PORTAGE LEARNING BIOCHEM MODULE 3
FINAL PAPER 2026 FULL SOLUTION
QUESTIONS AND ANSWERS 100% CORRECT
◉ Name the 7 nonpolar, aliphatic amino acids in abbreviations.
Answer: Gly, Ala, Val, Pro, Leu, Ile, Met
◉ Describe aliphatic amino acids and their location in proteins.
Answer: Relatively small which allows them to interact with other
groups, found in interior of protein away from water with other
aliphatic groups (fold together)
◉ Why is proline unique?.
Answer: its side chain makes a ring by bonding with its main chain
nitrogen
◉ How do non-polar aromatic groups compare to aliphatic? (5
reasons).
Answer: similar to aliphatic in that they are non-polar, but the side
chains of these compounds contain a ring of carbons as an aromatic
functional group, not as small as the aliphatic, but they are more
rigid, aromatic ring structures have unique physical and chemical
properties
,◉ Why are the benzene rings important in aromatic groups?.
Answer: The double bonds (conjugated system) absorb light well for
proteins
◉ Name the 3 non-polar aromatic groups.
Answer: Phenylalanine (Phe,F), Tryptophan (Trp,W), Tyrosine
(Tyr,Y)
◉ Describe the polar neutral amino acids and location in proteins.
Answer: side chains that have a dipole, and most can hydrogen bond,
permits these amino acids to interact strongly with water, found on
the outside of the protein and in contact with water
◉ Name the 5 polar neutral amino acids.
Answer: Serine (Ser, S), Threonine (Thr, T), Cysteine (Cys, C),
Asparagine (Asn, N), Glutamine (Gln, Q)
◉ Describe the acidic amino acids.
Answer: side chains with pKa values smaller than 7, which indicates
they lose their proton in the acidic pH range, at physiological pH
(7.4) that these amino acids are negatively charged
◉ Name the 2 acidic amino acids.
, Answer: aspartic acid (Asp, D), glutamic acid (Glu, E)
◉ Describe basic amino acids.
Answer: pKa that is near or greater than pH = 7, which means their
side chains are normally positively charged, found in contact with
water because they hydrogen bond, located near acidic residues in
proteins to take advantage of favorable interactions between
positive and negative charges
◉ Name the 3 basic amino acids.
Answer: lysine (Lys, K), arginine (Arg, R), histidine (His, H)
◉ Why is Histidine unique?.
Answer: Does not have a charged group on its side chain, but can be
charged under certain circumstances, also has lower pKa of 6
◉ Why is Cysteine unique?.
Answer: its side chain is uncharged, but two cysteines can react
together and can form a disulfide bond by their sulfur atoms which
forms a covalent bond
◉ What are the functions of disulfide bonds? Where are they found?.
Answer: Stabilize a protein structure when present, found in
proteins that exist outside of the cell (keratin in hair)
FINAL PAPER 2026 FULL SOLUTION
QUESTIONS AND ANSWERS 100% CORRECT
◉ Name the 7 nonpolar, aliphatic amino acids in abbreviations.
Answer: Gly, Ala, Val, Pro, Leu, Ile, Met
◉ Describe aliphatic amino acids and their location in proteins.
Answer: Relatively small which allows them to interact with other
groups, found in interior of protein away from water with other
aliphatic groups (fold together)
◉ Why is proline unique?.
Answer: its side chain makes a ring by bonding with its main chain
nitrogen
◉ How do non-polar aromatic groups compare to aliphatic? (5
reasons).
Answer: similar to aliphatic in that they are non-polar, but the side
chains of these compounds contain a ring of carbons as an aromatic
functional group, not as small as the aliphatic, but they are more
rigid, aromatic ring structures have unique physical and chemical
properties
,◉ Why are the benzene rings important in aromatic groups?.
Answer: The double bonds (conjugated system) absorb light well for
proteins
◉ Name the 3 non-polar aromatic groups.
Answer: Phenylalanine (Phe,F), Tryptophan (Trp,W), Tyrosine
(Tyr,Y)
◉ Describe the polar neutral amino acids and location in proteins.
Answer: side chains that have a dipole, and most can hydrogen bond,
permits these amino acids to interact strongly with water, found on
the outside of the protein and in contact with water
◉ Name the 5 polar neutral amino acids.
Answer: Serine (Ser, S), Threonine (Thr, T), Cysteine (Cys, C),
Asparagine (Asn, N), Glutamine (Gln, Q)
◉ Describe the acidic amino acids.
Answer: side chains with pKa values smaller than 7, which indicates
they lose their proton in the acidic pH range, at physiological pH
(7.4) that these amino acids are negatively charged
◉ Name the 2 acidic amino acids.
, Answer: aspartic acid (Asp, D), glutamic acid (Glu, E)
◉ Describe basic amino acids.
Answer: pKa that is near or greater than pH = 7, which means their
side chains are normally positively charged, found in contact with
water because they hydrogen bond, located near acidic residues in
proteins to take advantage of favorable interactions between
positive and negative charges
◉ Name the 3 basic amino acids.
Answer: lysine (Lys, K), arginine (Arg, R), histidine (His, H)
◉ Why is Histidine unique?.
Answer: Does not have a charged group on its side chain, but can be
charged under certain circumstances, also has lower pKa of 6
◉ Why is Cysteine unique?.
Answer: its side chain is uncharged, but two cysteines can react
together and can form a disulfide bond by their sulfur atoms which
forms a covalent bond
◉ What are the functions of disulfide bonds? Where are they found?.
Answer: Stabilize a protein structure when present, found in
proteins that exist outside of the cell (keratin in hair)
