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Which of the following is the BEST explanation of the role of DNA and RNA in making proteins? a DNA unwinds into two separate strands, and an exact copy of each is produced during replication. During translation, a DNA strand is used to produce a complementary strand of mRNA, with uracil taking the place of thymine. During transcription, each set of three codons in the mRNA results in an amino acid being added to a chain, and a protein is formed. b DNA unwinds into two separate strands, and a complementary copy of each is produced during replication. During transcription, a DNA strand is used to produce a complementary strand of mRNA, with uracil taking the place of adenine. During translation, each base in the mRNA results in an amino acid being added to a chain, and a protein is formed. c DNA unwinds into two separate strands, and an exact copy of each is produced during replication. During transcription, a DNA strand is copied to produce mRNA, which is an exact copy of the DNA strand except that uracil takes the place of thymine. During translation, each set of three bases in the mRNA results in a protein with a specialized function being formed. d DNA unwinds into two separate strands, and a complementary copy of each is produced during replication. During transcription, a DNA strand is used to produce a complementary strand of mRNA, with uracil taking the place of thymine. During translation, each set of three bases in the mRNA results in an amino acid being added to a chain, and a protein is formed.

1 answer

The BEST explanation of the role of DNA and RNA in making proteins is option d:

d: DNA unwinds into two separate strands, and a complementary copy of each is produced during replication. During transcription, a DNA strand is used to produce a complementary strand of mRNA, with uracil taking the place of thymine. During translation, each set of three bases in the mRNA results in an amino acid being added to a chain, and a protein is formed.

Explanation for Choosing Option D:

  1. Replication: DNA unwinds and each strand serves as a template to create a complementary strand. This is correctly stated in option d.

  2. Transcription: The process of forming mRNA from a DNA template involves replacing thymine with uracil (correctly noted in option d).

  3. Translation: Each set of three bases (codons) in mRNA corresponds to an amino acid. The phrasing "set of three bases" is accurate as it highlights the triplet nature of codons, which is essential for the formation of amino acid chains during protein synthesis.

Why Other Options are Less Accurate:

  • Option A: Incorrectly states that a DNA strand is used to produce mRNA in translation.
  • Option B: Incorrectly claims that uracil replaces adenine during transcription.
  • Option C: Misstates that mRNA is an exact copy of the DNA strand (it is complementary, not exact, as uracil replaces thymine).

Thus, option d presents the clearest and most accurate explanation of these fundamental processes.