We can tell how an amino acid will be classified (as polar or non-polar) by look
ID: 32940 • Letter: W
Question
We can tell how an amino acid will be classified (as polar or non-polar) by looking at it to see whether? (select all that apply)
it has a hydrocarbon chain or ring in its R-group; this will make it insoluble in water (and thus non-polar).
it has an electronegative atom (like oxygen) in its carboxyl group; this will classify it as polar.
it has a charge (- or +) in its amino group; this will make it non-polar.
it has a charge (- or +) in its R-group; this will make it polar.
it has a hydrocarbon chain or ring in its R-group; this will make it insoluble in water (and thus non-polar).
it has an electronegative atom (like oxygen) in its carboxyl group; this will classify it as polar.
it has a charge (- or +) in its amino group; this will make it non-polar.
it has a charge (- or +) in its R-group; this will make it polar.
Explanation / Answer
it has a hydrocarbon chain or ring in its R-group; this will make it insoluble in water (and thus non-polar).
Principles of Polarity:
The greater the electronegativity difference between atoms in a bond, the more polar the bond. Partial negative charges are found on the most electronegative atoms, the others are partially positive. Review the polarity of functional groups.
Non-Polar Side Chains:
Side chains which have pure hydrocarbon alkyl groups (alkane branches) or aromatic (benzene rings) are non-polar. Examples include valine, alanine, leucine, isoleucine, phenylalanine.
The number of alkyl groups also influences the polarity. The more alkyl groups present, the more non-polar the amino acid will be. This effect makes valine more non-polar than alanine; leucine is more non-polar than valine.
Polar Side Chains:
Side chains which have various functional groups such as acids, amides, alcohols, and amines will impart a more polar character to the amino acid. The ranking of polarity will depend on the relative ranking of polarity for various functional groups as determined infunctional groups. In addition, the number of carbon-hydrogens in the alkane or aromatic portion of the side chain should be considered along with the functional group.
Example: Aspartic acid is more polar than serine because an acid functional group is more polar than an alcohol group.
Example: Serine is more polar than threonine since threonine has one more methyl group than serine. The methyl group gives a little more non-polar character to threonine.
Example: Serine is more polar than tyrosine, since tyrosine has the hydrocarbon benzene ring
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.