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Thinking Scientifically
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1. Many articles on genetics in the popular press state, “We are now beginning to crack the genetic code,” or “Everyone has his or her own unique genetic code.” What is inaccurate about these statements?

2. How can a mutation alter the sequence of DNA bases in a gene but not produce a noticeable change in the gene’s polypeptide product? How can a mutation alter the amino acid sequence of a polypeptide yet not alter the phenotype?

3. Which biotechnology might be able to accomplish the following goals? More than one answer may be possible.


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Additional Questions and Terms

1. Why do different cell types have different rates of transcription and translation?

2. A missense mutation causes a form of Alzheimer disease by replacing a histidine with an arginine. Determine how a codon is altered in this mutation.

3. Cite two ways that proteins assist in their own synthesis. How does RNA assist in its own synthesis?

4. Many antibiotic drugs work by interfering with protein synthesis in bacteria that cause infection. Explain how each of the following antibiotic mechanisms disrupts genetic function in bacteria:

  • a. tRNAs misread mRNA codons, binding with the incorrect codon and bringing in the wrong amino acid.
  • b. Methionine is release from the initiation complex before translation can begin.
  • c. tRNA cannot bind to the ribosome.
  • d. A tRNA picks up the wrong amino acid.
  • 5. How could a mutation involving one DNA base be more devastating than a mutation involving three contiguous DNA bases?

    6. What are three ways that mutation can add amino acids to a protein?

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