Protein Synthesis 1

Protein Synthesis 2


Now that an mRNA copy has been made, the DNA zips back up and can be used again later to make more copies. Remember, the mRNA copy is also a genetic code for how to make a protein. The code was originally copied from the DNA which is much too valuable to be used itself to make the protein. So a copy was made, called mRNA.

The mRNA moves into the cytoplasm where the code will be translated on a ribosome by transfer RNA (tRNA) molecules.

Each tRNA carries one specific amino acid which will be needed to build the protein. Since a protein consists of a precise sequence of amino acids, the right tRNA must insert it's amino acid into the chain when needed. How does this happen?

On one end of a tRNA molecule is the amino acid.
On the other end is a set of 3 bases called an anticodon (ie. CGA). The 3 anticodon bases use complementary base pairing with 3 mRNA bases (called a codon, ie. GCU) and if they fit, this is the correct tRNA molecule and therefore, the correct amino acid. See how the tRNA anticodon, CGA, is complementary to the mRNA codon, GCU? And note that both tRNA and mRNA have Uracil instead of Thymine.

Since the tRNA's are essentially "reading" the mRNA code (by binding to it) and bringing in the proper amino acids to build the protein, this process is called Translation.

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The mRNA sequence that was transcribed in the first step of protein synthesis is shown with 3 tRNA's below it, each of which carries a "generalized" amino acid (in this problem). Place the correct bases in position to make up the tRNA anticodons. Place additional symbols to fully label the process.
High school biology website with flash animations. Requires current Flash player.
  1. What organelle assists tRNA in translating the mRNA in the cytoplasm?


  2. The role of tRNA is to carry a(n):


  3. Is a tRNA anticodon more similar to DNA or RNA in nucleotide sequence?


  4. If the mRNA codon is CGA, the tRNA anticodon that binds with it is:


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© Copyright 2008, E. Kimmel