Review Questions for lecture 17

Review Questions for lecture 17 - Review Questions for...

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Review Questions for lecture 17 Be comfortable with the following terms: Species Pseudogene Natural Selection/Selection pressure Genetic Drift Lateral gene transfer Homology Synteny Orthologous genes Paralogous genes Fluorescence In Situ Hybridization (FISH) Genetic Drift Neutral Mutation Selection Multi-Locus Sequence Typing (MLST) ecotype Genomic Island Metagenome of an environment “artificial” selection Enrichment culturing Metagenomics Isotopic labeling Limiting nutrient A classic “pre-genomic” way to tell the difference between E. coli and Salmonella is that E. coli can digest lactose—thanks to the famous lac operon. Would a single base change in the E. coli lac operon that caused a nonsense mutation change E. coli into Salmonella ? Why is rRNA sequence a more reliable measure of what species a cell belongs to? A single base change that makes E. coli unable to digest lactose is rare. Would it be possible for a second single base mutation to restore E coli ’s ability to digest lactose? How could the environment “find” such a rare mutant? In most cases, relatively few (<20%) of the amino acids in a given protein are absolutely conserved; the rest can be substituted by related amino acids (e.g. valine for isoleucine). Can phenotypically neutral mutations accumulate in orthologs to such a degree that recombination between them is unlikely? Why does selection favor smaller genomes in parasitic organisms? Do cells actively get rid of unneeded genes? Describe the process by which a gene becomes a pseudogene. If one cell in a population of billions has a single-base change nonsense mutation in a totally unused gene, does it have a selective advantage, disadvantage, or no advantage? If one cell in a population of billions has a 10 base deletion in a totally unused gene, does it have a selective advantage, disadvantage, or no advantage? What sort of selection pressure favors larger genomes? Describe, in as much detail as you can muster, how a genome gets larger. You may use the example of a non- phototrophic heterotroph living in a sunny environment acquiring the 12 genes required for rhodopsin-based phototrophy. What sort of selection pressure favors smaller genomes?
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Review Questions for lecture 17 - Review Questions for...

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