Summary
Flexible pairing at the third codon position lets fewer tRNAs read all 61 sense codons.
In depth
Crick proposed that the base at the 5' end of the anticodon can pair loosely with the 3' base of the codon; inosine in the anticodon pairs with U, C or A. This allows about 40 tRNA types to read 61 codons.
Wobble explains why most degenerate codon variation is at the third position.
Wobble explains why 61 sense codons can be read by fewer than 61 tRNAs. The first position of the anticodon (34) pairs with the third codon base, and modified bases such as inosine and queuosine expand pairing. A G in this position can pair with C or U, and U can pair with A or G.
The first two codon positions pair by strict Watson-Crick rules, so the third position changes often leave the amino acid unchanged, which fits the pattern of the code, in which amino acid families share the first two bases. Wobble also helps minimise errors by being limited to certain pairs.
Example: the codons GCU, GCC and GCA for alanine can be read by a tRNA with inosine in the anticodon.
Frequently asked questions
What is Wobble Hypothesis?
Flexible pairing at the third codon position lets fewer tRNAs read all 61 sense codons.
Which area of biology covers Wobble Hypothesis, and how advanced is it?
Wobble Hypothesis is one of the 52 topics in Molecular Biology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Transfer RNA, Codon, Translation.
Can you give an example of Wobble Hypothesis?
A single tRNA with an anticodon of GAA can read UUC and UUU codons for phenylalanine.
What should I learn before Wobble Hypothesis?
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to Wobble Hypothesis. Advanced topics assume the Intermediate vocabulary.
What topics are related to Wobble Hypothesis?
The closest topics to Wobble Hypothesis are Transfer RNA, Codon, Translation, Base Pairing. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Wobble Hypothesis?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Wobble Hypothesis. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
How is Wobble Hypothesis different from Transfer RNA?
Wobble Hypothesis: Flexible pairing at the third codon position lets fewer tRNAs read all 61 sense codons. Transfer RNA: Small RNA adaptors with an anticodon that bring the correct amino acid to the ribosome. Read both side by side and note what each one explains.
How should I study Wobble Hypothesis step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Transfer RNA and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.