I was searching in Google about polar and Non polar amino acids but the answers were not that accurate. Many examples were common in both polar and Non polar amino acids and also I did not get any clear information regarding the types of R groups present in both of these types.

So, Which variable (R) groups should be present in an amino acid to make it a polar amino acid? Also can you please give some examples of both of these types?

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  • $\begingroup$ Don't you know yourself what is polar and what is not? $\endgroup$ Commented Jun 10 at 19:58
  • 3
    $\begingroup$ Since you think the answers you found are inaccurate, please explain, in the question, where they're wrong. I.E., show your work. $\endgroup$ Commented 2 days ago
  • 1
    $\begingroup$ I think even sharp division between them is inaccurate. $\endgroup$
    – Mithoron
    Commented 2 days ago
  • $\begingroup$ Take a look at hydropathy indices like Kyte-Doolittle. $\endgroup$
    – Karsten
    Commented yesterday

1 Answer 1


If you're unsure whether an amino acid is polar or not, draw its structure and look for polar groups such as carbonyl or hydroxyl groups (e.g., Gln). Amino acids with mostly non-polar characteristics either lack heteroatoms in the side chain or their influence on polarity is small (e.g., Met). Keep in mind that the distinction between polar and nonpolar is not always clear-cut. Additionally, the pKa value is a useful indicator, as it can help you determine whether the amino acid is charged at neutral pH (e.g. Lys).


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