1. Mutations!

2. What is a gene? Discuss, be ready to share. ◦A sequence of DNA that codes for a specific protein (or proteins) associated with a trait, characteristic, or genetic condition What do you know about mutations? Discuss, be ready to share.

3. Why does this stuff matter? DNA (and the genes in it) determine most of your characteristics. Mutations to your DNA or your ancestors’ DNA affects your characteristics. At some point, you or a family member will have medical treatment provided to you based on our knowledge about your genes and potential mutations.

4. Gene Mutations Gene mutations: occur in a single gene, usually during mitosis or meiosis ◦Gene mutations occur if DNA polymerase does its job incorrectly ◦“Point” gene mutations – occur in one/few bases (3 types) ◦1) Insertion ◦Adding a base/bases ◦2) Deletion ◦Removing a base/bases ◦3) Substitution ◦Swapping out a base/bases ◦Point mutations can have no effect, can improve the trait, or can have a negative effect on the trait.

5. Example mutation - hemoglobin What do you know about hemoglobin? Discuss, be ready to share. ◦Hemoglobin carries oxygen in red blood cells (don’t need to takes notes on this!) ◦“HBB” gene for hemoglobin on chromosome #11 (out of 23) ◦Mutant version of HBB can causes red blood cells to clump. ◦One bad gene = some clumping of red blood cells ◦2 bad genes = “sickle cell anemia” ◦http://cbm.msoe.edu/includes/swf/NewestSickleCell.swfhttp://cbm.msoe.edu/includes/swf/NewestSickleCell.swf

6. Typical hemoglobin Transcribe and translate this portion of the HBB gene: ◦GACTGAGGACTCCTC ◦mRNA: CUGACUCCUGAGGAG ◦Leucine-Threonine-Proline-Glutamic acid-Glutamic acid

7. Deletion and insertion mutations (using hemoglobin as an example) Transcribe and translate this portion of the mutated HBB gene: ◦GCTGAGGACTCCTC ◦mRNA: CACUCCUGAGGAG ◦Arginine-Leucine-Leucine-Arginine -…and extra bases (two diff a.a…) Example of a “frameshift” – all codons are “shifted” Deletion mutations (frameshift): Usually result in different primary structure  major protein problems Insertion mutations (frameshift): Usually result in different primary structure  major protein problems

8. Substitution mutations (using hemoglobin as an example) Transcribe and translate this portion of the mutated HBB gene: ◦GACTGAGGACTTCTC ◦mRNA: CUGACUCCUGAAGAG ◦Leucine-Threonine-Proline-Glutamic acid-Glutamic acid ◦Substitution mutations ◦Might not have an effect on the protein (don’t matter) ◦Could be harmful (see next slide) ◦Could put a stop codon in the wrong place ◦Could code for an incorrect amino acid with big consequences

9. Substitution mutations - 2 (using hemoglobin as an example) Transcribe and translate this portion of the mutated HBB gene: ◦GACTGAGGACACCTC ◦mRNA: CUGACUCCUGUGGAG ◦Leucine-Threonine-Proline-Valine-Glutamic acid ◦This single amino acid change completely changes the protein! ◦http://www.rpc.msoe.edu/cbm/resources/NewestSickleCell.swfhttp://www.rpc.msoe.edu/cbm/resources/NewestSickleCell.swf