17. Which of the following molecules has an amino acid attached to it?
a. DNA            b. tRNA         c. mRNA         d. all of the above

There is a diagram of tRNA on page 233 of your text. Note that tRNA is a relatively small RNA molecule. It has two regions that are significant.   At one end of the molecule is a sequence of three bases that will pair with a codon of mRNA in a complementary fashion.  This sequence of bases in tRNA is called an anticodon (for obvious reasons!).  Depending on what the particular anticodon is, at the other end of the molecule is a region that will pick up a specific amino acid.   Note: to determine the type of amino acid carried, one reads the mRNA codon.   Thus, if the base sequence of mRNA in a region is UUU(a codon), this will attract a tRNA molecule with an anticodon AAA. Look at the codon chart on page 231 of your text. This tRNA molecule with the anticodon AAA will carry the amino acid Phe (phenylalanine).

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Emma Erdahl, Associate Professor of Biology
Northern Virginia Community College
Revised 8/23/00