Pp 3 purple : 1 white pp Genotypic ratio 1 PP : 2 Pp : 1 pp (b) Explanation of the results in part (a) Figure 9.8b 03/12/12 12
  13. 13. Describing Traits:• Phenotype s  An organism’s physical traits• Genotype •  An organism’s genetic makeup 03/12/12 13
  14. 14. Mendel’s Principle of Segregation  Pairs of alleles segregate (separate) during gamete formation; the fusion of gametes at fertilization creates allele pairs again 03/12/12 14
  15. 15. Genetic Alleles & Homologous Chromosomes• Homologous chromosomes: &  Have genes at specific loci (locations on the chromosome) –  Have alleles of a gene at the same locus 03/12/12 NCBI Human Ch 21 15
  16. 16. Genetic Alleles & Homologous Chromosomes Homologous chromosomes: Gene loci Dominant allele P a B P a b Recessive allele Genotype: PP aa Bb Homozygous Homozygous Heterozygous for the for the dominant allele recessive allele Figure 9.9 03/12/12 16
  17. 17. Genetic Alleles & Homologous Chromosomes• Homozygous s  When an organism has identical alleles for a gene• Heterozygous -  When an organism has different alleles for a gene 03/12/12 17
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