Chromosomes andHuman Inheritance    Chapter 12
Impacts, Issues:Strange Genes, Tortured Minds Exceptional creativity often accompanies  neurobiological disorders such as...
12.1 Human Chromosomes In humans, two sex chromosomes are the  basis of sex – human males have XY sex  chromosomes, femal...
Sex Determination in Humans Sex of a child is determined by the father  • Eggs have an X chromosome; sperm have X or Y
Sex Determination in Humans The SRY gene on the Y chromosome is the  master gene for male sex determination  • Triggers f...
Sexual Development in Humans
diploid                                        diploid       germ cells                                     germ cells    ...
Fig. 12-2bc, p. 186
At seven weeks, appearance of              At seven weeks, appearance “uncommitted” duct system of                of struc...
Animation: Human sex determination
Karyotyping Karyotype  • A micrograph of all metaphase chromosomes in a    cell, arranged in pairs by size, shape, and le...
Karyotyping
Fig. 12-3a, p. 187
Fig. 12-3b, p. 187
Animation: Karyotype preparation
12.1 Key ConceptsAutosomes and Sex Chromosomes All animals have pairs of autosomes –  chromosomes that are identical in l...
12.2 Autosomal Inheritance Patterns Many human traits can be traced to autosomal  dominant or recessive alleles that are ...
Autosomal Dominant Inheritance A dominant autosomal allele is expressed in  homozygotes and heterozygotes  • Tends to app...
Autosomal Recessive Inheritance Autosomal recessive alleles are expressed only  in homozygotes; heterozygotes are carrier...
Autosomal Inheritance
Fig. 12-4a, p. 188
Fig. 12-4b, p. 188
Animation: Autosomal dominantinheritance
Animation: Autosomal recessiveinheritance
Galactosemia
Neurobiological Disorders Most neurobiological disorders do not follow  simple patterns of Mendelian inheritance  • Depre...
12.3 Too Young to be Old Progeria  • Genetic disorder that results in accelerated aging  • Caused by spontaneous mutation...
12.2-12.3 Key ConceptsAutosomal Inheritance Many genes on autosomes are expressed in  Mendelian patterns of simple domina...
12.4 Examples of X-Linked Inheritance X chromosome alleles give rise to phenotypes  that reflect Mendelian patterns of in...
X-Linked Inheritance Patterns More males than females have X-linked  recessive genetic disorders  • Males have only one X...
X-Linked Recessive Inheritance Patterns
Animation: X-linked inheritance
Some X-Linked Recessive Disorders Hemophilia A  • Bleeding caused by lack of blood-clotting protein Red-green color blin...
Hemophilia A in Descendentsof Queen Victoria of England
Red-Green Color Blindness
Fig. 12-9a, p. 191
Fig. 12-9b, p. 191
Fig. 12-9c, p. 191
Fig. 12-9d, p. 191
12.4 Key ConceptsSex-Linked Inheritance Some traits are affected by genes on the X  chromosome Inheritance patterns of s...
12.5 Heritable Changesin Chromosome Structure On rare occasions, a chromosome’s structure  changes; such changes are usua...
Duplication DNA sequences are repeated two or more  times; may be caused by unequal crossovers in  prophase I
normalchromosomeone segmentrepeated              p. 192
Deletion Loss of some portion of a chromosome; usually  causes serious or lethal disorders  • Example: Cri-du-chat
segment C deleted                    p. 192
Deletion: Cri-du-chat
Fig. 12-10a, p. 192
Fig. 12-10b, p. 192
Inversion Part of the sequence of DNA becomes oriented  in the reverse direction, with no molecular loss
segmentsG, H, Ibecomeinverted       p. 192
Translocation Typically, two broken chromosomes exchange  parts (reciprocal translocation)
chromosome                           nonhomologous                           chromosomereciprocal translocation           ...
Does Chromosome Structure Evolve? Changes in chromosome structure can reduce  fertility in heterozygotes; but accumulatio...
Differences AmongClosely Related Organisms Humans have 23 pairs  of chromosomes;  chimpanzees, gorillas,  and orangutans ...
human chimpanzee gorilla   orangutan                                       Fig. 12-11, p. 193
Evolution of X and Y Chromosomesfrom Homologous Autosomes
Ancestral reptiles Ancestral reptiles       Monotremes                Marsupials    Monkeys       Humans (autosome pair)  ...
12.6 Heritable Changes inthe Chromosome Number Occasionally, new individuals end up with the  wrong chromosome number  • ...
Nondisjunction Changes in chromosome number can be caused  by nondisjunction, when a pair of  chromosomes fails to separa...
Nondisjunction
Autosomal Change and Down Syndrome Only trisomy 21 (Down syndrome) allows  survival to adulthood  • Characteristics inclu...
Trisomy 21
n+1                                                                   n+1                                                 ...
n+1                                                                   n+1                                                 ...
Down Syndrome and Maternal Age
Fig. 12-14a, p. 195
Fig. 12-14b, p. 195
Change in Sex Chromosome Number Changes in sex chromosome number may  impair learning or motor skills, or be undetected ...
Turner Syndrome XO (one unpaired X  chromosome)  • Usually caused by    nondisjunction in the    father  • Results in fem...
12.5-12.6 Key Concepts: Changes inChromosome Structure or Number On rare occasions, a chromosome may undergo  a large-sca...
12.7 Human Genetic Analysis Charting genetic connections with pedigrees  reveals inheritance patterns for certain alleles...
Studying Inheritance in Humans Genetic studies can  reveal inheritance  patterns or clues to  past events  • Example: A l...
Defining Genetic Disordersand Abnormalities Genetic abnormality  • A rare or uncommon version of a trait; not    inherent...
Some Human Genetic Disordersand Genetic Abnormalities
Stepped ArtTable 12-1, p. 196
Recurring Genetic Disorders Mutations that cause genetic disorders are rare  and put their bearers at risk Such mutation...
A Pedigree for Huntington’s Disease A progressive degeneration of the nervous  system caused by an autosomal dominant all...
Constructing a Pedigree for Polydactyly
Animation: Pedigree diagrams
12.8 Prospects in Human Genetics Genetic analysis can provide parents with  information about their future children Gene...
Prenatal Diagnosis Tests done on an embryo or fetus before birth to  screen for sex or genetic problems  • Involves risks...
Amniocentesis
Animation: Amniocentesis
Fetoscopy
Preimplantation Diagnosis Used in in-vitro fertilization   • An undifferentiated cell is removed from the early     embry...
After Preimplantation Diagnosis When a severe problem is diagnosed, some  parents choose an induced abortion In some cas...
Genetic Screening Genetic screening (widespread, routine testing  for alleles associated with genetic disorders)  •   Pro...
12.7-12.8 Key ConceptsHuman Genetic Analysis Various analytical and diagnostic procedures  often reveal genetic disorders...
Animation: Deletion
Animation: Duplication
Animation: Inversion
Animation: Morgan’s reciprocal crosses
Animation: Translocation
Video: Strange genes, richly torturedminds
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GENETICS

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  • Figure 12.2 ( a ) Punnett-square diagram showing the sex determination pattern in humans. ( b ) An early human embryo appears neither male nor female. Then tiny ducts and other structures that can develop into male or female reproductive organs start forming. In an XX embryo, ovaries form in the absence of the Y chromosome and its SRY gene. In an XY embryo, the gene product triggers formation of testes, which secrete a hormone that initiates development of other male traits. ( c ) External reproductive organs in human embryos.
  • Figure 12.2 ( a ) Punnett-square diagram showing the sex determination pattern in humans. ( b ) An early human embryo appears neither male nor female. Then tiny ducts and other structures that can develop into male or female reproductive organs start forming. In an XX embryo, ovaries form in the absence of the Y chromosome and its SRY gene. In an XY embryo, the gene product triggers formation of testes, which secrete a hormone that initiates development of other male traits. ( c ) External reproductive organs in human embryos.
  • Figure 12.2 ( a ) Punnett-square diagram showing the sex determination pattern in humans. ( b ) An early human embryo appears neither male nor female. Then tiny ducts and other structures that can develop into male or female reproductive organs start forming. In an XX embryo, ovaries form in the absence of the Y chromosome and its SRY gene. In an XY embryo, the gene product triggers formation of testes, which secrete a hormone that initiates development of other male traits. ( c ) External reproductive organs in human embryos.
  • Figure 12.3 Karyotyping, a diagnostic tool that reveals an image of a single cell’s diploid complement of chromosomes. This human karyotype shows 22 pairs of autosomes and a pair of X chromosomes. Figure It Out: Was this cell taken from a male or female? Answer: Female
  • Figure 12.3 Karyotyping, a diagnostic tool that reveals an image of a single cell’s diploid complement of chromosomes. This human karyotype shows 22 pairs of autosomes and a pair of X chromosomes. Figure It Out: Was this cell taken from a male or female? Answer: Female
  • Figure 12.4 ( a ) Example of autosomal dominant inheritance. A dominant allele ( red ) is fully expressed in heterozygotes. Achondroplasia, an autosomal dominant disorder, affects the three men shown above. At center, Verne Troyer (Mini Me in the Mike Myers spy movies), stands two feet, eight inches tall. ( b ) An autosomal recessive pattern. In this example, both parents are heterozygous carriers of the recessive allele ( red ).
  • Figure 12.4 ( a ) Example of autosomal dominant inheritance. A dominant allele ( red ) is fully expressed in heterozygotes. Achondroplasia, an autosomal dominant disorder, affects the three men shown above. At center, Verne Troyer (Mini Me in the Mike Myers spy movies), stands two feet, eight inches tall. ( b ) An autosomal recessive pattern. In this example, both parents are heterozygous carriers of the recessive allele ( red ).
  • Figure 12.9 Left, what red–green color blindness means, using ripe red cherries on a green-leafed tree as an example. In this case, the perception of blues and yellows is normal, but the affected individual has difficulty distinguishing red from green. Right , two of many Ishihara plates, which are standardized tests for different forms of color blindness. ( a ) You may have one form of red–green color blindness if you see the numeral 7 instead of 29 in this circle. ( b ) You may have another form if you see a 3 instead of an 8.
  • Figure 12.9 Left, what red–green color blindness means, using ripe red cherries on a green-leafed tree as an example. In this case, the perception of blues and yellows is normal, but the affected individual has difficulty distinguishing red from green. Right , two of many Ishihara plates, which are standardized tests for different forms of color blindness. ( a ) You may have one form of red–green color blindness if you see the numeral 7 instead of 29 in this circle. ( b ) You may have another form if you see a 3 instead of an 8.
  • Figure 12.9 Left, what red–green color blindness means, using ripe red cherries on a green-leafed tree as an example. In this case, the perception of blues and yellows is normal, but the affected individual has difficulty distinguishing red from green. Right , two of many Ishihara plates, which are standardized tests for different forms of color blindness. ( a ) You may have one form of red–green color blindness if you see the numeral 7 instead of 29 in this circle. ( b ) You may have another form if you see a 3 instead of an 8.
  • Figure 12.9 Left, what red–green color blindness means, using ripe red cherries on a green-leafed tree as an example. In this case, the perception of blues and yellows is normal, but the affected individual has difficulty distinguishing red from green. Right , two of many Ishihara plates, which are standardized tests for different forms of color blindness. ( a ) You may have one form of red–green color blindness if you see the numeral 7 instead of 29 in this circle. ( b ) You may have another form if you see a 3 instead of an 8.
  • Figure 12.10 Cri-du - chat syndrome. ( a ) This infant’s ears are low relative to his eyes. ( b ) Same boy, four years later. The high-pitched monotone of cri-du-chat children may persist into their adulthood.
  • Figure 12.10 Cri-du - chat syndrome. ( a ) This infant’s ears are low relative to his eyes. ( b ) Same boy, four years later. The high-pitched monotone of cri-du-chat children may persist into their adulthood.
  • Figure 12.11 Banding patterns of human chromosome 2 ( a ), compared with two chimpanzee chromosomes ( b ). Bands appear because different regions of the chromosomes take up stain differently.
  • Figure 12.12 Evolution of the Y chromosome. Mya stands for million years ago.
  • Figure 12.13 ( a ) A case of nondisjunction. This karyotype reveals the trisomic 21 condition of a human female. ( b ) One example of how nondisjunction arises. Of the two pairs of homologous chromosomes shown here, one fails to separate during anaphase I of meiosis. The chromosome number is altered in the gametes that form after meiosis.
  • Figure 12.13 ( a ) A case of nondisjunction. This karyotype reveals the trisomic 21 condition of a human female. ( b ) One example of how nondisjunction arises. Of the two pairs of homologous chromosomes shown here, one fails to separate during anaphase I of meiosis. The chromosome number is altered in the gametes that form after meiosis.
  • Figure 12.14 Relationship between the frequency of Down syndrome and mother’s age at childbirth. The data are from a study of 1,119 affected children. The risk of having a trisomic 21 baby rises with the mother’s age. About 80 percent of trisomic 21 individuals are born to women under thirty-five, but these women have the highest fertility rates, and they have more babies.
  • Figure 12.14 Relationship between the frequency of Down syndrome and mother’s age at childbirth. The data are from a study of 1,119 affected children. The risk of having a trisomic 21 baby rises with the mother’s age. About 80 percent of trisomic 21 individuals are born to women under thirty-five, but these women have the highest fertility rates, and they have more babies.
  • GENETICS

    1. 1. Chromosomes andHuman Inheritance Chapter 12
    2. 2. Impacts, Issues:Strange Genes, Tortured Minds Exceptional creativity often accompanies neurobiological disorders such as schizophrenia, autism, chronic depression, and bipolar disorder • Examples: Lincoln, Woolf, and Picasso
    3. 3. 12.1 Human Chromosomes In humans, two sex chromosomes are the basis of sex – human males have XY sex chromosomes, females have XX All other human chromosomes are autosomes – chromosomes that are the same in males and females
    4. 4. Sex Determination in Humans Sex of a child is determined by the father • Eggs have an X chromosome; sperm have X or Y
    5. 5. Sex Determination in Humans The SRY gene on the Y chromosome is the master gene for male sex determination • Triggers formation of testes, which produce the male sex hormone (testosterone) • Without testosterone, ovaries develop and produce female sex hormones (estrogens)
    6. 6. Sexual Development in Humans
    7. 7. diploid diploid germ cells germ cells in female in malemeiosis, gameteformation in both eggs spermfemale and male: X × Y X × Xfertilization: X X X XX XX Y XY XY sex chromosome combinations possible in the new individual Fig. 12-2a, p. 186
    8. 8. Fig. 12-2bc, p. 186
    9. 9. At seven weeks, appearance of At seven weeks, appearance “uncommitted” duct system of of structures that will give embryo rise to external genitaliaY chromosome Y chromosome Y chromosome Y chromosome present absent present absent testes ovaries 10 weeks 10 weeks ovary penis vaginal opening uterus penis vagina testis birth approaching b c Fig. 12-2bc, p. 186
    10. 10. Animation: Human sex determination
    11. 11. Karyotyping Karyotype • A micrograph of all metaphase chromosomes in a cell, arranged in pairs by size, shape, and length • Detects abnormal chromosome numbers and some structural abnormalities Construction of a karyotype • Colchicine stops dividing cells at metaphase • Chromosomes are separated, stained, photographed, and digitally rearranged
    12. 12. Karyotyping
    13. 13. Fig. 12-3a, p. 187
    14. 14. Fig. 12-3b, p. 187
    15. 15. Animation: Karyotype preparation
    16. 16. 12.1 Key ConceptsAutosomes and Sex Chromosomes All animals have pairs of autosomes – chromosomes that are identical in length, shape, and which genes they carry Sexually reproducing species also have a pair of sex chromosomes; the members of this pair differ between males and females
    17. 17. 12.2 Autosomal Inheritance Patterns Many human traits can be traced to autosomal dominant or recessive alleles that are inherited in Mendelian patterns Some of those alleles cause genetic disorders
    18. 18. Autosomal Dominant Inheritance A dominant autosomal allele is expressed in homozygotes and heterozygotes • Tends to appear in every generation • With one homozygous recessive and one heterozygous parent, children have a 50% chance of inheriting and displaying the trait • Examples: achondroplasia, Huntington’s disease
    19. 19. Autosomal Recessive Inheritance Autosomal recessive alleles are expressed only in homozygotes; heterozygotes are carriers and do not have the trait • A child of two carriers has a 25% chance of expressing the trait • Example: galactosemia
    20. 20. Autosomal Inheritance
    21. 21. Fig. 12-4a, p. 188
    22. 22. Fig. 12-4b, p. 188
    23. 23. Animation: Autosomal dominantinheritance
    24. 24. Animation: Autosomal recessiveinheritance
    25. 25. Galactosemia
    26. 26. Neurobiological Disorders Most neurobiological disorders do not follow simple patterns of Mendelian inheritance • Depression, schizophrenia, bipolar disorders Multiple genes and environmental factors contribute to NBDs
    27. 27. 12.3 Too Young to be Old Progeria • Genetic disorder that results in accelerated aging • Caused by spontaneous mutations in autosomes
    28. 28. 12.2-12.3 Key ConceptsAutosomal Inheritance Many genes on autosomes are expressed in Mendelian patterns of simple dominance Some dominant or recessive alleles result in genetic disorders
    29. 29. 12.4 Examples of X-Linked Inheritance X chromosome alleles give rise to phenotypes that reflect Mendelian patterns of inheritance Mutated alleles on the X chromosome cause or contribute to over 300 genetic disorders
    30. 30. X-Linked Inheritance Patterns More males than females have X-linked recessive genetic disorders • Males have only one X chromosome and can express a single recessive allele • A female heterozygote has two X chromosomes and may not show symptoms Males transmit an X only to their daughters, not to their sons
    31. 31. X-Linked Recessive Inheritance Patterns
    32. 32. Animation: X-linked inheritance
    33. 33. Some X-Linked Recessive Disorders Hemophilia A • Bleeding caused by lack of blood-clotting protein Red-green color blindness • Inability to distinguish certain colors caused by altered photoreceptors in the eyes Duchenne muscular dystrophy • Degeneration of muscles caused by lack of the structural protein dystrophin
    34. 34. Hemophilia A in Descendentsof Queen Victoria of England
    35. 35. Red-Green Color Blindness
    36. 36. Fig. 12-9a, p. 191
    37. 37. Fig. 12-9b, p. 191
    38. 38. Fig. 12-9c, p. 191
    39. 39. Fig. 12-9d, p. 191
    40. 40. 12.4 Key ConceptsSex-Linked Inheritance Some traits are affected by genes on the X chromosome Inheritance patterns of such traits differ in males and females
    41. 41. 12.5 Heritable Changesin Chromosome Structure On rare occasions, a chromosome’s structure changes; such changes are usually harmful or lethal, rarely neutral or beneficial A segment of a chromosome may be duplicated, deleted, inverted, or translocated
    42. 42. Duplication DNA sequences are repeated two or more times; may be caused by unequal crossovers in prophase I
    43. 43. normalchromosomeone segmentrepeated p. 192
    44. 44. Deletion Loss of some portion of a chromosome; usually causes serious or lethal disorders • Example: Cri-du-chat
    45. 45. segment C deleted p. 192
    46. 46. Deletion: Cri-du-chat
    47. 47. Fig. 12-10a, p. 192
    48. 48. Fig. 12-10b, p. 192
    49. 49. Inversion Part of the sequence of DNA becomes oriented in the reverse direction, with no molecular loss
    50. 50. segmentsG, H, Ibecomeinverted p. 192
    51. 51. Translocation Typically, two broken chromosomes exchange parts (reciprocal translocation)
    52. 52. chromosome nonhomologous chromosomereciprocal translocation p. 192
    53. 53. Does Chromosome Structure Evolve? Changes in chromosome structure can reduce fertility in heterozygotes; but accumulation of multiple changes in homozygotes may result in new species Certain duplications may allow one copy of a gene to mutate while the other carries out its original function
    54. 54. Differences AmongClosely Related Organisms Humans have 23 pairs of chromosomes; chimpanzees, gorillas, and orangutans have 24 • Two chromosomes fused end-to-end
    55. 55. human chimpanzee gorilla orangutan Fig. 12-11, p. 193
    56. 56. Evolution of X and Y Chromosomesfrom Homologous Autosomes
    57. 57. Ancestral reptiles Ancestral reptiles Monotremes Marsupials Monkeys Humans (autosome pair) Y X Y X Y X Y X Y X areas that can cross over areas that SRY cannot cross overA Before 350 B SRY gene C By 320–240 mya, the D Three more times, 170–130 mya,mya, sex was evolves 350 mya. two chromosomes have the pair stops crossing over indetermined by Other mutations diverged so much that another region. Each time, moretemperature, not accumulate and they no longer cross changes accumulate, and the Yby chromosome the chromosomes over in one region. The chromosome gets shorter. Today, tdifferences. of the pair diverge. Y chromosome begins he pair crosses over only at a small to degenerate. region near the ends. Fig. 12-12, p. 193
    58. 58. 12.6 Heritable Changes inthe Chromosome Number Occasionally, new individuals end up with the wrong chromosome number • Consequences range from minor to lethal Aneuploidy • Too many or too few copies of one chromosome Polyploidy • Three or more copies of each chromosome
    59. 59. Nondisjunction Changes in chromosome number can be caused by nondisjunction, when a pair of chromosomes fails to separate properly during mitosis or meiosis Affects the chromosome number at fertilization • Monosomy (n-1 gamete) • Trisomy (n+1 gamete)
    60. 60. Nondisjunction
    61. 61. Autosomal Change and Down Syndrome Only trisomy 21 (Down syndrome) allows survival to adulthood • Characteristics include physical appearance, mental impairment, and heart defects Incidence of nondisjunction increases with maternal age Can be detected through prenatal diagnosis
    62. 62. Trisomy 21
    63. 63. n+1 n+1 n−1 n−1chromosome CHROMOSOMEalignments at NONDISJUNCTION alignments at NUMBER metaphase I AT ANAPHASE I metaphase II anaphase II IN GAMETES Fig. 12-13b, p. 194
    64. 64. n+1 n+1 n−1 n−1chromosome CHROMOSOMEalignments at NONDISJUNCTION alignments at NUMBER metaphase I AT ANAPHASE I metaphase II anaphase II IN GAMETES Stepped Art Fig. 12-13b, p. 194
    65. 65. Down Syndrome and Maternal Age
    66. 66. Fig. 12-14a, p. 195
    67. 67. Fig. 12-14b, p. 195
    68. 68. Change in Sex Chromosome Number Changes in sex chromosome number may impair learning or motor skills, or be undetected Female sex chromosome abnormalities • Turner syndrome (XO) • XXX syndrome (three or more X chromosomes) Male sex chromosome abnormalities • Klinefelter syndrome (XXY) • XYY syndrome
    69. 69. Turner Syndrome XO (one unpaired X chromosome) • Usually caused by nondisjunction in the father • Results in females with undeveloped ovaries
    70. 70. 12.5-12.6 Key Concepts: Changes inChromosome Structure or Number On rare occasions, a chromosome may undergo a large-scale, permanent change in its structure, or the number of autosomes or sex chromosomes may change In humans, such changes usually result in a genetic disorder
    71. 71. 12.7 Human Genetic Analysis Charting genetic connections with pedigrees reveals inheritance patterns for certain alleles Pedigree • A standardized chart of genetic connections • Used to determine the probability that future offspring will be affected by a genetic abnormality or disorder
    72. 72. Studying Inheritance in Humans Genetic studies can reveal inheritance patterns or clues to past events • Example: A link between a Y chromosome and Genghis Khan?
    73. 73. Defining Genetic Disordersand Abnormalities Genetic abnormality • A rare or uncommon version of a trait; not inherently life threatening Genetic disorder • An inherited condition that causes mild to severe medical problems, characterized by a specific set of symptoms (a syndrome)
    74. 74. Some Human Genetic Disordersand Genetic Abnormalities
    75. 75. Stepped ArtTable 12-1, p. 196
    76. 76. Recurring Genetic Disorders Mutations that cause genetic disorders are rare and put their bearers at risk Such mutations survive in populations for several reasons • Reintroduction by new mutations • Recessive alleles are masked in heterozygotes • Heterozygotes may have an advantage in a specific environment
    77. 77. A Pedigree for Huntington’s Disease A progressive degeneration of the nervous system caused by an autosomal dominant allele
    78. 78. Constructing a Pedigree for Polydactyly
    79. 79. Animation: Pedigree diagrams
    80. 80. 12.8 Prospects in Human Genetics Genetic analysis can provide parents with information about their future children Genetic counseling • Starts with parental genotypes, pedigrees, and genetic testing for known disorders • Information is used to predict the probability of having a child with a genetic disorder
    81. 81. Prenatal Diagnosis Tests done on an embryo or fetus before birth to screen for sex or genetic problems • Involves risks to mother and fetus Three types of prenatal diagnosis • Amniocentesis • Chorionic villus sampling (CVS) • Fetoscopy
    82. 82. Amniocentesis
    83. 83. Animation: Amniocentesis
    84. 84. Fetoscopy
    85. 85. Preimplantation Diagnosis Used in in-vitro fertilization • An undifferentiated cell is removed from the early embryo and examined before implantation
    86. 86. After Preimplantation Diagnosis When a severe problem is diagnosed, some parents choose an induced abortion In some cases, surgery, prescription drugs, hormone replacement therapy, or dietary controls can minimize or eliminate symptoms of a genetic disorder • Example: PKU can be managed with dietary restrictions
    87. 87. Genetic Screening Genetic screening (widespread, routine testing for alleles associated with genetic disorders) • Provides information on reproductive risks • Identifies family members with a genetic disorder • Used to screen newborns for certain disorders • Used to estimate the prevalence of harmful alleles in a population
    88. 88. 12.7-12.8 Key ConceptsHuman Genetic Analysis Various analytical and diagnostic procedures often reveal genetic disorders What an individual, and society at large, should do with the information raises ethical questions
    89. 89. Animation: Deletion
    90. 90. Animation: Duplication
    91. 91. Animation: Inversion
    92. 92. Animation: Morgan’s reciprocal crosses
    93. 93. Animation: Translocation
    94. 94. Video: Strange genes, richly torturedminds

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