BIO120H1 Study Guide - Midterm Guide: Advantageous, Chromosome, Multicellular Organism
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BIO120H1 Full Course Notes
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Where does variation come from? (australian daisy example) Selection: some forms are more successful at surviving and breeding than others in a given environment. Mutation (the ultimate source of genetic variation): A stable change in the dna sequence occurring at a low but variable rate. Caused by typographical errors in copying even though there are mechanisms in cells to correct errors in replication. Effects can be: neutral, deleterious, lethal, or beneficial. It"s ransom and is not directed by the organism or the environment. Environment insults can affect the rate (ex: mutagens) Beneficial mutations are extremely rare but over time with large enough population then populations are experiencing the most possible mutations over sufficient time and eventually will hit a good mutation. Types: point mutationsatgcagt atccagt (simplest and most common, insertions/deletionsatgcagt atggcagt, changes in repeat numberatgatgatgatg atgatgatgatgatg (forensics, chromosomal rearrangements atgcagt tgacgta. Example: drosophila with antennae vs. no antennae due to a single nucleotide polymorphism.
