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Warm up

Warm up. How much of the DNA is affected in a gene mutation?. Karyotypes & Chromosome Mutations. Karyotypes Photograph of an individual’s chromosomes Human karyotypes show 23 pairs of homologous chromosomes . 46 chromosomes or 23 pairs. Sex Determination

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Warm up

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  1. Warm up • How much of the DNA is affected in a gene mutation?

  2. Karyotypes & Chromosome Mutations

  3. Karyotypes • Photographof an individual’s chromosomes • Human karyotypes show 23pairs of homologous chromosomes. • 46 chromosomes or 23 pairs

  4. Sex Determination • Autosomes/autosomal chromosomes– (22 pairs) #1-22 • determine body traits and they are homologous • Sex chromosomes – (#23) not really homologous, determines sex • Males – sex chromosomes are different –XY • Females –XX Box & Label the Autosomal Chromosomes Circle & Label the Sex Chromosomes

  5. Think & Share • To have a girl, the mother passes on her __ chromosome and the father passes on his __chromosome. • To have a boy, the mother passes on her __ chromosome and the father passes on a __chromosome. X X X Y

  6. Changes in Chromosomes: • Mutation: a random change in the sequence of nucleotides in DNA orthe structure of chromosomes • Two categories of mutations: Gene Mutations and Chromosomal Mutations

  7. Chromosome mutations • Mutation to the entire structure of the chromosome • Often caused by non-disjunction • chromosome pairs fail to separate during Meiosis. • Result: a cell with too many or too few chromosomes. Cell(s) may die

  8. Non-disjunction: • occurs when chromosome pairs do not separate properly during anaphase. • Once cell receives one or more extra chromosomes and the other cell receives zero chromosomes. • In Mitosis one cell may die. • In Meiosis, two cells may not survive if nondisjunction occurs in Meiosis I. One cell may not survive if nondisjunction occurs in Meiosis II.

  9. Non-disjunction In Meiosis 1 In Meiosis 2

  10. Monosomy • Only one chromosome of a paired chromosome is present • Usually caused by an error during mitosis or meiosis called non-disjunction

  11. Trisomy • Three chromosomes are present in a chromosome pair • Also caused by non-disjunction

  12. Polyploidy • Non-disjunction occurs in all chromosome pairs • Multiple chromosomes in each pair • Offspring will usually not live, but some plants with polyploidy may be healthier or beneficial to mankind (strawberries are octoploidy)

  13. Turner syndrome – • only 45 chromosomes, missing a sex chromosome (X) • Girls affected only – slow growth, heart problems, nonverbal learning difficulties, webbed neck (excess or stretched skin), slight droop to eyes, incomplete puberty (premature ovarian failure)

  14. Turners Syndrome 96-98% do not survive to birth No menstruation No breast development No hips Broad shoulders and neck

  15. Examples: Down’s syndrome – (Trisomy 21) 47 chromosomes, extra chromosome at pair #21

  16. Klinefelter syndrome – • 47 chromosomes, extra X chromosomes (XXY) • Boys affected only –  taller, low testosterone levels result in less muscular body, less facial and body hair, in fertility But some men may only show symptoms of infertility. http://learn.genetics.utah.edu/content/disorders/whataregd/klinefelter/

  17. Jacob’s Syndrome • 1 in 1,800 births • 47 chromosomes (XYY) • #23 Trisomy • Symptoms • Tall stature • Acne • learning problems at school and delayed emotional maturity • Real Life Story

  18. Triple X Syndrome • 1 in 1,000 • Trisomy 23 (XXX) • Symptoms • taller than average • no unusual physical features • normal sexual development and are able to conceive children. • risk of learning disabilities • delayed development of speech, language skills, motor skills • weak muscle tone • behavioral and emotional • Seizures or kidney abnormalities (10% of affected females)

  19. Edward’s Trisomy Syndrome • 1 in 4,400 births • 47 chromosomes • XX=80% XY=20% • #18 Trisomy Nondisjunction • Symptoms • Small head • Mentally retarded • Internal organ abnormalities • 90% die before 5 months of age

  20. Patau’s Trisomy Syndrome 1 in 14,000 births 47 chromosomesXY or XX #13 Trisomy Nondisjunction

  21. Patau’s Trisomy Syndrome Small head Small or missing eyes Heart defects Extra fingers Abnormal genitalia Mentally retarded Cleft palate Most die a few weeks after birth

  22. Polyploidy: • Multiple sets of chromosomes • Having an extra set of chromosomes is fatal in animals, but in plants it makes them larger and hardier. Polyploid karyotype of a fetus that did not survive. Plant polyploid karyotype

  23. Ticket out • Describe at least one similarity and difference between a gene mutation and a chromosome mutation.

  24. Other Chromosome Mutations

  25. Deletion: • Occurs when a piece of a chromosome breaks off and is lost • Some deletions are lethal, some are not. • EX: Del.tion • Example: Cri-du-chat-- disorder that involves a deletion of a region on human chromosome 5

  26. Aniridia-Wilms Tumor Syndrome • 1 in 50,000,000 births • 46 chromosomesXY or XX • #11 Partial Deletion • Symptoms • Mentally retarded • Growth retarded • Blindness • Tumors on kidneys • Short lifespan

  27. Prader-Willi Syndrome • 1 in 5,000,000 births46 chromosomes • XY=97% XX=3% • #15 Partial Deletion • Symptoms • Small bird-like head • Mentally retarded • Respiratory problems • Obesity • Short lifespan

  28. Duplication: • Occurs when part of a chromosome breaks off and is added into its homologous (sister chromosome) • The homologous chromosome then has extra copies of genes • EX: Dupliplication

  29. Translocation • A chromosome part breaks off and attaches to a different, non-homologous chromosome • May result in too many or too few genes in a chromosome and can affect organisms in several ways • Can cause cancer • May go undetected, but may face reproductive issues • Ex: locaTranstion

  30. Inversion • Invert: to turn upside down or reverse • Part of a chromosome breaks off, turns around, and reattaches in the reverse order • Changes the order of the genes but not the number of genes • so it generally causes less harm than deletions or duplications • Often undetected, but may decrease fertility • EX: noisrevnI

  31. Four-Ring Syndrome 1 in 10,000,000 births 46 chromosomesXY or XX #4 Inversion

  32. Four-Ring Syndrome Cleft palate Club feet Testes don’t descend Short lifespan

  33. Inversion of chromosome 15q • Mother had inversion • Child had inversion and duplication • “mild dysmorphicfeatures”-- “prominent nasal root, large prominent eyes, and micrognathia. He also had dislocated hips, severe talipesequinovarus”

  34. Chromosomal mutation: • Drastic effects – affects entire chromosome, so affects many genes rather than just one • Caused by : • A failure of the homologous chromosomes • toseparate normally during meiosis– non-disjunction • An error during meiosis • Chromosome pairs no longer look the same – too few or too many genes, different shape

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