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MUTATIONS

MUTATIONS. CHROMSOMES AND GENES. THE IMPACT OF MUTATION. There are 2 types of mutations 1. Chromosomal: changes in the fundamental structure of a chromosome which most likely occur during crossing over at meiosis. 2. Gene: Changes in the nucleotide sequence Both types of mutations:

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MUTATIONS

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  1. MUTATIONS CHROMSOMES AND GENES

  2. THE IMPACT OF MUTATION • There are 2 types of mutations 1. Chromosomal: changes in the fundamental structure of a chromosome which most likely occur during crossing over at meiosis. 2. Gene: Changes in the nucleotide sequence • Both types of mutations: • Can be good • Can be bad • Can have no effect on the organism (silent)

  3. Deletion of a Gene • Genes of a chromosome are permanently lost • New chromosome lacks certain genes which may prove fatal depending on how important these genes are

  4. Duplication of Genes • Genes are displayed twice on the same chromosome due to duplication

  5. Inversion of Genes • The order of genes is reversed • If essential genes are reversed, this mutation may be fatal to an organism

  6. Insertion of Genes • Information from one chromosome breaks off and is inserted into a different one

  7. Gene mutation • A single nucleotide base change in the DNA • Types • 1. Addition • 2. Deletion • 3. Substitution • First substitution mutation discovered in humans: substitution of one nucleotide for another in hemoglobin, causing sickle cell anemia • Amino acid change from glutamic acid to valine, changing normal hemoglobin to sickle hemoglobin Substitution of a base

  8. Insertion or deletion of a base

  9. Nondisjunction • Failure of paired chromosomes to disjoin during cell division so that both chromosomes go to one daughter cell and none to the other • Nondisjunction causes errors in chromosome number

  10. DOWN’S SYNDROME • Extra chromosome #21 • Head may be smaller than normal and abnormally shaped • Physical development often slower than normal • Most never reach their average adult height • May also have delayed mental and social development.

  11. TURNER’S SYNDROME • A female does not have the usual pair of two X chromosomes • Absent or incomplete development at puberty • Infertility • Absent menstruation • Short height • Have a normal, productive life

  12. Turners Syndrome: XO Klinefelter’s Syndrome: XXY Triple X Syndrome: XXX (Often no symptoms, sometimes irregular menstruation and increased risk for learning disabilities and speech impairments) What about an individual that is YO? What about an individual without sex chromosomes?

  13. KLINEFELTER’S SYNDROME • Presence of an extra X chromosome in a male • Infertility • May have enlarged breasts • Have a normal, productive life

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