Name
Date
One Wrong Letter
Tim and Allison Lord have a baby boy named Hayden
Period
1. What are your first impressions of Tim and Allison’
2. What is the first sign that there is something wrong with Hayden’s health?
3. In the Tay Sachs gene, just one letter in the DNA sequence is incorrect. Why does this cause such big
problems? What is it that actually disables and eventually kills a child with Tay Sachs disease? Be sure to
show your understanding of relationship between DNA and protein and the role of this specific protein in
your answer.
4. What is it about the relationship between Tim and Charlie Lord that made Charlie’s wife, Blyth, so
concerned when she read about Tay Sachs and found out that Tim’s son had Tay Sachs disease?
5. Tim has a son with Tay Sachs. Tim’s identical twin bother, Charlie has a daughter named Cameron. If
Charlie’s wife, Blyth just had herself tested and found out that she was a carrier of the Tay Sachs gene, what
is the probability that their daughter has and will die from the Tay Sachs disease? Explain your answer and
draw a Punnett square to justify your response. Note, you do know the genotype of both Charlie and Blyth.
6. If Blyth had not been a carrier of the Tay Sachs gene what would the probability been that their daughter,
Cameron, would have been born with, suffer from, and eventually die from Tay Sachs disease? Explain your
answer and draw a Punnett square to justify your response.
7. At the end of the clip, Tim Lord suggests that there should be a widespread push to have everybody be
tested for hundreds of genetic diseases. The tests are now widely available. If a couple finds out that they are
both carriers of Tay Sachs, but they both want to have their own child, what are their options?
8. Imagine that the couple in the last question opt to use a sperm donor who, though anonymous, is tested to
be sure that he is not a carrier of the Tay Sachs gene? What is the probability that a child of the mother who
is a carrier and the anonymous sperm donor will die of Tay Sachs? Explain your answer and draw a Punnett
square to justify your response.