How to determine which group an amino acid belongs to Flashcards
Every amino acid has a carboxylic acid group, an amino group, an α-carbon, and an R group. Look at the R group to classify the amino acid.
Acidic R groups contain a carboxylic acid functional group, -COOH. Basic R groups contain an amino (not amide) functional group, -NH2, which attracts a proton to form -NH3. Neutral polar R groups are neither acidic nor basic, but they contain a highly electronegative atom such as oxygen, nitrogen, or sulfur. Neutral nonpolar R groups contain mostly carbon and hydrogen (alkyl groups). They may also contain nitrogen or sulfur, but the effect of those atoms is diminished due to the size of the alkyl portion.
You should also keep in mind the different behaviors of acids and bases: acids can donate H+ ions; bases can accept H+ ions.
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Acidic R groups contain a carboxylic acid functional group, -COOH.
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Basic R groups contain an amino (not amide) functional group, -NH2, which attracts a proton to form -NH3.
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Neutral polar R groups are neither acidic nor basic, but they contain a highly electronegative atom such as oxygen, nitrogen, or sulfur.
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Neutral nonpolar R groups contain mostly carbon and hydrogen (alkyl groups). They may also contain nitrogen or sulfur, but the effect of those atoms is diminished due to the size of the alkyl portion.
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Where do you look to determine the group of the amino acid?
the R group
What does an acidic amino acid always have?
a -COOH group
What does a basic amino acid always have?
an amine NH2; which attracts a proton to form NH3 group; NOT amide
What is the distinguishable characteristic of a neutral polar?
have highly electronegative atoms such as S (sulfur), O (oxygen), N (nitrogen)
What is the distinguishable characteristic of neutral non polar?
the R- group mainly contains alkyl group
- may also contain S or N group, however their effects can be diminished due to the size of the alkyl portion
true of false, acids donate protons?
true
true or false bases accept protons?
true
