For the questions below, you are given a scenario, type of mutation, and/or a disease with a specific genetic condition. (You do not need to know anything about the specific diseases. This question is about the mutations). Explain what could cause the problem (what would cause this type of mutation? Often there is more than one correct answer - you only have to state one) and by what mechanism it could have occurred (the answer here needs to match the cause you identified -for example, if you chose a tautomer shift to cause your substitution, for this part you should explain HOW this tautomer shift causes the mutation.) In addition, give a brief description of how this issue could have been repaired before it caused a permanent mutation. Scenario 1: A substitution mutation in the DNA that codes for the cone photoreceptors in your eye can cause color blindness. Oftentimes, only one color is knocked out. The various proteins are coded for on different places on the DNA, which makes a substitution unlikely to occur in all three genes. What is a possible cause and mechanism of this substitution mutation? What is the repair mechanism?
Scenario 2: In myotonic dystrophy type one, there is an expansion of the cytosine-thymine-guanine (CTG) triplet repeat in the DMPK gene. This leads to loss of muscular function where often time the muscles contract, but do not relax. This can lead to cataracts, cardiac conduction problems, and intellectual disabilities. What is a possible cause and mechanism of this trinucleotide repeat disorder? - What is the repair mechanism?
Scenario 3: A single insertion or deletion mutation in the HEXA gene on chromosome 15, which encodes for the alpha-subunit of beta-N-acetylhexosaminidase A, causes the autosomal recessive disorder known as Tay-Sachs Disease. What is a potential cause and mechanism of this insertion or deletion mutation? ABC - What is the repair mechanism?