How is the selection of the Heike Crab Different From The Selection of Sickle Cell Anemia?

14. How is the selection of the Heike Crab Different From The Selection of Sickle Cell Anemia?

15. Limulus polyphemus

16. Horseshoe Crab Blood • Blue • Is used in the LAL test, which assesses the safety of drugs by clotting in the presence of bacteria • Also shows that the crabs share arachnid lineage (evolved from chelicerates, not crustaceans)

17. Cytochrome C • Small protein (100-104 amino acids long) found in the mitochondria of many species • Involved with electron transport chain

18. Cytochrome C and Cladistics • Used as evidence for divergent evolution • Humans and rhesus monkeys only differ in the 66th of 104 amino acids. Humans and chimpanzees have NO differences. • If N = amount of time for one nucleotide in cytochrome C to mutate, then we can calculate when two species diverged as (N) (# of mispaired nucleotides)

19. Lab: Cladistics of Cytochrome C • Purpose: To compare and contrast the cladistics relationships of nine organisms based upon biochemical differences in their cytochrome c sequences • Method: Comparative biochemistry and cladogram analysis

20. Protocol 1: Comparison of Amino Acids Sequences • 1) Obtain a chart of the cytochrome c sequences for 20 species • 2) For the species identified in table 1 of your lab handout, compare their cytochrome c sequences and note how many differences exist between the amino acids of their proteins. • 3) Record the total number of differences in table 1

21. Protocol 2: Cladogram Construction • 1) Review your table and select the two most closely related species based upon the fewest number of differences in their cytochrome c sequences. Make them the shortest branches on the cladogram (see diagram in handout) • 2) Place the next two closest species on the next branches of the cladogram • 3) Repeat until all of the species have been placed appropriately