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Thinking Scientifically
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  1. In one strain of bacteria you observe an x amount of some enzyme. In a mutant derived from that strain there is 1.5 times the amount of the enzyme. A comparison of the sequence of the two strains shows that there is no change in the coding region of the gene. But there is a substitution of two A-T base pairs in the mutant for two G-C base pairs. About 10 nucleotides before the location where transcription actually begins. What hypothesis would explain how such a mutation could produce this change in protein level? What other change would be predicted?
  2. Changes in DNA sequence, that is, mutations, account for evolutionary changes. Sometimes evolution seems to occur quite rapidly. What type of change in DNA sequence might bring about the greatest change in a protein and the greatest phenotypic change immediately?

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