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DNA and Mutations

DNA and Mutations . Mutation Facts #1-5 . Write down five facts about mutations as we go through the following videoclips Video 1 Video 2 – Repair Video 3 – Repair Addition and Deletion Mutations. What is a Mutation? . change in the DNA code

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DNA and Mutations

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  1. DNA and Mutations

  2. Mutation Facts #1-5 • Write down five facts about mutations as we go through the following videoclips • Video 1 • Video 2 – Repair • Video 3 – Repair • Addition and Deletion Mutations

  3. What is a Mutation? • change in the DNA code • Lead to frameshifts – the message is no longer correctly passed • Protein Outcomes: • 1. changed – different from the original • 2. no change - silent mutations • 3. incomplete - amino acid is changed to a "stop" codon

  4. 3 Types of Mutations: • 1. Substitution - one base for another • Sickle-cell Anemia • GAG into GUG • Valine becomes glutamic acid

  5. 2. Insertion - extra bases • Huntington's disease – CAG repeat • fragile X syndrome – CGG repeat

  6. Fragile X syndrome • triplet CGG is repeated (CGGCGGCGGCGG, etc.). • repeats as few as 5 or as many as 50 will not cause harm. Even 100 repeats usually cause no harm. • longer repeats have a tendency to grow longer from one generation to the next (as many as 4000 repeats).

  7. 3. Deletion - a section of DNA is lost, or deleted. • DuchenneMuscular Dystrophy (DMD) • DMD gene codes for dystrophin (protein) • protein holds skeletal muscle cells together - missing in DMD

  8. Mutations lead to Genetic Disorders • One Wrong Letter - Tay Sachs • Finding Cures is Hard - Cystic Fibrosis

  9. Chromosome Disorders • Chromosome: Coiled DNA and proteins

  10. Chromosome Arrangement • Called a Karyotype • Receive one from mom, one from dad, they are homologs

  11. Chromosome 21 “Trisomy 21’ Down Syndrome

  12. Kleinfelter’s syndrome- XXY • Male • Develop some breast tissue • Little body hair • typically tall • Infertility results - no sperm

  13. Turner’s Syndrome– X • No Y means Turner’s people are female. • no ovaries develop don’t undergo puberty and they are sterile. • Hormone treatment cures all but the sterility. • Other symptoms: short stature, webbed skin and low hairline at the neck

  14. Mutations – good or bad? • Discuss with your lab partner.

  15. Reflection • DNA codes for proteins. If DNA is mutated, how might this cause a disease? (Connect proteins to disease). • How is it possible for two identical twins, with identical DNA sequences, have different traits – for instance one gets cancer and one does not.

  16. What is Epigenetics? • the study of changes in phenotype (appearance) or gene expression caused by mechanisms other than changes in the DNA

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