All the information you will need to complete this murder mystery can be found on this sheet. GOOD LUCK SHERLOCK !!! Background They found Lord William’s body in the library, sprawled on the floor with a dagger in his chest. A copy of his new will, leaving all his money to charity, was found unsigned on his desk. The wealthy Lord Williams was a bachelor who had no family other than his twelve nephews and nieces. His parents and siblings were all dead. Inspectors Crick and Watson were the first officers to arrive on the scene. Before becoming a detective, Crick had dabbled in genetics. Glancing at the portrait of Lord William’s parents above the fireplace, Inspector Crick explained to those assembled that Lord Edward (William’s father) had bright red hair, caused by a recessive pair of alleles, while Lady Iris (his mother) had brunette hair, caused by a dominant allele. Crick further noted that Iris must have been heterozygous, because half or her children had been redheads. Crick and Watson questioned the family and servants and discovered that there was a witness to the murder. Remember: You are looking at TWO traits On the fateful evening a maid, upon hearing sounds coming from the library, had spied through the keyhole and seen someone wearing a long, hooded black cape. “I could not tell if it was a man or a woman, sir,” she explained, “but I did see red hair sticking out from under the hood. The person was holding a dagger behind his or her back and I noticed that the little finger of that hand was crooked. It was bent inward toward the fourth finger.” “Aha! It’s elementary, Inspector Watson!” Cried Crick. “A bent little finger is due to a single pair of alleles. If a person carries just one copy of the dominant allele, they will have a bent little finger,” Inspector Crick quickly became convinced that the culprit was a niece or nephew who stood to lose an enormous fortune if the new will was signed. To confirm his suspicions, Crick examined old family photographs and portraits, and assembled a pedigree chart (found on the back of this page). 1) Hair Colour & 2) Shape of the little finger In Order to complete this case study, there are some things that you will need to determine: 1. Use the letter “B” for hair colour and “F” for the shape of the little finger. (½ each = 5 marks TI) Let B represent _______________________ Let b represent _______________________ Thus: BB = _______________________ Bb = _______________________ bb = _______________________ Let F represent _______________________ Let f represent _______________________ FF = _______________________ Ff = _______________________ ff = _______________________ Locate the murder victim (Lord William) on the pedigree chart as well as his nieces and nephews (as one of them is the murderer). 2. Determine the genotype of ALL the individuals in the pedigree chart. Each individual has only one possible genotype. Write this genotype directly ABOVE each name in the chart. (½ each = 14 marks TI) 3. Create 12 Punnett squares (one for each marriage shown in the 2nd generation) to show your work in determining the genotypes of each member of the third generation. (12 marks TI) (Do not forget to label each square with the name of one of Lord William’s siblings.) 4. Examine the genotypes that you have assigned to each member of the 3rd generation in the chart. You must indicate their phenotype for the shape of their little finger. (12 marks APP) Write this phenotype directly BELOW each name in the chart. Summary Questions: 1. Who murdered Lord William? (! 4 marks APP !) 2. Why didn’t Inspector Crick suspect any of Lord William’s brothers or sisters? (2 marks APP) 3. What role did the dominant allele play in unmasking the perpetrator? (2 marks APP) 4. Why is David not a suspect? (2 marks APP) /31 INQ ________ /22 App ______ Lady Iris Brown Hair Straight Finger ______ _______ ______ _______ Wife Edmund Brown Red Straight Straight Catherine Brown Bent Wife Jeff Brown Brown Straight Straight ______ ________ Lord Edward Red Hair Bent Finger _______ Husband Margaret Brown Red Straight Straight ______ ______ ______ Husband Red Straight Gertrude Brown Bent Husband Brown Straight _____ Mary Red Bent ______ _____ _____ Lord William Wife Red Red Straight Straight Charles Brown Straight ________ ________ ________ _______ _______ _______ ________ _______ _______ ______ ______ ______ Douglas Red ________ Anne Red ________ Sarah Brown ________ David Red _______ Maude Brown _______ Arthur Brown _______ Abraham Brown ________ Joanna Red _______ Richard Brown _______ Timothy Brown ______ Chris Red ______ James Brown ______ Note: Not all of the third generation genotypes or phenotypes are definite. Use the family background story as well as the F1 generation punnett squares to make the most logical choice.