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Human Genetics

Human Genetics. Genetic Experiment 626. Karyotyping:. technique for examining the chromosome make up of an organism shows chromosomes arranged by size : homogulous pairs a way of detecting abnormalities. Karyotyping:. chromosomes paired Total of 46 chromosomes Or 23 pair:

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Human Genetics

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  1. Human Genetics Genetic Experiment 626

  2. Karyotyping: • technique for examining the chromosome make up of an organism • shows chromosomes arranged by size: • homogulous pairs • a way of detecting abnormalities

  3. Karyotyping: • chromosomes paired • Total of 46 chromosomes • Or 23 pair: • 22 autosomes, somatic cells, body cells & • 1 pair of sex chromosomes XX = female XY = male

  4. 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

  5. STOP!!! CK POINT!! Topic: Intro to Human Genetics Identify the following: What is/are: • Karyotypes • Sex- linked traits

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

  7. 2 Types of inheritable mutations: ADD TO YOUR NOTES!! • Chromosomal Mutations And 2. Gene mutations

  8. STOP!!! CK POINT!! Topic: Mutations 1 • What is a mutation? • What are the 2 types of inheritable mutations?

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

  10. Chromosome Mutation Cont. A.Nondisjunction: • failure of chromosomes to separate during meiosis • ex. Down syndrome – extra chromosome # 21 • Ex .trisomy 18, trisomy 13

  11. Nondisjunction:

  12. NondisjunctionDown syndrome(trisomy 21):

  13. 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.

  14. NondisjunctionEdward's syndrome (trisomy 18): • almost every organ system affected Children rarely live more than a few months.

  15. Other Examples of Nondisjunction: Sex chromosome : Sex chromosome aneuploids • XO = Turners Syndrome • XXY = Klinefelter Syndrome • XXX = Triplo-X Syndrome • XYY =Jacob Syndrome

  16. 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)

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

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

  19. 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?

  20. Chromosome mutations (structure): translocation – a section of one chromosome is transferred to a nonhomogulous chromosome addition – a portion of a chromosome is added

  21. Chromosome mutations (structure): • deletion – a portion of a chromosome is deleted • Cri-du-Chat Syndrome (segmental deletion) • inversion – order of genes on a chromosome is changed

  22. 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 soundslike a distressed cat.

  23. In summaryChromosomal Mutations: • Chromosomal abnormalities can cause serious mental or physical disabilities, • Structure of the chromosome has been compromised • The number of chromosomes is incorrect

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

  25. Gene Mutations • Point Mutation – the substitution, addition, or removal of a single nucleotide • substitutions, 1 nucleotide in a codon is replaced with a different nucleotide, resulting in a new codon. • sickle cell anemia(also called sickle cell disease) is a point mutation substituting Adenine for Thymine in a single DNA codon,

  26. 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

  27. sickle cell

  28. Welcome to Discovery Education Player

  29. Characteristics of Mutations: • most are harmful to the organism • they are random • most are recessive traits • Can be beneficial to the organism when the mutation helps the organism to adapt to the environment.

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

  31. Human Genetic Traits & DisordersX- 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

  32. Examples of Sex linked traits: X- linked • Ex. Hemophilia –blood disorder in which blood does not clot properly • Ex. Color blindness – cannot distinguish between red and green

  33. 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/bleedingdisorders/pages/newpage26.htm Know These!!!!

  34. Ex. Hemophilia Hemophiliac male x carrier female • Genotype • Phenotype

  35. Hemophilia cont. Normal male x female carrier • Genotype • Phenotype

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

  37. Human Blood Types: Phenotype Genotype A IAIA, IAi B IBIB, IBi AB AB O ii

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

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

  40. Why? THINK! Raise your hand to answer… • WHY Blood typing important?

  41. RBC

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