Evolution Lessons

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Tutorial: Investigating Evolutionary Questions Using Online Molecular Databases: SYNOPSIS Students are guided through a process in which three questions are addressed by retrieving beta hemoglobin sequences from online databases, and using online tools to compare those sequences in student-selected animals. The questions: (1) Are bats birds, or mammals?; (2) Are whales more closely related to artiodactyls, or perissodactyls?; and (3) should birds be included in the class Reptilia?
PRINCIPAL CONCEPT: Degrees of biological relationship can be inferred from comparisons of selected molecules.


Molecular Sequences & Primate Evolution (beta Hemoglobin):
SYNOPSIS: Students compare differences in amino acids in the beta hemoglobin from representative primates, complete a matrix of those differences, and from these data, construct and interpret cladograms as they reflect relationships and timing of divergence.
PRINCIPAL CONCEPT: Modern apes and humans evolved from a common ancestor.

Molecular Biology & Phylogeny (cytochrome c):
SYNOPSIS: Amino acid sequences in cytochrome-c are compared for several different animals, and the number of differences found are used to infer degrees of relationship. These data are also compared with a cladogram constructed for those same animals from their anatomical features, providing an example of independent confirmation.
PRINCIPAL CONCEPT: Independent confirmation strengthens scientific inferences.

Chromosome Fusion - and Inquiry: Seeking Molecular Fossils
SYNOPSIS: The banding pattern of our long chromosome #2 closely matches the banding patterns of two shorter chromosomes found in apes. This suggests the likelihood that our #2 chromosome was formed by the head-to-head fusion (merging) of those two shorter chromosomes in an early human ancestor. To test that hypothesis, students search for evidence (molecular fossils) of this fusion in the DNA of chromosome #2, using online databases (or printouts of same) to seek the sequences typical of terminal DNA (telomeres). In the process, students see how patterns can reveal events of the past, thereby merging elements of both experimental and historical science. They discover the huge amount of DNA in a chromosome, get a sense of gene size and the number of pseudogenes, correlate visible chromosome bands and their contained DNA, and learn to use an accessible resource for further study and inquiry.
Or try the easier-to-teach variation: Mystery of the Matching Marks (Telomeres). Uses PowerPoint with short DNA search for the tell-tale telomers in our #2 chromosome to test the hypothesis that we share a common ancestor with the chimpanzees..
PRINCIPAL CONCEPT: Modern apes and humans evolved from a common ancestor.

Whale Ankles and DNA: Testing hypothesis that the closest living relative of whales is the hippo.

Pseudogene Suite (2 lessons: A and B): Vitamin C and Common Ancestry:
SYNOPSIS: Students compare the DNA sequence data for a portion of the rat GULO gene (which helps make vitamin C) to the corresponding sequence in the inactive human GULO gene by translating the sequences and by aligning them. This lays ground work for exploring pseudogenes and the significance of these DNA sequences in recognizing shared common ancestry vs the notion of "intelligent design" (Lesson B).
PRINCIPAL CONCEPT: Mutation may create an inactive version of a gene (an inactive allele), and, over generations, the active gene (allele) may be lost from the species, leaving only the inactive gene (pseudogene).

Click HERE for excellent article on Moledular Clues to Evolution