DNA and Mutations

1. DNA and Mutations

2. 5 Mutation Facts • 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. Mutation = change in the DNA code • Lead to frameshifts – the message is no longer correctly passed = protein altered (changed, no change, or incomplete)

4. 3 Types of DNA Mutations: 1. • 1. Substitution - one base for another • Ex: Sickle-cell Anemia • GAG (Valine) into GUG (Glutamic acid)

5. 2. • 2. Insertion - extra bases • Ex: Fragile X syndrome – CGG repeat • 5-100 repeats = no harm • longer repeats grow longer from one generation to the next (as many as 4000 repeats).

6. 3. • 3. Deletion- a section of DNA is lost Ex: Duchenne Muscular Dystrophy (DMD) • DMD gene codes for dystrophin (protein) • protein holds skeletal muscle cells together • DMD = no protein to bind muscle cells together

7. Chromosome Mutations • Chromosome: Coiled DNA and proteins Karyotype

8. Chromosome 21 “Trisomy 21’ Down Syndrome

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

10. 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

11. 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.

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