Q2 - Contamination and Degradation in Ancient DNA
Mark Thomas (1964-present) read the first DNA sequences from woolly mammoths (Mammuthus primigenius). However, ancient DNA analysis remains difficult, due to degradation, contamination, and polymerase inhibitors found in the samples. Scientists attempted to extract DNA from a dinosaur fossil and analyse the sequence of one specific gene. The following phylogeny was produced after comparing the sequence against other species.
Using the information and data, determine which of the statements are true or which are false.
A. When working with ancient samples, it is easier to recover DNA sequences from a mitochondrial gene than a nuclear gene of the same length.
B. It is better to sequence very long DNA fragments from ancient samples, than very short fragments.
C. Adding a DNA fragment of a known sequence could show whether or not samples contain polymerase inhibitors.
D. This dinosaur fossil extract is likely to contain contaminating DNA.
Question reproduced from IBO 2017, Theoretical Exam A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions