09 lecture presentation

1,217 views
878 views

Published on

Published in: Science, Lifestyle, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,217
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
8
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide
  • Figure 9.1 Gregor Mendel.
  • Figure 9.2 The structure of a pea flower.
  • Figure 9.3 Mendel's technique for cross-fertilizing pea plants. (Step 1)
  • Figure 9.3 Mendel's technique for cross-fertilizing pea plants. (Step 2)
  • Figure 9.3 Mendel's technique for cross-fertilizing pea plants. (Step 3)
  • Figure 9.4 The seven characters of pea plants studied by Mendel.
  • Figure 9.5 Mendel's cross tracking one character (flower color). (Step 1)
  • Figure 9.5 Mendel's cross tracking one character (flower color). (Step 2)
  • Figure 9.5 Mendel's cross tracking one character (flower color). (Step 3)
  • Figure 9.5 Photo of Mendel in garden.
  • Figure 9.6 The law of segregation. (Step 1)
  • Figure 9.6 The law of segregation. (Step 2)
  • Figure 9.6 The law of segregation. (Step 3)
  • Figure 9.7 The relationship between alleles and homologous chromosomes.
  • Figure 9.10 A Labrador retriever testcross
  • Figure 9.12a Examples of inherited traits thought to be controlled by a single gene.
  • Figure 9.12b Examples of inherited traits thought to be controlled by a single gene.
  • Figure 9.12c Examples of inherited traits thought to be controlled by a single gene.
  • Figure 9.13 A family pedigree showing inheritance of free versus attached earlobes.
  • Figure 9.13a A family pedigree showing inheritance of free versus attached earlobes.
  • Figure 9.13b A family pedigree showing inheritance of free versus attached earlobes.
  • Figure 9.13c A family pedigree showing inheritance of free versus attached earlobes.
  • Table 9.1 Some Autosomal Disorders in Humans
  • Figure 9.14 Predicted offspring when both parents are carriers for a recessive disorder.
  • Figure 9.15 Achondroplasia, a dominant trait.
  • Figure 9.16 A family with and without achondroplasia.
  • Figure 9.16a A family with and without achondroplasia.
  • Figure 9.16b A family with and without achondroplasia.
  • Figure 9.18 Incomplete dominance in snapdragons. (Step 1)
  • Figure 9.18 Incomplete dominance in snapdragons. (Step 2)
  • Figure 9.18 Incomplete dominance in snapdragons. (Step 3)
  • Figure 9.23 As a result of environmental influences, even identical twins can look different.
  • Figure 9.29 The chromosomal basis of sex determination.
  • Figure 9.30 A test for red-green colorblindness.
  • Figure 9.31 Inheritance of colorblindness, a sex-linked recessive trait.
  • Figure 9.32 Hemophilia in the royal family of Russia.
  • Figure 9.UN1 Summary: Law of Segregation
  • Figure 9.UN2 Summary: Testcross
  • Figure 9.UN3 Summary: Incomplete Dominance
  • Figure 9.UN4 Summary: Pleiotropy
  • Figure 9.UN5 Summary:Polygenic Inheritance
  • Figure 9.UN6 Summary: Sex Determination in Humans
  • Figure 9.UN7 Summary: Sex Linked Traits
  • 09 lecture presentation

    1. 1. © 2010 Pearson Education, Inc. • Heredity is the transmission of traits from one generation to the next. • Gregor Mendel – Worked in the 1860s – Was the first person to analyze patterns of inheritance – Deduced the fundamental principles of genetics HERITABLE VARIATION AND PATTERNS OF INHERITANCE
    2. 2. Figure 9.1
    3. 3. © 2010 Pearson Education, Inc. In an Abbey Garden • Mendel studied garden peas because they – Are easy to grow – Come in many readily distinguishable varieties – Are easily manipulated – Can self-fertilize
    4. 4. Carpel (produces eggs) Stamen (makes sperm- producing pollen) Petal Figure 9.2
    5. 5. © 2010 Pearson Education, Inc. • A character is a heritable feature that varies among individuals. • A trait is a variant of a character. • Each of the characters Mendel studied occurred in two distinct forms.
    6. 6. © 2010 Pearson Education, Inc. • Mendel – Created true-breeding varieties of plants – Crossed two different true-breeding varieties • Hybrids are the offspring of two different true-breeding varieties. – The parental plants are the P generation. – Their hybrid offspring are the F1 generation. – A cross of the F1 plants forms the F2 generation.
    7. 7. Removed stamens from purple flower. White Stamens Purple Transferred pollen from stamens of white flower to carpel of purple flower. Parents (P) Carpel Figure 9.3-1
    8. 8. Removed stamens from purple flower. White Stamens Purple Transferred pollen from stamens of white flower to carpel of purple flower. Parents (P) Carpel Pollinated carpel matured into pod. Figure 9.3-2
    9. 9. Removed stamens from purple flower. White Stamens Purple Transferred pollen from stamens of white flower to carpel of purple flower. Parents (P) Carpel Offspring (F1) Pollinated carpel matured into pod. Planted seeds from pod. Figure 9.3-3
    10. 10. © 2010 Pearson Education, Inc. Mendel’s Law of Segregation • Mendel performed many experiments. • He tracked the inheritance of characters that occur as two alternative traits.
    11. 11. WhitePurple RecessiveDominant GreenYellow TerminalAxial WrinkledRound Green Yellow Seed shape Seed color Flower position Flower color Pod color RecessiveDominant Pod shape Stem length Inflated Constricted Tall Dwarf Figure 9.4
    12. 12. © 2010 Pearson Education, Inc. Monohybrid Crosses • A monohybrid cross is a cross between parent plants that differ in only one character. Blast Animation: Single-Trait Crosses
    13. 13. Purple flowers White flowers P Generation (true-breading parents) Figure 9.5-1
    14. 14. Purple flowers F1 Generation White flowers P Generation (true-breading parents) All plants have purple flowers Figure 9.5-2
    15. 15. Purple flowers F1 Generation White flowers P Generation (true-breading parents) All plants have purple flowers F2 Generation Fertilization among F1 plants (F1 × F1) of plants have purple flowers of plants have white flowers 3 4 1 4 Figure 9.5-3
    16. 16. Figure 9.5
    17. 17. © 2010 Pearson Education, Inc. • Mendel developed four hypotheses from the monohybrid cross: 1. There are alternative versions of genes, called alleles. 2. For each character, an organism inherits two alleles, one from each parent. – An organism is homozygous for that gene if both alleles are identical. – An organism is heterozygous for that gene if the alleles are different.
    18. 18. © 2010 Pearson Education, Inc. 3. If two alleles of an inherited pair differ – The allele that determines the organism’s appearance is the dominant allele – The other allele, which has no noticeable effect on the appearance, is the recessive allele
    19. 19. © 2010 Pearson Education, Inc. 4. Gametes carry only one allele for each inherited character. – The two members of an allele pair segregate (separate) from each other during the production of gametes. – This statement is the law of segregation.
    20. 20. © 2010 Pearson Education, Inc. • Do Mendel’s hypotheses account for the 3:1 ratio he observed in the F2 generation? • A Punnett square highlights the four possible combinations of gametes and offspring that result from each cross. Blast Animation: Genetic Variation: Fusion of Gametes
    21. 21. Purple flowers White flowers P Generation Genetic makeup (alleles) Gametes Alleles carried by parents PP P pp pAll All Figure 9.6-1
    22. 22. Purple flowers F1 Generation (hybrids) White flowers P Generation Genetic makeup (alleles) Gametes Alleles carried by parents PP P pp pAll All All Pp Purple flowers Gametes Alleles segregate P p1 2 1 2 Figure 9.6-2
    23. 23. Purple flowers F1 Generation (hybrids) White flowers P Generation Genetic makeup (alleles) Gametes Alleles carried by parents PP P pp pAll All All Pp Purple flowers Gametes Alleles segregate P p F2 Generation (hybrids) Sperm from F1 plant P p P p PP pp Pp Pp Eggs from F1 plant Phenotypic ratio 3 purple : 1 white Genotypic ratio 1 PP : 2 Pp : 1 pp 1 2 1 2 Figure 9.6-3
    24. 24. © 2010 Pearson Education, Inc. • Geneticists distinguish between an organism’s physical traits and its genetic makeup. – An organism’s physical traits are its phenotype. – An organism’s genetic makeup is its genotype.
    25. 25. © 2010 Pearson Education, Inc. Genetic Alleles and Homologous Chromosomes • Homologous chromosomes have – Genes at specific loci – Alleles of a gene at the same locus
    26. 26. Homologous chromosomes P Genotype: Gene loci P a aa b B Dominant allele Recessive allele BbPP Homozygous for the dominant allele Homozygous for the recessive allele Heterozygous a Figure 9.7
    27. 27. © 2010 Pearson Education, Inc. Mendel’s Law of Independent Assortment • A dihybrid cross is the crossing of parental varieties differing in two characters. Blast Animation: Two-Trait Crosses
    28. 28. Using a Testcross to Determine an Unknown Genotype • A testcross is a mating between – An individual of dominant phenotype (but unknown genotype) – A homozygous recessive individual © 2010 Pearson Education, Inc.
    29. 29. Two possible genotypes for the black dog: B_ bb Testcross Genotypes Bb B b orBB B b Bb Bb bbb Gametes Offspring All black 1 black : 1 chocolate Figure 9.10
    30. 30. © 2010 Pearson Education, Inc. Family Pedigrees • Mendel’s principles apply to the inheritance of many human traits.
    31. 31. Freckles No freckles Figure 9.12a
    32. 32. Widow’s peak Straight hairline Figure 9.12b
    33. 33. Free earlobe Attached earlobe Figure 9.12c
    34. 34. © 2010 Pearson Education, Inc. • Dominant traits are not necessarily – Normal or – More common
    35. 35. © 2010 Pearson Education, Inc. • A family pedigree – Shows the history of a trait in a family – Allows geneticists to analyze human traits
    36. 36. Female Male Attached Free Third generation (brother and sister) Second generation (parents, aunts, and uncles) First generation (grandparents) Ff Ff FfFF ff ff or Ff ff FF or Ff Ffff Ff ff Figure 9.13
    37. 37. Figure 9.13a
    38. 38. Figure 9.13b
    39. 39. Figure 9.13c
    40. 40. © 2010 Pearson Education, Inc. Human Disorders Controlled by a Single Gene • Many human traits – Show simple inheritance patterns – Are controlled by single genes on autosomes
    41. 41. Table 9.1
    42. 42. © 2010 Pearson Education, Inc. Recessive Disorders • Most human genetic disorders are recessive. • Individuals who have the recessive allele but appear normal are carriers of the disorder.
    43. 43. Parents Offspring Dd Hearing Hearing Dd Sperm Eggs D Hearing D Dd d Hearing (carrier) DD Dd Hearing (carrier) dd Deaf d Figure 9.14
    44. 44. © 2010 Pearson Education, Inc. • Cystic fibrosis – Is the most common lethal genetic disease in the United States – Is caused by a recessive allele carried by about one in 25 people of European ancestry
    45. 45. © 2010 Pearson Education, Inc. Dominant Disorders • Some human genetic disorders are dominant. – Huntington’s disease, which leads to degeneration of the nervous system, does not begin until middle age. – Achondroplasia is a form of dwarfism. – The homozygous dominant genotype causes death of the embryo. – Thus, only heterozygotes have this disorder.
    46. 46. Figure 9.15
    47. 47. Parents Sperm Eggs d Dwarf D Dd d Dd dd d Normal (no achondroplasia) Molly Jo Dwarf (achondroplasia) Dddd Normal dd Normal Dwarf Matt Amy JakeZachary Jeremy Figure 9.16
    48. 48. Parents Sperm Eggs d Dwarf D Dd d Dd dd d Normal (no achondroplasia) Dwarf (achondroplasia) Dddd Normal dd Normal Dwarf Figure 9.16a
    49. 49. Molly Jo Matt Amy JakeZachary Jeremy Figure 9.16b
    50. 50. © 2010 Pearson Education, Inc. Genetic Testing • Today many tests can detect the presence of disease-causing alleles. • Most genetic testing is performed during pregnancy. – Amniocentesis collects cells from amniotic fluid. – Chorionic villus sampling removes cells from placental tissue. • Genetic counseling helps patients understand the results and implications of genetic testing.
    51. 51. © 2010 Pearson Education, Inc. VARIATIONS ON MENDEL’S LAWS • Some patterns of genetic inheritance are not explained by Mendel’s laws.
    52. 52. © 2010 Pearson Education, Inc. Incomplete Dominance in Plants and People • In incomplete dominance, F1 hybrids have an appearance in between the phenotypes of the two parents.
    53. 53. RR rr P Generation Gametes Red White R r Figure 9.18-1
    54. 54. F1 Generation RR rr Gametes P Generation Gametes Red White R r Rr Pink R r 1 2 1 2 Figure 9.18-2
    55. 55. F1 Generation RR rr Gametes P Generation F2 Generation Sperm Gametes Red White R r Rr Pink R r R r R r RR Rr rrRr Eggs 1 2 1 2 1 2 1 2 1 2 1 2 Figure 9.18-3
    56. 56. ABO Blood Groups: An Example of Multiple Alleles and Codominance • The ABO blood groups in humans are an example of multiple alleles. © 2010 Pearson Education, Inc.
    57. 57. © 2010 Pearson Education, Inc. Pleiotropy and Sickle-Cell Disease • Pleiotropy is the impact of a single gene on more than one character. • Sickle-cell disease – Exhibits pleiotropy – Results in abnormal hemoglobin production – Causes disk-shaped red blood cells to deform into a sickle shape with jagged edges
    58. 58. © 2010 Pearson Education, Inc. Polygenic Inheritance • Polygenic inheritance is the additive effects of two or more genes on a single phenotype.
    59. 59. Figure 9.23
    60. 60. © 2010 Pearson Education, Inc. The Role of Environment • Many human characters result from a combination of heredity and environment. • Only genetic influences are inherited.
    61. 61. © 2010 Pearson Education, Inc. Linked Genes • Linked genes – Are located close together on a chromosome – May be inherited together
    62. 62. © 2010 Pearson Education, Inc. Linkage Maps • Early studies of crossing over were performed using the fruit fly Drosophila melanogaster. • Alfred H. Sturtevant, a student of Morgan, developed a method for mapping gene loci, which resulted in the creation of linkage maps. – A diagram of relative gene locations on a chromosome is a linkage map.
    63. 63. ColorizedSEM Y X Figure 9.29
    64. 64. © 2010 Pearson Education, Inc. SEX CHROMOSOMES AND SEX-LINKED GENES • Sex chromosomes influence the inheritance of certain traits.
    65. 65. © 2010 Pearson Education, Inc. Sex Determination in Humans • Nearly all mammals have a pair of sex chromosomes designated X and Y. – Males have an X and Y. – Females have XX.
    66. 66. © 2010 Pearson Education, Inc. Sex-Linked Genes • Any gene located on a sex chromosome is called a sex-linked gene. – Most sex-linked genes are found on the X chromosome. – Red-green color blindness is a common human sex-linked disorder.
    67. 67. Figure 9.30
    68. 68. Unaffected individual Sperm Eggs XN XN Xn Y Xn Y Sperm XN Xn XN Y XN Y Sperm XN Xn Xn Y Xn Y XN Xn XN YXN XN XN Xn XN Y Eggs XN XN XN YXN Xn Xn YXN Xn Eggs XN Xn XN YXN Xn Xn YXn Xn Normal female × colorblind male Key (a) Carrier female × normal male (b) Carrier female × colorblind male (c) Colorblind individualCarrier Figure 9.31
    69. 69. © 2010 Pearson Education, Inc. • Hemophilia – Is a sex-linked recessive blood-clotting trait that may result in excessive bleeding and death after relatively minor cuts and bruises – Has plagued royal families of Europe
    70. 70. AlbertQueen Victoria Alice Louis Alexandra Czar Nicholas II of Russia Alexis Figure 9.32
    71. 71. © 2010 Pearson Education, Inc. • In 2005 researchers sequenced the complete genome of a dog. • An evolutionary tree of dog breeds was created.
    72. 72. Meiosis Haploid gametes (allele pairs separate) Diploid cell (contains paired alleles, alternate forms of a gene) Diploid zygote (contains paired alleles) Gamete from other parent Alleles Fertilization Figure 9.UN1
    73. 73. Phenotype P ? Phenotype Genotype Conclusion RecessiveDominant pp All dominant or Unknown parent is PP 1 dominant : 1 recessive Unknown parent is Pp Figure 9.UN2
    74. 74. Dominant phenotype (RR) Recessive phenotype (rr) Intermediate phenotype (incomplete dominance) (Rr) Figure 9.UN3
    75. 75. Pleiotropy Multiple traits (e.g., sickle-cell disease) Single gene Figure 9.UN4
    76. 76. Multiple genes Polygenic inheritance Single trait (e.g., skin color) Figure 9.UN5
    77. 77. Female Somatic cells Male 44 + XY 44 + XX Figure 9.UN6
    78. 78. Figure 9.UN7

    ×