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Homework answers / question archive / In the absence of our regular face-to-face interaction in our class, please participate in a discussion with other students about what topics from this week have been most interesting or difficult
In the absence of our regular face-to-face interaction in our class, please participate in a discussion with other students about what topics from this week have been most interesting or difficult. In the same discussion, please share why you thought it was interesting or why you experienced difficulties with these topics and how you have improved your understanding.
You should include any recommended study tips, review videos, or other materials you used to follow up on or help improve your understanding of the topic(s). Please respond to at least two other students in this discussion board - you can choose to respond by helping others out with suggestions for studying, you can choose to respond to students who had difficulties with the same topics as you, you can choose to respond to students who found the same topic interesting, etc.
Your discussion should include:
Grading Rubric:
Your participation in the discussion board is graded. Please see the grading rubric for more information
This week’s lecture was a little difficult for me. To be specific the different methods of dating fossils were difficult for me. Watching that part of the lecture twice helped a little. It is really important to know the specific age of a fossil. The one topic I found to be interesting was the concept of using mitochondrial DNA as a molecular clock. The molecular clock measures the number of changes, or mutations, which accumulate in the gene sequences of different species over time. Evolutionary biologists can use this information to determine how species evolve and the date when two species diverged on the evolutionary timeline. The setting of a molecular clock begins with a known, such as the fossil record of a specific species. Then, once the rate of mutation is determined, it is possible to calculate the time. For example, if the rate is 5 mutations for every million years, and 25 mutations are counted in the DNA sequence, then the sequences diverged 5 million years ago. Different genes evolve at different rates. The evolution of important genes occurs more slowly than that of the genes with less vital functions. More rapidly changing genes are used to date more recent evolutionary events and the genes that evolved slowly are used to map more ancient divergences. Molecular clocks are useful in obtaining evolutionary records of organisms with little to no fossil records. For example, fungi are soft and squishy and don't turn into fossils. But, it is possible to take the rate of change of genes from vertebrates or plants, which have a decent fossil record, and apply it to an unknown group such as fungi. Molecular clocks can also be used to put different evolutionary events into chronological order.
