Lab Manual - eScience Labs

Lab 15: Populaon Genecs
Quesons
1. How many total base pairs are in all the mammalian genes?
2. What proporon (%) of the total genome does this represent?
3. What is the probability that a random mutaon will occur in any given gene?
4. Only 1 out of 3 mutaons that occur in a gene result in a change to the protein structure. What
is the probability that a random mutaon will change the structure of a protein?
Some mutaons do change the protein coded for by a gene. The vast majority of these mutaons are
lethal and the embryo never fully develops. Occasionally mutaons do not effect embryonic development
and the offspring is born without complicaon.
Natural selecon is a selecon pressure that acts on phenotypes in one of three ways:
• It will confer an adapve advantage, an adapve disadvantage, or remain enrely neutral.
• A classic example to illustrate natural selecon comes from England.
• Prior to the Industrial Revoluon the nave moths were predominantly a light color, though
darker versions of the same species existed.
The lighter color blended with the light bark of the local trees, while the darker moths experienced a
higher predaon rate – they were easier for birds to spot and fewer survived to reproduce. As England
entered the Industrial Revoluon they began burning fossil fuels with lile regard to the pollutants
they were eming. The trunks of the trees became coated with soot and the color darkened. The
lighter moths became more conspicuous and the darker were beer camouflaged. The proporon of
white to dark moths changed.
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