All amino acids (choose the correct choice)
a) have the same side chains
b) form zwitterions
c) have the same isoelectric points
d) show hydrophobic tendencies
e) are essential amino acids
Is it b)?
Yes, b is correct.
The correct choice is b) form zwitterions.
To determine the correct answer, we need to have a basic understanding of amino acids and their properties. Amino acids are the building blocks of proteins and are characterized by having an amino group (-NH2), a carboxyl group (-COOH), and a variable side chain (R group) attached to a central carbon atom called the α-carbon.
Option a) states that all amino acids have the same side chains, which is incorrect. Amino acids have different side chains, which can vary in size, shape, and chemical properties. These side chains determine the unique chemical characteristics of each amino acid and play a crucial role in protein structure and function.
Option c) suggests that all amino acids have the same isoelectric points, which is also incorrect. The isoelectric point (pI) of an amino acid is the pH at which it is electrically neutral, with an equal number of positive and negative charges. The pI varies for different amino acids due to differences in their ionizable groups.
Option d) suggests that all amino acids show hydrophobic tendencies, which is not accurate either. Some amino acids have hydrophilic (water-loving) side chains, while others possess hydrophobic (water-repelling) side chains. The presence of both hydrophilic and hydrophobic amino acids allows proteins to adopt specific structures and interact with their surroundings.
Option e) states that all amino acids are essential amino acids, which is incorrect. Essential amino acids are a specific set of amino acids that cannot be synthesized by our bodies and must be obtained from our diet. These essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Therefore, the correct choice is b) form zwitterions. Amino acids can exist as zwitterions, which are electrically neutral molecules with both a positive and negative charge. This occurs due to the presence of the amino group with a positive charge and the carboxyl group with a negative charge, both coexisting within the same molecule.