Tutorial:Basic Chemistry Topics: Difference between revisions

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'''Neutral, Polar vs. Nonpolar Amino Acids'''
'''Polar vs. Nonpolar Amino Acids'''
 
The polarity of an amino acid depends on the difference in electronegativity and the asymmetry of the compound's structure, discussed previously. For example, Arginine is a polar amino acid and Glycine is a nonpolar amino acid. Described earlier, an amino acid’s structure consists of a carboxylic acid, an amine, hydrogen, and a functional group. Look at the structure of <scene name='Tutorial:Basic_Chemistry_Topics/Polar_nonpolaraa/1'>arginine and glycine</scene>. Arginine has the amine group, carboxylic acid and hydrogen located towards the bottom of the representation, and the functional group is the large extension of atoms upward. You can see from this image that the functional group has a greater density/electronegativity compared to the core of the amino acid (carboxylic acid, amine and hydrogen), hence making this amino acid polar. In contrast the structure of glycine, located next to arginine, has little polarity. The functional group attached to glycine is only a methyl group (CH3). A methyl group has low density/electronegativity compared to the rest of the structure, making glycine a nonpolar amino acid. Neutral amino acids have functional groups that are similar in electronegativity compared to the core, so the electrons are not pulled in one direction more dominantly than another. In other words, there is no increase in density to one side. When an amino acid is neutral, it is less reactive than a polar amino acid. It is less reactive because the structure is stable. A polar amino acid is pulling electrons, yielding a slight positive and negative charge within the amino acid structure. This makes the compound less stable. The charges increase the molecules reactivity with other substances.


The polarity of an amino acid is dependent on the difference in electronegativity and the asymmetry of the compounds structure, discussed previously. For example, Arginine is a polar amino acid and Glycine is a nonpolar amino acid. As we learned earlier, an amino acid’s structure consists of a carboxylic acid, an amine, hydrogen, and a functional group. Look at the structure of <scene name='Tutorial:Basic_Chemistry_Topics/Polar_nonpolaraa/1'>arginine and glycine</scene>. Arginine has the amine group, carboxylic acid and hydrogen located towards the bottom of the representation, and the functional group is the large extension of atoms upward. You can see from this image that the functional group has a greater density/electronegativity compared to the core of the amino acid (carboxylic acid, amine and hydrogen), hence making this amino acid polar. In contrast the structure of glycine, located next to arginine, has little polarity. The functional group attached to glycine is only a methyl group (CH3). A methyl group has low density/electronegativity compared to the rest of the structure, making glycine a nonpolar amino acid. Neutral amino acids have functional groups that are similar in electronegativity compared to the core, so the electrons are not pulled in one direction more dominantly then another. In other words, there is no increase in density to one side. When an amino acid is neutral, it is less reactive then a polar amino acid. It is less reactive because the structure is stable. A polar amino acid is pulling electrons, yielding a slight positive and negative charge within the amino acid structure. This makes the compound less stable. Those charges want to react with other atoms, yielding the higher reactivity.


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