BMSC 200 Quiz 4 with Complete
Answers
secondary structure - ANSWER-localized interactions within a polypeptide
tertiary structure - ANSWER-final folding pattern of a single polypeptide
quaternary structure - ANSWER-folding pattern when multiple polypeptides are
involved
N, C - ANSWER-Primary structure is presented from the ? (amino) terminus to the ?
(carboxyl) terminus.
corresponding gene - ANSWER-primary structure is often determined through
investigation of the
amide, carboxyl - ANSWER-secondary structure maintained by hydrogen bonds
between main-chain ? and ? groups.
Viable forms of secondary structure must - ANSWER-1. Optimize the hydrogen
bonding potential of main-chain carbonyl and amide groups
2. Represent a favoured conformation of the polypeptide chain
donor, acceptor, equal, optimizing - ANSWER-• Each peptide bond has a hydrogen
bond ? and ? group.
• ? number of hydrogen bond donors and acceptors within the polypeptide main-
chain.
• This is important for ? hydrogen bonds.
Phi (Φ) Cα-N and Psi (ψ) Cα-C - ANSWER-Each α-carbon is held within the main-
chain through single bonds, about which there is complete freedom of rotation.
These bonds are
steric interference - ANSWER-When two atoms are brought close together such that
their electron clouds overlap, repulsive forces act to drive the atoms apart. This
influences the conformations that a molecule can adopt.
Ramachandran plot - ANSWER-Illustrates the possible combinations of phi and psi
Linus Pauling - ANSWER-Discovered the alpha helix structure of proteins
Alpha (α) Helix - ANSWER-- Right-handed helix with 3.6 residues/turn.
- Stabilized by hydrogen bonds parallel to axis of helix.
- Carbonyl groups point toward C-terminus; amide groups to the N-terminus.
, - Each carbonyl of residue n hydrogen bonds with amide group of residue n+4.
proline, glycine - ANSWER-because of the rigidity of ? and flexibility of ?, these
amino acids are not common in α-helicies
Val, Thr, Ile - ANSWER-Amino acids with side chain branches are less common in α-
helicies due to steric interference.
Ser, Asp, Asn - ANSWER-Amino acids with hydrogen bonding groups near the main-
chain are also less common in alpha helices
ion pairs - ANSWER-Charged residues tend to be positioned to form favourable ??
(residues of opposite charge separated by 3-4 positions).
positive - ANSWER-N terminus has partial ? dipole charge
negative - ANSWER-C terminus has partial ?dipole charge
oppose - ANSWER-Dipole is stabilized by residues at each termini whose charge ?
the helix dipole.
- Negatively charged residues (Asp, Glu) at the N terminus
- Positively charged residues (Lys, Arg, His) at the C terminus
3-4, 2 - ANSWER-Residues separated by ? positions in the primary sequence will be
on the same side of an ⍺- helix, whereas residues separated by ? positions in the
primary structure will be on opposite sides of the helix.
amphipathic helix - ANSWER-Positioning of hydrophobic and hydrophilic residues
within the primary structure generates an ?? with polar and non-polar faces.
Beta (β) sheets - ANSWER-4-5 β strands arranged side-by-side
- conformation = fully extended polypeptide chain
C=O, -NH - ANSWER-- hydrogen bonding in beta sheets is ? and ? bonds on
adjacent strands
parallel - ANSWER-In ? b sheets, strands run in same direction.
antiparallel - ANSWER-In ? b sheets, strands run in opposite direction, which makes
them more stable due to better geometry hydrogen bonding
mixed - ANSWER-b sheets that contain both parallel and antiparallel b strands
amphipathic beta sheet - ANSWER-- Side chains tend to alternate above and below
the polypeptide chain.
- Alternating polar and non-polar residues within the primary structure of a beta sheet
will result in an
final folding pattern - ANSWER-Tertiary structure represents the ??? of a single
polypeptide.
Answers
secondary structure - ANSWER-localized interactions within a polypeptide
tertiary structure - ANSWER-final folding pattern of a single polypeptide
quaternary structure - ANSWER-folding pattern when multiple polypeptides are
involved
N, C - ANSWER-Primary structure is presented from the ? (amino) terminus to the ?
(carboxyl) terminus.
corresponding gene - ANSWER-primary structure is often determined through
investigation of the
amide, carboxyl - ANSWER-secondary structure maintained by hydrogen bonds
between main-chain ? and ? groups.
Viable forms of secondary structure must - ANSWER-1. Optimize the hydrogen
bonding potential of main-chain carbonyl and amide groups
2. Represent a favoured conformation of the polypeptide chain
donor, acceptor, equal, optimizing - ANSWER-• Each peptide bond has a hydrogen
bond ? and ? group.
• ? number of hydrogen bond donors and acceptors within the polypeptide main-
chain.
• This is important for ? hydrogen bonds.
Phi (Φ) Cα-N and Psi (ψ) Cα-C - ANSWER-Each α-carbon is held within the main-
chain through single bonds, about which there is complete freedom of rotation.
These bonds are
steric interference - ANSWER-When two atoms are brought close together such that
their electron clouds overlap, repulsive forces act to drive the atoms apart. This
influences the conformations that a molecule can adopt.
Ramachandran plot - ANSWER-Illustrates the possible combinations of phi and psi
Linus Pauling - ANSWER-Discovered the alpha helix structure of proteins
Alpha (α) Helix - ANSWER-- Right-handed helix with 3.6 residues/turn.
- Stabilized by hydrogen bonds parallel to axis of helix.
- Carbonyl groups point toward C-terminus; amide groups to the N-terminus.
, - Each carbonyl of residue n hydrogen bonds with amide group of residue n+4.
proline, glycine - ANSWER-because of the rigidity of ? and flexibility of ?, these
amino acids are not common in α-helicies
Val, Thr, Ile - ANSWER-Amino acids with side chain branches are less common in α-
helicies due to steric interference.
Ser, Asp, Asn - ANSWER-Amino acids with hydrogen bonding groups near the main-
chain are also less common in alpha helices
ion pairs - ANSWER-Charged residues tend to be positioned to form favourable ??
(residues of opposite charge separated by 3-4 positions).
positive - ANSWER-N terminus has partial ? dipole charge
negative - ANSWER-C terminus has partial ?dipole charge
oppose - ANSWER-Dipole is stabilized by residues at each termini whose charge ?
the helix dipole.
- Negatively charged residues (Asp, Glu) at the N terminus
- Positively charged residues (Lys, Arg, His) at the C terminus
3-4, 2 - ANSWER-Residues separated by ? positions in the primary sequence will be
on the same side of an ⍺- helix, whereas residues separated by ? positions in the
primary structure will be on opposite sides of the helix.
amphipathic helix - ANSWER-Positioning of hydrophobic and hydrophilic residues
within the primary structure generates an ?? with polar and non-polar faces.
Beta (β) sheets - ANSWER-4-5 β strands arranged side-by-side
- conformation = fully extended polypeptide chain
C=O, -NH - ANSWER-- hydrogen bonding in beta sheets is ? and ? bonds on
adjacent strands
parallel - ANSWER-In ? b sheets, strands run in same direction.
antiparallel - ANSWER-In ? b sheets, strands run in opposite direction, which makes
them more stable due to better geometry hydrogen bonding
mixed - ANSWER-b sheets that contain both parallel and antiparallel b strands
amphipathic beta sheet - ANSWER-- Side chains tend to alternate above and below
the polypeptide chain.
- Alternating polar and non-polar residues within the primary structure of a beta sheet
will result in an
final folding pattern - ANSWER-Tertiary structure represents the ??? of a single
polypeptide.
