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HUMAN GENETICS

HUMAN GENETICS. What can go wrong?. Chromosome Gene Mutations Mutations. Chromosomal Abnormalities. 1 infant in 200 newborns has a chromosomal abnormality 28% of first trimester miscarriages have a chromosomal abnormality

jaime-tyler
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HUMAN GENETICS

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  1. HUMAN GENETICS What can go wrong? ChromosomeGeneMutationsMutations

  2. Chromosomal Abnormalities • 1 infant in 200 newborns has a chromosomal abnormality • 28% of first trimester miscarriages have a chromosomal abnormality • Abnormalities in larger chromosomes don’t usually survive

  3. MUTATION A change in the DNA code of an organism is called a ______________________ Mutations can be _______________ OR ______________ HARMFUL BENEFICIAL

  4. BENEFICIAL MUTATIONS Help an organism survive and reproduce Provide variation in population for natural selection to act upon Image from: http://www.cheryllavender.com/Snow%20Rabbit.jpg

  5. HARMFUL MUTATIONS LETHAL Can result in death =___________ (even before birth) Cause a genetic disorder Cause cancer

  6. SOMATIC CELL MUTATIONS If the change happens in a BODY CELL (lung, liver, brain, muscle, etc.) = ______________________ Somatic cell mutations can: ______________________ ______________________ _____________ Somatic cell mutation Cause cancer Make cell not able to function Kill cell • BUTwon’t be passed on to offspring

  7. GERM CELL MUTATION If the change happens in Gametes (sperm & eggs) = _______________________ Germ cell mutation • Can be passed on to offspring

  8. HUMAN GENETICS What can go wrong? ChromosomeGeneMutationsMutations

  9. Missing chromosomes (monosomy) EX: Turner’s syndrome - X0 Changes in chromosome number ____________________________ ____________________________ Extra chromosomes (trisomy) EX: Down’s syndrome – 3 #21’s Kleinfelter’s syndrome- XXy

  10. NON-DISJUNCTION A homologous pair sticks together and doesn’t separate at MEIOSIS. One cell gets 2 copies of the chromosome the other cell gets none.

  11. Normal Meiosis

  12. Nondisjunction

  13. Nondisjunction • Chromosomes don’t separate at anaphase • Cell gets 2 copies of a chromosome OR none • After fertilization new baby gets 3 of each chromosome (trisomy) or only 1 copy of each (monosomy)

  14. Normal division Non-disjunction

  15. Human Abnormalities Caused by Non-Disjunction Down’s syndrome Patau syndrome Kleinfelter syndrome Turner’s syndrome Xyy

  16. Turner’s syndrome(monosomy)

  17. Turner’s syndrome XO • 1 in 5000 births • Female = XO • Small size • Slightly decreased intelligence • 35% have heart abnormalities • Hearing loss common • Broad chest • Undeveloped ovaries/can’t have children

  18. Kleinfelter syndrome Xxy(trisomy)

  19. Kleinfelter syndrome • 1 in 1000 births • Male = XXy • Average to slight decrease in intelligence • Small testes/ can’t have children • Usually not discovered until puberty when don’t mature like peers

  20. Xyy syndrome • Xyy males • Taller • Average intelligence • Some study show increased learning disabilities • Lead normal lives

  21. Down’s syndrome (trisomy 21)

  22. Down’s syndrome (trisomy 21) • 1 in 660 births • Similar facial features • Slanted eyes • Protruding tongue

  23. Down’s syndrome (trisomy 21) Simian line on palm

  24. Down’s syndrome (trisomy 21) • Most common chromosomal abnormality • 50% have heart defects that need surgery to repair • Mental retardation • Risk increases with age of mom

  25. Patau syndrome (trisomy 13)

  26. Patau syndrome (trisomy 13) • Can be traced back 300 years in literature • 1st identified as a chromosomal cause in 1960 • 1 in 7000 births (rare)

  27. Patau syndrome (trisomy 13) Cleft lip & palate Eye abnormalities (too small or missing)

  28. Patau syndrome (trisomy 13) Low set ears Polydactyly

  29. HUMAN GENETICS What can go wrong? ChromosomeGeneMutationsMutations

  30. DELETION Piece of whole chromosome is lost ________________________________________ Image from: http://www.biology-online.org/2/8_mutations.htm

  31. Human Abnormalities Caused by Deletions • Wolf-Hirschhorn syndrome • Cri-du-chat syndrome • Prader-Willi Syndrome

  32. Wolf-Hirschhorn syndrome (4p-) • Missing piece on short arm of chromosome 4 • Mental retardation • Large low set ears • Club feet

  33. Cri-du-chat (Cat cry) (5p-) • 1 in 50,000 births • More common in girls

  34. Mewing cry in infancy • Missing piece of number 5 • Mental retardation • 50% have heart defects

  35. Prader-Willi Syndrome • Deletion in chromosome 15 • Feeding problems: poor weight gain in infancy, won’t eat • Ages 1-6 excessive, rapid weight gain • Under developed sex organs • Mild to moderate retardation • Obsession with food • Complications from problems associated with obesity (heart attack, high blood pressure, diabetes)

  36. Prader-Willi syndrome Victor at age 1 Victor at age 2

  37. INVERSION Segment flips and reads backwards Image from: http://www.biology-online.org/2/8_mutations.htm

  38. TRANSLOCATION Segment breaks off and joins a different non-homologous chromosome Image from: http://www.biology-online.org/2/8_mutations.htm

  39. A gene that is flipped and reads backwards will not work. A gene that is moved to another chromosome will not separate from its partner during meiosis. One cell can get 2 copies of gene, one cell gets none.

  40. HUMAN GENETICS What can go wrong? ChromosomeGeneMutationsMutations

  41. GENE MUTATIONS Changes in the DNA code of a single gene DNA  RNA PROTEIN  ___________ ____________ ______________________

  42. Harmful Gene Mutations SINGLE 1. Point mutations – changes a _________ base in DNA code 1. __________________ 2. Frame shift mutationschanges _____________ bases in code 1. ___________________ 2. ________________ Substitution MULTIPLE Deletion Addition

  43. SUBSTITUTION Changes one base for another A T T C G A G C T A T T C T A G C T

  44. SICKLE CELL ANEMIA CAUSE: (autosomal recessive) A changed to T(glu to val) gene on chromosome #11 that codes for part of hemoglobin protein (carries oxygen in blood)

  45. SICKLE CELL ANEMIA SYMPTOMS: Sickle shaped Red Blood Cells in hh persons Circulatoryproblems Loss of blood cells (anemia) Organ damage DEATH

  46. SICKLE CELL ANEMIA More common in African Americans 1 in 500 = hh 1 in 10 = Hh carriers for gene Hh persons have Sickle cell TRAIT make some normal RBC’s’ ; some sickled cells

  47. FRAME SHIFT MUTATIONSChanges multiple bases in code thefatcatranandran ____________________ DELETION theatcatranandran _____________________ the fat cat ran and ran the atc atr ana ndr an

  48. FRAME SHIFT MUTATIONSat beginning of gene are more damaging than those at end because more of gene is changed thefatcatranandran ____________________ DELETION near front theatcatranandran _____________________ DELETION near end _____________________ the fat cat ran and ran the atc atr ana ndr an thefatcatranandrn

  49. DELETION Piece of DNA code for one gene is lost ________________________________________ Image from: http://www.biology-online.org/2/8_mutations.htm

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