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Molecular Biology Review module of the MLA course on Introduction to Molecular Biology Information Resources
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Reading Frames

A reading frame refers to one of three possible ways of reading a nucleotide sequence.

Let's say we have a stretch of 15 DNA base pairs:

       acttacccgggactg
  • We can start translating, or reading, the DNA from the first letter, 'a,' which would be referred to as the first reading frame.
  • Or we can start reading from the second letter, 'c,' which is the second reading frame.
  • Or we can start reading from the third letter, 't,' which is the third reading frame.

The reading frame affects which protein is made. In the example below, the upper case letters represent amino acids that are coded by the three letters above them.

schematic diagram of gene control

Molecular Biology Review
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Revised 11/01/2007