1. Human Inheritance
Do you think humans are the ideal subjects to be used to study genetics? Why or why not?

2. Fruit Fly Ideal organism used to study genetics
Suggested by Thomas Hunt Morgan
Fruit Fly

3. Advantages For Studying Genetics In the Fruit Fly
1.Short Generation Time: They can reproduce a new generation in just a few weeks
2. Small in Size: small & easy to maintain in large # in a lab setting
3. Simple Genetic System :2n=8
Advantages For Studying Genetics In the Fruit Fly
-2 Aunts on both moms and dads side.
-Sister goes to River ridge

4. Total of 23 homologous pair of chromosomes.
( A total of 46)
Human Chromosomes
2n = 46
n= 23
Kindergarten: learning basic math and reading skills
1st:don’t remember reading changing.
4th: Science was pretty simple when it started

5. Different organism have different chromosome numbers

6. Genome
To find what makes us uniquely human, we have to explore the human genome.
A genome is the full set of genetic information that an organism carries in its DNA.
A study of any genome starts with chromosomes, the bundles of DNA and protein found in the nuclei of eukaryotic cells.

7. Scientists cut out chromosomes from a photograph and arrange them in a picture known as a karyotype.
A karyotype shows the complete diploid set of chromosomes grouped together in pairs, arranged in order of decreasing size.
A karyotype from a typical human cell, which contains 46 chromosomes, is arranged in 23 pairs.

8. X & Y chromosomes that determine the sex of the individual
Sex Chromosomes
Female XX
Male: XY

9. All human egg cells carry a single X chromosome (23,X).
However, half of all sperm cells carry an X chromosome (23,X) and half carry a Y chromosome (23,Y).
This ensures that just about half the zygotes will be males and half will be females.

11. Sex Chromosomes
More than 1200 genes are found on the X chromosome, some of which are shown.
The human Y chromosome is much smaller than the X chromosome and contains only about 140 genes, most of which are associated with male sex determination and sperm development.

12. Autosomes Autosomal Chromosomes
Any chromosome other than a sex chromosome
Humans have 22 homologous pair of autosomes

13. The complete human genome consists of 46 chromosomes, including 44 autosomes and 2 sex chromosomes.
To quickly summarize the total number of chromosomes present in a human cell, biologists write 46,XX for females and 46,XY for males.

17. Pedigrees
To analyze the pattern of inheritance followed by a particular trait, you can use a chart, called a pedigree, which shows the relationships within a family.
A pedigree shows the presence or absence of a trait according to the relationships between parents, siblings, and offspring.

18. A pedigree is a diagram that follows the inheritance of a single gene through several generations in a family.
The information gained from pedigree analysis makes it possible to determine the nature of genes and alleles associated with inherited human traits. Based on a pedigree, you can often determine if an allele for a trait is dominant or recessive, autosomal or sex-linked.

19. Symbols
Females
(Circles)
Males
(Squares)

20. Individuals showing the trait (homozygous dominant or recessive): shaded circle or square
Heterozygous: ½ shaded circle or square; carrier of the recessive trait
Vertical line—connects parents & their children
Horizontal line—connects male & female parents

21. A recessive trait / disorder

22. Human Pedigrees
This pedigree shows how one human trait—a white lock of hair just above the forehead—passes through three generations of a family. The allele for the white forelock trait is dominant.

23. At the top of the chart is a grandfather who had the white forelock trait.
Two of his three children inherited the trait.
Three grandchildren have the trait, but two do not.

24. Because the white forelock trait is dominant, all the family members in the pedigree lacking this trait must have homozygous recessive alleles.
One of the grandfather’s children lacks the white forelock trait, so the grandfather must be heterozygous for this trait.

25. Jamie who has blonde hair, a recessive trait, marries Jessica, who has brown hair. They have 4 brown-haired children: John, Jennifer, Jackie, and Justin. Justin marries a brown-haired girl named Anna and they have 4 children: Albert, Amanda, Kenny, and Kerri. Kerri has blonde hair. Draw this family’s pedigree

26. Nondisjunction and Autosomal Disorders

27. Humans have 22 pairs of autosomal chromosomes and 1 pair of sex chromosomes

28. Remember:
Females-XX
Males-XY

29. Nondisjunction

30. Chromosomal Disorders
The most common error in meiosis occurs when homologous chromosomes fail to separate. This mistake is known as nondisjunction, which means “not coming apart.”
Nondisjunction may result in gametes with an abnormal number of chromosomes, which can lead to a disorder of chromosome numbers.

31. Chromosomal Disorders
If two copies of an autosomal chromosome fail to separate during meiosis, an individual may be born with three copies of that chromosome.
This condition is known as a trisomy, meaning “three bodies.”
Monosomy – 1 copy only; a shortage

32. Trisomy 21
The most common form of trisomy is known as Down syndrome. There is an extra copy of chromosome 21 (3 copies). This extra chromosome only occurs on the 21stautosome pair.

33. Chromosomal Disorders
Nondisjunction of the X chromosomes can lead to a disorder known as Turner’s syndrome.
A female with Turner’s syndrome usually inherits only one X chromosome.
Women with Turner’s syndrome are sterile, which means that they are unable to reproduce. Their sex organs do not develop properly.
The chromosome arrangement is 45X or 45XO instead of 46XX as in a normal female.

35. Chromosomal Disorders
In males, nondisjunction may cause Klinefelter’s syndrome, resulting from the inheritance of an extra X chromosome, which interferes with meiosis and usually prevents these individuals from reproducing.
There have been no reported instances of babies being born without an X chromosome, indicating that this chromosome contains genes that are vital for the survival and development of the embryo.

36. With karyotype47XXY, this person will appear male, but he is sterile
With karyotype47XXY, this person will appear male, but he is sterile. A normal male is 46XY.

37. Autosomal Disorders

38. Before genetic testing or complete understanding of DNA, observers noticed that genetic traits were passed from one generation to another in predictable patterns.

39. Autosomal Disorders
The genetic mutation is on an autosome, one of the chromosomes that are not an X or Y.

40. Autosomal dominant
– only need one copy of abnormal gene to inherit disease
Ex> Huntington’s Disease-progressive brain disorder; uncontrolled movements, emotional problems, and loss of cognition

41. Huntington’s Disease
Cause- The codon CAG—coding for the amino acid glutamine—repeats over and over again, more than 40 times.
The greater the number of codon repeats, the earlier the disease appears, and the more severe are its symptoms.

42. 2. Neurofibromatosis
Tumors grow on nerve tissue and produce skin and bone abnormalities

43. 3. Dwarfism
A person of short stature as an adult with arms and legs short in comparison to trunk and head

44. Autosomal recessive
– need two copies of abnormal gene to inherit disease

45. 1.Tay-Sachs
Developmental retardation, paralysis, dementia, blindness, retinal “cherry-red” spot;
common among Jewish & French Canadian ancestry.

46. 2. Albinism Little or no melanin, a pigment in eyes, skin or hair
If both parents have albinism, child will not necessarily inherit it; still a mystery

47. 3. PKU (Phenylketonuria)
Inability of body to utilize amino acid phenylalanine
Must limit protein in diet
Left untreated, causes brain development problems, progressive mental retardation, and seizures

48. 4. Cystic Fibrosis
Cystic fibrosis (CF) is most common among people of European ancestry.
Mucus is usually watery; keeps the linings of certain organs moist and prevents them from drying out or getting infected
In CF the abnormal gene causes mucus to become thick & sticky ; blocks the airways
One of the most common fatal genetic disorders

49. Cystic Fibrosis
Cause- deletion of three bases in a gene for a protein called CFTR, removing phenylalanine, causing the protein to fold improperly.
CFTR allows chloride ions (Cl−) to pass across cell membranes

50. Cystic Fibrosis
With cell membranes unable to transport chloride ions, tissues throughout the body malfunction.

51. Genetic Advantages
In the United States, the sickle cell allele is carried by approximately 1 person in 12 of African ancestry, and the CF allele is carried by roughly 1 person in 25 of European ancestry.

52. Genetic Advantages
Most African Americans today are descended from west central Africa, where malaria is common.
Malaria is a mosquito-borne infection caused by a parasite that lives inside red blood cells.

53. Genetic Advantages
Individuals with one copy of the sickle cell allele are healthy and highly resistant to the parasite, a great advantage against malaria.

54. Genetic Advantages
More than 1000 years ago, Europe was ravaged by typhoid fever, caused by a bacterium that enters the body through cells in the digestive system. The protein produced by the CF allele blocks entry of this bacterium.
Individuals carrying one recessive allele would have this advantage when living in cities with poor sanitation and polluted water, and—because they also carried a normal allele,would not have cystic fibrosis.

55. Individuals heterozygous for some diseases have a genetic advantage- one allele resists a dangerous genetic condition and the other allele helps them avoid conditions like plague and malaria.

56. Sex-Linked Traits

57. Sex Chromosomes
Females XX
Males XY

58. The genes located on the X and Y chromosomes show a pattern of inheritance called sex-linked.
A sex-linked gene is a gene located on a sex chromosome.
Genes on the Y chromosome are found only in males and are passed directly from father to son.
Genes located on the X chromosome are found in both sexes, but the fact that men have just one X chromosome leads to some interesting consequences.
In humans the X-chromosome is much larger than the Y chromosome and contains thousands of genes more than the Y chromosome.

59. A normal male inherits an X chromosome from the mother and a Y chromosome from the father. Therefore, normal males inherit sex-linked traits only from their mothers.

60. For each of the genes that are exclusively on the X chromosome:
females, who are XX, would obviously have two alleles
Males, who are XY, would have only one allele.
Therefore, females with one recessive allele and one dominant allele for a gene that is unique to the X chromosome will display the dominant phenotype.
A male with a recessive allele for a gene unique to the X chromosome will always exhibit that recessive trait because there is no other corresponding allele on the Y chromosome.

61. Duchenne Muscular Dystrophy
Sex-Linked Disorders
Colorblindness
Hemophilia
Duchenne Muscular Dystrophy

62. Colorblindness
Humans have three genes responsible for color vision, all located on the X chromosome.
In males, a defective allele for any of these genes results in colorblindness, an inability to distinguish certain colors. The most common form, red-green colorblindness, occurs in about 1 in 12 males.
Among females, however, colorblindness affects only about 1 in 200 because it must be present in two copies—one on each of the X chromosomes.
The recessive phenotype of a sex-linked genetic disorder tends to be much more common among males than among females.

63. Colorblindness
Prevents humans from distinguishing between different colors

64. Hemophilia A disorder affecting human blood clotting
Defective allele prevents the synthesis of a factor needed for blood clotting

65. Duchenne Muscular Dystrophy
Condition in which muscles begin to degenerate in childhood

66. XHXH Chromosome with 2 dominant alleles female Non-hemophilia
Normal type—wild type

67. XhXh
Chromosome with two recessive alleles
female
hemophilia

68. XHXh Chromosome with heterozygous alleles –female carrier
Non-hemophilia

69. XHY Chromosome with one dominant allele male Non-hemophilia
Wild type (normal)

70. XhY
Chromosome with recessive hemophilia allele
Male
hemophilia

71. SAMPLE PROBLEM #1 A man with hemophilia marries a homozygous normal woman. Predict the genotypes and phenotypes of their children.

72. Sample Problem #2 A normal man marries a woman who is a carrier for hemophilia. Predict the genotypes and phenotypes of their children.

73. Human Blood Groups

74. ABO Blood Groups
Determined by a multiple allele system

75. Antigen
molecules which can be recognized by the body’s immune system on the surface of the red blood cell

76. Antibody
molecules in the human body which fights foreign objects that do not agree or mix with the body

77. Some blood types are seen as foreign bodies in the blood of other humans
The antibodies will actually destroy the red blood cells like they are diseases.

78. If a person with type A blood (which has B antibodies) receives blood from a person with type B blood (which has A antibodies) the antibodies will attack the blood, and the person blood may begin to clump or agglutinate.

79. Blood type A & B are codominant
Blood Type O is recessive

81. Blood Types & Genotypes
Type A Blood
IAIA or IAi
Type B Blood
IBIB or IBi
Type AB Blood
IAIB
Type O Blood ii

82. B A, O B, O A & B None A, B, AB, O Blood Group Antigen Antibody
Safe Transfusion From A B
A, O
B, O AB
A & B
None
A, B, AB, O O

83. Rh Factor
Protein substance present in the red blood cells of most people, capable of producing intense antigenic reactions

84. Under ordinary circumstances the presence or lack of the Rh factor has no bearing on life or death

85. It is only when the 2 blood types are mixed in an Rh-negative individual that the difficulty arises; the Rh factor acts as an antigen in the Rh-negative person, causing the production of antibodies