1. Human Genetics

3. Karyotyping: technique for examining the chromosome make up of an organism shows chromosomes arranged by size: – homologous pairs a way of detecting abnormalities chromosomes paired –Total of 46 chromosomes –Or 23 pair  22 autosomes, somatic cells, body cells & –1 pair of sex chromosomes XX = female XX = female XY = male XY = male

4. Chromosome Mapping: Showing the location of particular genes on a chromosome Identifies traits that are likely to “cross over” together the closer the traits the more likely the traits will be inherited together. the closer the traits the more likely the traits will be inherited together.

5. Linkage Groups: each chromosome carries many genes genes on the same chromosome = linked group = linked group linked groups tend to be inherited together crossing over (prophase) can interfere with linkage groups

6. Sex- Linkage: Genes located on the sex chromosomes –genes found on the x chromosome = x linked –genes found on the y chromosome = y linked a gene found on either the x or y chromosomes = sex linked

7. STOP!!! CK POINT!! Topic: Intro to Human Genetics Identify the following: What is/are: 1. Karyotypes 2. Chromosome mapping 3. Sex- linked traits

8. Mutations: any change in the genetic hereditary material of the cell 2 forms: –inheritable mutations – occur in the sex cells Chromosomal mutation Gene mutation –non inheritable mutations – occur in the somatic cells (autosomes, body cells)

9. 2 Types of inheritable mutations: 1. Chromosomal Mutations And 2. Gene mutations

10. Chromosomal Mutations: change in the structure of a chromosome the loss of an entire chromosome or addition of a chromosome –Examples Include: a. Nondisjunction

11. STOP!!! CK POINT!! Topic: Mutations 1 What is a mutation? What are the 2 types of inheritable mutations? Explain how they are different.

12. Chromosome Mutation Cont. A. Nondisjunction: failure of chromosomes to separate during meiosis –ex. Down syndrome – extra chromosome # 21 –ex. Polyploidy – extra whole sets of chromosomes lethal in humans (3n), often used in agriculture to enhance size of plants causes sterility –Ex.trisomy 18, trisomy 13 –EX. aneuploids – missing chromosome Sex chromosome aneuploids :

13. Nondisjunction:

14. Nondisjunction Down syndrome (trisomy 21): Down syndrome Down syndrome The result of an extra copy of chromosome 21. Down syndrome affects 1:700 children and severely alters the child's phenotype: characteristic facial features, short stature; heart defects susceptibility to respiratory disease, shorter lifespan prone to developing early Alzheimer's and leukemia often sexually underdeveloped and sterile

15. Nondisjunction: Patau syndrome (trisomy 13): serious eye, brain, circulatory defects as well as cleft palate. 1:5000 live births. Children rarely live more than a few months.

17. Nondisjunction Edward's syndrome (trisomy 18): almost every organ system affected Children rarely live more than a few months.

19. Other Examples of Nondisjunction: Sex chromosome aneuploids : Sex chromosome aneuploids 1. XO = Turners Syndrome 2. XXY = Klinefelter Syndrome Klinefelter SyndromeKlinefelter Syndrome 3. XXX = Triplo-X Syndrome Triplo-X SyndromeTriplo-X Syndrome 4. XYY =Jacob Syndrome Jacob SyndromeJacob Syndrome

20. Turners Syndrome: XO individuals are genetically female, however, they do not mature sexually during puberty and are sterile. Short stature and normal intelligence. (98% die before birth)

21. XXY = Klinefelter Syndrome Klinefelter SyndromeKlinefelter Syndrome Male sex organs; unusually small testes, sterile. Breast enlargement and other feminine body characteristics. Normal intelligence.

22. XXX = Triplo-X Syndrome Triplo-X SyndromeTriplo-X Syndrome XXX females. 1:1000 live births - healthy and fertile - cannot be distinguished from normal female except by karyotype

23. STOP!!! CK POINT!! Topic: Nondisjunction What is Nondisjunction? When does it occur? ( Be Specific) Identify 3 genetic mutations resulting from nondisjunction. –What is the cause for each?

24. Chromosome mutations (structure): hromosome mutationshromosome mutations translocation – a section of one chromosome is transferred to a nonhomogulous chromosome addition – a portion of a chromosome is added deletion – a portion of a chromosome is deleted Cri-du-Chat Syndrome (segmental deletion) inversion – order of genes on a chromosome is changed

25. Chromosomal mutation- Deletion: Example - Cri du chat (cry of the cat): A deletion of a small portion of chromosome 5; these children have severe mental retardation, a small head with unusual facial features, and a cry that sounds like a distressed cat.

27. Translocation: Some human diseases caused by translocations are: CancerCancer: several forms of cancer are caused by translocations; this has been described mainly in leukemia leukemia Cancerleukemia Infertility

28. In summary Chromosomal Mutations: Chromosomal abnormalities can cause serious mental or physical disabilities, and may lead to the death of the embryo. Structure of the chromosome has been compromised The number of chromosomes is incorrect

29. STOP!!! CK POINT!! Topic: Mutations 2 1. Identify 4 structural chromosomal mutations. 2. How are each of the 4 chromosomes mutated? 3. What is Turners Syndrome?

30. Gene Mutations Point Mutation – the substitution, addition, or removal of a single nucleotide –substitutions, one nucleotide in a codon is replaced with a different nucleotide, resulting in a new codon. sickle cell anemia (also called sickle cell disease) is caused by a point mutation that substitutes Adenine for Thymine in a single DNA codon,

31. Gene Mutations Cont. Frame Shift Mutation -the addition or deletion of a single nucleotide causes the remaining codons to be incorrectly grouped –Addition/removal – a single nucleotide is added or removed –Addition and Deletion Mutations Addition and Deletion MutationsAddition and Deletion Mutations

32. Welcome to Discovery Education Player Welcome to Discovery Education Player

33. Mutagenic Agents: radiation - x-rays, radioactive isotopes, cosmic rays, ultraviolet rays chemicals – saccharin, nitrates, carcinogens

34. Human Genetic Traits & Disorders X- linked Traits: traits controlled by the female sex chromosome symbolized by a character on 1 of the chromosomes –XX’  X’ carries the trait –The female = the carrier –The trait is not visible in the female Ex. Hemophilia –blood disorder in which blood does not clot properly Ex. Color blindness – cannot distinguish between red and green

40. X-linked traits cont. Symbols for constructing a Punnett square (sex-linked trait) XX normal female XY normal male X’X carrier female X’Y male with hemophilia http://www.macmed.ttuhsc.edu/Morgan/ble edingdisorders/pages/newpage26.htm http://www.macmed.ttuhsc.edu/Morgan/ble edingdisorders/pages/newpage26.htm

41. Ex. Hemophilia Hemophiliac male x carrier female GenotypePhenotype

42. Hemophilia contin. Normal male x female carrier GenotypePhenotype

43. Multiple Alleles: 2 or more alleles for a particular trait alleles are expressed as codominant ex. Blood types

44. Human Blood Types: Phenotype Genotype Symbol A AA, AOIaIa, Iai A AA, AOIaIa, Iai B BB, BOIbIb, Ibi B BB, BOIbIb, Ibi AB ABIaIb AB ABIaIb O OOii O OOii

45. Blood Types & Punnett Squares; What are the possible outcomes for a heterozygous A blood type crossing with a homozygous B blood type? GenotypesPhenotypes

46. Blood Type Cont. Construct a punnett square showing a cross b/w a blood type O person with a heterozygous B blood type person GenotypePhenotype

47. Polygenic Traits: traits controlled by 2 or more alleles expressed as incomplete dominance ex. Eye color, height, and skin color

48. Genetic Disorders: Genetic screening or studying karyotyes can show possible genetic disorders –Amniocentesis – karyotyping and analyzing amniotic fluid for fetal cells –Chorionic villisampling – piece of the placenta that is studied for genetic abnormalities –Ex. PKU: a genetic disorder that does not allow the baby to breakdown phenylalanine, can cause severe brain damage Can be detected and eliminated with special diets