BCH403 EXAM | LATEST 2024|2025
UPDATE | QUESTIONS AND
ANSWERS
Protein - Answer-linear polymer of L-a-amino acids linked to one another by peptide
bonds
Primary - Answer-linear
Secondary - Answer-spatial, stabilized by h-bond
Tertiary - Answer-Folding of secondary units, minimize volume
Quaternary - Answer-multiple individual polypeptide chains in multi subunit protein
complex
H-bond stabilizing secondary structure - Answer-between amide H's and carbonyl
oxygens
a-Helix - Answer-• Right handed "corkscrew"
One turn every 0.54 nm = 3.6 residues / turn; 0.15 nm per residue
H-bonds stabilize between - Answer-carbonyl oxygen of residue n and the
amidehydrogen of residue n + 4
Disrups a-Helix - Answer-Proline
Help predict tertiary structure - Answer-a-helix
b-Sheets - Answer--More extended structure than the a-helix
-H-bonding exists between adjacent b-strands
-Alternate side chains point in opposite directions
-b-sheets may have parallel or antiparallel orientation
b-turns - Answer-• Compact turn; allows for abruptreversal (180o) in direction of the
polypeptide chain within 4 amino acid residues.
• Stabilized by a hydrogen bond between residues n and n + 3
• Proline often found at position 2, glycine at position 3 (X-P-G-)
• Turns are often at "edges" of globular proteins; allows for a change in the direction of
the polypeptide chain
UPDATE | QUESTIONS AND
ANSWERS
Protein - Answer-linear polymer of L-a-amino acids linked to one another by peptide
bonds
Primary - Answer-linear
Secondary - Answer-spatial, stabilized by h-bond
Tertiary - Answer-Folding of secondary units, minimize volume
Quaternary - Answer-multiple individual polypeptide chains in multi subunit protein
complex
H-bond stabilizing secondary structure - Answer-between amide H's and carbonyl
oxygens
a-Helix - Answer-• Right handed "corkscrew"
One turn every 0.54 nm = 3.6 residues / turn; 0.15 nm per residue
H-bonds stabilize between - Answer-carbonyl oxygen of residue n and the
amidehydrogen of residue n + 4
Disrups a-Helix - Answer-Proline
Help predict tertiary structure - Answer-a-helix
b-Sheets - Answer--More extended structure than the a-helix
-H-bonding exists between adjacent b-strands
-Alternate side chains point in opposite directions
-b-sheets may have parallel or antiparallel orientation
b-turns - Answer-• Compact turn; allows for abruptreversal (180o) in direction of the
polypeptide chain within 4 amino acid residues.
• Stabilized by a hydrogen bond between residues n and n + 3
• Proline often found at position 2, glycine at position 3 (X-P-G-)
• Turns are often at "edges" of globular proteins; allows for a change in the direction of
the polypeptide chain
