Amino Acid Classifications Practice Problems

Draw the fully ionized form of the amino acids given: isoleucine (nonpolar side chain) and threonine (polar side chain). Give the reason for the difference in their side chain polarity.

Which is hydrophilic among the given amino acids? 

i. alanine 

ii. glutamic acid 

iii. arginine

Cell membrane proteins arbitrate the processes that are fundamental for cells. Spanning the entire membrane are called transmembrane proteins, which are involved in the transport of molecules across the membrane into the cell. The fluids inside and outside of the cell are water-based, while the interior of the cell membrane is nonpolar. Which set of amino acids below is expected to be found in the part of a transmembrane protein that lies within the cell membrane interior?

Identify whether histidine is hydrophilic or hydrophobic.

What do serine, tyrosine, cysteine, and glutamine have in common? Is it expected to find these amino acids on the interior or on the exterior of a globular protein?

Which of the amino acids below is most likely to be found on the exterior of a water-soluble protein, and which of them is more likely to be found on the interior?

i. tryptophan 

ii. threonine 

iii. lysine 

iv. glutamic acid

Consider the pairs of amino acids below:

A. alanine and valine

B. leucine and isoleucine

C. glycine and phenylalanine

D. serine and threonine

i. Which pair have side chains capable of hydrogen bonding?

ii. Draw each structure hydrogen bonding to one another.

iii. Sketch each structure hydrogen bonding to water.