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  • Figure: FGTable 11.1 Title: Pea-plant characteristics studied by Mendel. Caption: Pea-plant characteristics studied by Mendel.
  • Figure: FG11-04 Title: Variations within a pea pod. Caption: Since each garden pea is fertilized separately, individual peas within a pod can have different character traits. Note that some of these peas have a smooth texture, while others are wrinkled.
  • Figure: FG11-05a Title: Mendel's F1 crosses. Caption: 1. Mendel started out by cross-breeding plants that for generations had yielded either all yellow seeds or all green seeds. In the example pictured, female gametes are being provided by a plant that has the dominant, yellow alleles (YY), while the male gametes are being provided by a plant has the recessive, green alleles (yy). 2. The cells of the pea plants that give rise to gametes start to go through meiosis. 3. The two alleles for pea color, which lie on separate homologous chromosomes, separate in meiosis, yielding gametes that each bear a single allele for seed color. In the case of the female, each of these gametes bears a Y allele; in the case of the male, each bears a y allele. 4. The Punnett square shows the possible combinations that can result when the male and female gametes come together in the moment of fertilization. (If you have trouble reading the Punnett square, see Figure 11.5b.) The single possible outcome in this fertilization is a mixed genotype, Yy. 5. Because Y (yellow) is dominant over y (green), the result is that all the offspring in the F1 generation are yellow, because they all contain a Y allele.
  • Figure: FG11-07 Title: Three genotypes, two phenotypes. Caption: The two alleles for seed color (Y = yellow and y = green) can result in three genotypes (YY, Yy, yy), but these can yield only two phenotypes (yellow and green).
  • Figure: FG11-06 Title: From the F1 to the F3 generation. Caption: F1 to F2: The starting point is the F1 generation, a set of seeds that all have the Yy genotype. These seeds are planted and the plants go through meiosis, yielding the gametes shown in the Punnett square. When these gametes come together in self-fertilization, the possibilities include YY and yy combinations, as well as the Yy combination seen in the F1 generation. The existence of yy individuals is the reason green seeds reappear in the F2 generation. Because Y is dominant, the green phenotype could not appear in seeds that had even a single Y allele. F2 to F3: With three starting genotypes (YY, Yy, yy) the F2 generation yields plants that have these three genotypes, though there are more plants of "mixed" genotype than of either "pure" genotype.
  • Figure: FGTable 11.2 Title: Pea-plant characteristics studied by Mendel. Caption: Pea-plant characteristics studied by Mendel.
  • There are over 30 common red blood cell antigens The most vigorous transfusion reactions are caused by ABO and Rh blood group antigens Describe atitgen/antibody production, prelude to immune system.
  • Based on the presence or absence of two antigens Type A Type B The lack of these antigens is called type O Blood samples are mixed with anti-A and anti-B serum Coagulation or no coagulation leads to determining blood type Typing for ABO and Rh factors is done in the same manner Cross matching – testing for agglutination of donor RBCs by the recipient’s serum, and vice versa
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    1. 1. <ul><li>Gregor Mendel </li></ul><ul><ul><li>Peas, please </li></ul></ul><ul><li>Segregation of alleles </li></ul><ul><ul><li>Shown by monohybrid crosses </li></ul></ul><ul><li>Independent assortment of alleles </li></ul><ul><ul><li>shown by dihybrid crosses </li></ul></ul>
    2. 3. <ul><li>Gregor Mendel - pea research done 1856-1863 </li></ul>Figure 9.2Ax <ul><li>Basic ideas: </li></ul><ul><li>Genetic elements come in pairs </li></ul><ul><li>Elements do not change </li></ul><ul><li>over generations </li></ul><ul><li>Pairs separate when gametes form </li></ul>
    3. 4. <ul><li>Pea plants: </li></ul><ul><li>Self- or cross-pollinate </li></ul><ul><li>Rapid life cycle </li></ul><ul><li>Variety of traits </li></ul>Figure 9.2C <ul><li>Shown here: cross-fertilization </li></ul>1 Removed stamens from purple flower White Stamens Carpel Purple PARENTS (P) OFF-SPRING (F 1 ) 2 Transferred pollen from stamens of white flower to carpel of purple flower 3 Pollinated carpel matured into pod 4 Planted seeds from pod
    4. 6. Phenotype - appearance or function of body Genotype - genes that determine the phenotype
    5. 7. <ul><li>P = parental generation </li></ul><ul><li>F 1 = first progeny generation (filial) </li></ul><ul><li>F 2 = second progeny generation </li></ul><ul><li>Monohybrid cross = parents differ in one gene </li></ul>Genetic terms
    6. 8. YY YY YY YY yy yy yy yy Y Y y y Y Y y y Y Y y y Yy Yy Yy Yy Yy Yy Yy Yy female male female gametes male gametes possible outcomes in fertilization P generation
    7. 9. YY yy Yy Yy YY Yy Yy yy yellow green three genotypes two phenotypes Y Y y y F1 generation: F2 generation Punnett square shows parental gametes and genotypes of next generation
    8. 10. 1st law - segregation of alleles <ul><li>Cells contain 2 copies of each gene (alleles) </li></ul><ul><li>Alleles do not blend (dominant, recessive) </li></ul><ul><li>Alleles separate during gamete formation (meiosis) </li></ul>
    9. 11. Yy YY Yy Yy yy “ pure” green F 1 generation F 2 generation self-pollination “ pure” yellow mixed Yy YY Yy yy YY yy Yy YY F 3 generation YY YY YY YY YY Yy Yy yy yy yy yy yy Yy YY Yy yy yy
    10. 12. What happens in dihybrid crosses? - parents differ in genes for 2 traits Monohybrid crosses in Mendel’s peas
    11. 13. Figure 9.5A HYPOTHESIS: DEPENDENT ASSORTMENT HYPOTHESIS: INDEPENDENT ASSORTMENT P GENERATION F 1 GENERATION F 2 GENERATION RRYY rryy Gametes RY Yellow round ry RrYy Eggs Sperm RY ry RY ry 1 / 2 1 / 2 1 / 2 1 / 2 Actual results contradict hypothesis RRYY rryy RY ry Gametes RrYy Eggs RY rY 1 / 4 1 / 4 Ry ry 1 / 4 1 / 4 RY rY Ry ry 1 / 4 1 / 4 1 / 4 1 / 4 RRYY RrYY RrYY RRYy rrYY RrYy RrYy RrYy RrYy RrYy rrYy RRyy rrYy Rryy Rryy rryy 9 / 16 3 / 16 3 / 16 1 / 16 Green round Yellow wrinkled Green wrinkled ACTUAL RESULTS SUPPORT HYPOTHESIS
    12. 14. Law of Independent Assortment <ul><li>During gamete formation, genes for different traits separate independently into gametes </li></ul><ul><li>Why? random alignment of homologues at Meiosis I </li></ul><ul><li>A sperm or egg carries only one allele of each pair </li></ul>
    13. 15. <ul><li>Independent assortment of two genes in the Labrador retriever </li></ul>Figure 9.5B PHENOTYPES Black coat, normal vision B_N_ Blind GENOTYPES MATING OF HETEROZYOTES (black, normal vision) PHENOTYPIC RATIO OF OFFSPRING Black coat, blind (PRA) B_nn Chocolate coat, normal vision bbN_ Chocolate coat, blind (PRA) bbnn 9 black coat, normal vision 3 black coat, blind (PRA) 3 chocolate coat, normal vision 1 chocolate coat, blind (PRA) Blind BbNn BbNn
    14. 16. Figure 9.17 Chromosome behavior accounts for Mendel’s principles
    15. 17. <ul><li>The offspring of a testcross can reveal the genotype of a parent. </li></ul>TESTCROSS: B_ GENOTYPES bb BB Bb or Two possibilities for the black dog: GAMETES OFFSPRING All black 1 black : 1 chocolate B b B b b Bb Bb bb Figure 9.6
    16. 18. <ul><li>Genes on the same chromosome tend to be inherited together = linked genes </li></ul><ul><li>Crossing over produces gametes with recombinant chromosomes </li></ul>A B a b Tetrad Crossing over A B a b a B A b Gametes
    17. 19. <ul><li>Crossing over is more likely to occur between genes that are farther apart </li></ul><ul><ul><li>Recombination frequencies </li></ul></ul>Geneticists use crossover data to map genes g Figure 9.20B Chromosome c l 17% 9% 9.5%
    18. 20. <ul><li>an offspring’s phenotype is intermediate between the phenotypes of its parents </li></ul>Incomplete dominance P GENERATION F 1 GENERATION F 2 GENERATION Red RR Gametes R r White rr Pink Rr R r R R r r 1 / 2 1 / 2 1 / 2 1 / 2 1 / 2 1 / 2 Sperm Eggs Pink Rr Pink rR White rr Red RR Figure 9.12A VARIATIONS ON MENDEL’S PRINCIPLES
    19. 21. <ul><li>Incomplete dominance in human hypercholesterolemia </li></ul>Figure 9.12B GENOTYPES: HH Homozygous for ability to make LDL receptors Hh Heterozygous hh Homozygous for inability to make LDL receptors PHENOTYPES: LDL LDL receptor Cell Normal Mild disease Severe disease
    20. 22. <ul><li>The three alleles for ABO blood type in humans is an example </li></ul>Many genes have more than two alleles in the population
    21. 23. <ul><li>Blood contains genetically determined proteins </li></ul><ul><li>A foreign protein (antigen) may be attacked by the immune system </li></ul>Blood is “typed” by using antibodies that will cause blood with certain proteins to clump (agglutination)
    22. 25. <ul><li>ABO blood types </li></ul>Figure 9.13x
    23. 26. <ul><li>pleiotropy is when a single gene affects phenotype in many ways </li></ul><ul><ul><li>Ex. Marfan syndrome - fibrillin </li></ul></ul><ul><ul><li>The gene’s effects may be dependent on environment, and not be simultaneous. </li></ul></ul><ul><ul><li>Ex. sickle-cell disease - hemoglobin </li></ul></ul>
    24. 27. Individual homozygous for sickle-cell allele Sickle-cell (abnormal) hemoglobin Abnormal hemoglobin crystallizes, causing red blood cells to become sickle-shaped Sickle cells Breakdown of red blood cells Clumping of cells and clogging of small blood vessels Accumulation of sickled cells in spleen Physical weakness Anemia Heart failure Pain and fever Brain damage Damage to other organs Spleen damage Kidney failure Rheumatism Pneumonia and other infections Paralysis Impaired mental function Figure 9.14
    25. 28. <ul><li>This situation creates a continuum of phenotypes </li></ul><ul><li>Quantitative traits </li></ul><ul><ul><li>Example: skin color, height </li></ul></ul>A single characteristic may be influenced by many genes
    26. 29. Figure 9.16 P GENERATION F 1 GENERATION F 2 GENERATION aabbcc (very light) AABBCC (very dark) AaBbCc AaBbCc Eggs Sperm Fraction of population Skin pigmentation
    27. 30. Environmental Effects on Phenotype <ul><li>Genotype and environment can interact to affect phenotype </li></ul><ul><ul><li>Himalayan rabbit ice pack experiment </li></ul></ul><ul><ul><li>Transplantation of plant cuttings to different elevations </li></ul></ul><ul><ul><li>Human depression </li></ul></ul>
    28. 31. <ul><li>All genes on the sex chromosomes are said to be sex-linked </li></ul><ul><ul><li>the X chromosome carries many genes unrelated to sex </li></ul></ul><ul><ul><li>Ex. Fruit fly eye color </li></ul></ul>Sex-linked genes exhibit a unique pattern of inheritance Figure 9.22A
    29. 32. <ul><li>Most sex-linked human disorders are due to recessive alleles </li></ul><ul><ul><li>Ex: hemophilia, red-green color blindness </li></ul></ul><ul><ul><li>mostly in males </li></ul></ul><ul><ul><li>If a male receives a single X-linked recessive allele from his mother, he will have the disorder; while a female has to receive the allele from both parents to be affected </li></ul></ul>Sex-linked disorders affect mostly males Figure 9.23A
    30. 33. <ul><li>A high incidence of hemophilia has plagued the royal families of Europe </li></ul>Figure 9.23B Queen Victoria Albert Alice Louis Alexandra Czar Nicholas II of Russia Alexis
    31. 34. <ul><li>Chromosomes determine sex in many species </li></ul>Figure 9.21B-D <ul><ul><li>The X-O system </li></ul></ul><ul><ul><li>The Z-W system </li></ul></ul><ul><ul><li>Chromosome number </li></ul></ul>
    32. 35. Variations on Mendel’s Principles <ul><li>Codominance, multiple alleles </li></ul><ul><li>Pleiotropy </li></ul><ul><li>Polygenic traits </li></ul><ul><li>Sex-linked genes </li></ul><ul><li>Environmental effects </li></ul>
    33. 36. <ul><li>Karyotyping and biochemical tests of fetal cells and molecules can help people make reproductive decisions </li></ul><ul><ul><li>Fetal cells can be obtained through amniocentesis </li></ul></ul>Connection: Fetal testing can spot many inherited disorders early in pregnancy Figure 9.10A Amniotic fluid Fetus (14-20 weeks) Placenta Amniotic fluid withdrawn Centrifugation Fetal cells Fluid Uterus Cervix Cell culture Several weeks later Karyotyping Biochemical tests
    34. 37. <ul><li>Chorionic villus sampling is another procedure that obtains fetal cells for karyotyping </li></ul>Figure 9.10B Fetus (10-12 weeks) Placenta Chorionic villi Suction Several hours later Fetal cells (from chorionic villi) Karyotyping Some biochemical tests
    35. 38. <ul><li>Examination of the fetus with ultrasound is another helpful technique </li></ul>Figure 9.10C, D
    36. 39. <ul><li>The inheritance of many human traits follows Mendel’s principles and the rules of probability </li></ul>Genetic traits in humans can be tracked through family pedigrees Figure 9.8A
    37. 40. <ul><li>Family pedigrees are used to determine patterns of inheritance and individual genotypes </li></ul>Figure 9.8B Dd Joshua Lambert Dd Abigail Linnell D_ Abigail Lambert Female Dd Elizabeth Eddy D_ John Eddy ? D_ Hepzibah Daggett ? ? dd Dd Dd Dd dd Dd Dd Male Deaf Hearing dd Jonathan Lambert
    38. 41. <ul><li>A few are caused by dominant alleles </li></ul>Figure 9.9B <ul><ul><li>Examples: achondroplasia, Huntington’s disease </li></ul></ul>
    39. 42. Table 9.9
    40. 43. <ul><li>Most such disorders are caused by autosomal recessive alleles </li></ul><ul><ul><li>Examples: cystic fibrosis, sickle-cell disease </li></ul></ul>Connection: Many inherited disorders in humans are controlled by a single gene Figure 9.9A D D d d Normal Dd Normal Dd DD Normal Dd Normal (carrier) Dd Normal (carrier) dd Deaf Eggs Sperm PARENTS OFFSPRING

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