BMSC 200 - Module 4 Exam
Questions with Complete Answers
Keratin purpose and structure - ANSWER-Protein of hair, nails, and horns. It is
defined by a pseudo-seven repeat at the primary structure in which positions a and d
are occupied by non-polar hydrophobic residues.
Keratin polypeptides - ANSWER-Form amphipathic alpha-helicies and these helicies
wrap around each other in a left-handed fashion to the formation of coiled-coils.
How are keratin polypeptides stabilized? - ANSWER-These subunits of keratin are
stabilized and strenghted from cysteine residues resulting in disulfide bonds. The
strenght/ rigidity of keratin depends on the cystein content.
Collagen - ANSWER-A major protein of vertabrates (25%). It's basic job is to hold
things together
Collagen purpose and primary structure - ANSWER-The primary structural protein
within the body. It is defined by a triplet repeat of (Gly-X-Y) at the level of primary
structure where X and Y are often proline or hydroxyproline
Collagen Polypeptides - ANSWER-Form left-handed helicies and three of these
helicies wrap around each other in a right-handed coiled coil.
Collagen Secondary Structure - ANSWER-Forms left-handed helices (but are zig-
zag shaped at proline) of three residues/turn
Quaternary Structure of Collagen - ANSWER-Forms coiled coils. Three left-handed
helicies wrap around each other in a right handed fashion
Tertiary Structure of Collagen - ANSWER-Nearly the full lenght of the polypeptide is
helical
How are collagen polypeptides stabilized? - ANSWER-These subunits are stabilized
through covalent linkages involving residues which undergo oVitamin-C dependent
post-translation modifications.
Silk purpose and primary structure - ANSWER-The protein of cocoons and
spiderwebs. Is defined by a repeating pattern of Gly-Ser-Gly-Ala-Gly-Ala.
Silk - ANSWER-Produced by insects and spiders for formation of webs and cocoons
which are both strong and flexible.
Secondary Structure of silk - ANSWER-Made primarily of beta-sheets. The fully
, extended polypeptides of the beta strands offer considerable strength. Silk has very
high strength yet is still highly flexible.
How are silk polypeptides stabilized? - ANSWER-Silk involved formation of beta
sheets in which the structure is stabilized through non-covalent interactions from the
alanies and glycines (zipper) in two dimensions and covalent linkages offered by the
fully extended polypeptide chains in the third dimension.
Three dimensions of silk - ANSWER-1) Fully extended polypeptide chains (strength).
2) Association of strands by hydrogen bonding (non-covalent) (flexible).
3) Association of sheets by van der Waals and hydrophobic interactions
(flexible).
Native Conformation - ANSWER-The biologically active conformation of a
biomolecule; each protein folds into a single stable shape (physiiological conditions)
Hydrogen Bond - ANSWER-A weak electrostatic interaction between an
electronegative atom (such as oxygen or nitrogen) and a hydrogen covalently linked
to a second electronegative atom.
Ionic Interaction - ANSWER-Forces of attraction or repulsion between charged
groups of opposite, or same, charge respectively.
van der Waals Interaction - ANSWER-The attractive or repulsive forces between
molecules (or between parts of the same molecule) due to induced or transient
diploes.
Hydrophobic Interaction - ANSWER-The association of non-polar groups with each
other in aqueous system. A primary driving force of biomolecular structures.
Phi Angle - ANSWER-The torsion angle within a polypeptide chain linking the alpha
carbon to the amide nitrogen (mostly to left). There is theoretical freedom of rotation
about the phi angle from -180 to +180 degrees.
Psi Angle - ANSWER-The torsion angle within a polypeptide chain linking the alpha
carbon to the carbonyl carbon (mostly to right). There is theoretical freedom of
rotation about the phi angle from -180 to +180 degrees.
Ramachandran Plot - ANSWER-A graph representing all the conformations of phi
and psi on which specific values of phi and psi can be plotted for a polypeptide.
Reveals common structural motifs such as elements of secondary structure.
Alpha Helix - ANSWER-A helical conformation of a polypeptide chain, usually right-
handed, with maximal intrachain hydrogen-bonding.
Beta Sheet - ANSWER-An extended arrangement of a polypeptide chain. Beta
sheets are made up of beta strands which may be either parallel or antiparallel.
Helix Dipole - ANSWER-The uneven distribution of charge which forms over the
length of an alpha helix due to the differential electronegativities of the amide and
Questions with Complete Answers
Keratin purpose and structure - ANSWER-Protein of hair, nails, and horns. It is
defined by a pseudo-seven repeat at the primary structure in which positions a and d
are occupied by non-polar hydrophobic residues.
Keratin polypeptides - ANSWER-Form amphipathic alpha-helicies and these helicies
wrap around each other in a left-handed fashion to the formation of coiled-coils.
How are keratin polypeptides stabilized? - ANSWER-These subunits of keratin are
stabilized and strenghted from cysteine residues resulting in disulfide bonds. The
strenght/ rigidity of keratin depends on the cystein content.
Collagen - ANSWER-A major protein of vertabrates (25%). It's basic job is to hold
things together
Collagen purpose and primary structure - ANSWER-The primary structural protein
within the body. It is defined by a triplet repeat of (Gly-X-Y) at the level of primary
structure where X and Y are often proline or hydroxyproline
Collagen Polypeptides - ANSWER-Form left-handed helicies and three of these
helicies wrap around each other in a right-handed coiled coil.
Collagen Secondary Structure - ANSWER-Forms left-handed helices (but are zig-
zag shaped at proline) of three residues/turn
Quaternary Structure of Collagen - ANSWER-Forms coiled coils. Three left-handed
helicies wrap around each other in a right handed fashion
Tertiary Structure of Collagen - ANSWER-Nearly the full lenght of the polypeptide is
helical
How are collagen polypeptides stabilized? - ANSWER-These subunits are stabilized
through covalent linkages involving residues which undergo oVitamin-C dependent
post-translation modifications.
Silk purpose and primary structure - ANSWER-The protein of cocoons and
spiderwebs. Is defined by a repeating pattern of Gly-Ser-Gly-Ala-Gly-Ala.
Silk - ANSWER-Produced by insects and spiders for formation of webs and cocoons
which are both strong and flexible.
Secondary Structure of silk - ANSWER-Made primarily of beta-sheets. The fully
, extended polypeptides of the beta strands offer considerable strength. Silk has very
high strength yet is still highly flexible.
How are silk polypeptides stabilized? - ANSWER-Silk involved formation of beta
sheets in which the structure is stabilized through non-covalent interactions from the
alanies and glycines (zipper) in two dimensions and covalent linkages offered by the
fully extended polypeptide chains in the third dimension.
Three dimensions of silk - ANSWER-1) Fully extended polypeptide chains (strength).
2) Association of strands by hydrogen bonding (non-covalent) (flexible).
3) Association of sheets by van der Waals and hydrophobic interactions
(flexible).
Native Conformation - ANSWER-The biologically active conformation of a
biomolecule; each protein folds into a single stable shape (physiiological conditions)
Hydrogen Bond - ANSWER-A weak electrostatic interaction between an
electronegative atom (such as oxygen or nitrogen) and a hydrogen covalently linked
to a second electronegative atom.
Ionic Interaction - ANSWER-Forces of attraction or repulsion between charged
groups of opposite, or same, charge respectively.
van der Waals Interaction - ANSWER-The attractive or repulsive forces between
molecules (or between parts of the same molecule) due to induced or transient
diploes.
Hydrophobic Interaction - ANSWER-The association of non-polar groups with each
other in aqueous system. A primary driving force of biomolecular structures.
Phi Angle - ANSWER-The torsion angle within a polypeptide chain linking the alpha
carbon to the amide nitrogen (mostly to left). There is theoretical freedom of rotation
about the phi angle from -180 to +180 degrees.
Psi Angle - ANSWER-The torsion angle within a polypeptide chain linking the alpha
carbon to the carbonyl carbon (mostly to right). There is theoretical freedom of
rotation about the phi angle from -180 to +180 degrees.
Ramachandran Plot - ANSWER-A graph representing all the conformations of phi
and psi on which specific values of phi and psi can be plotted for a polypeptide.
Reveals common structural motifs such as elements of secondary structure.
Alpha Helix - ANSWER-A helical conformation of a polypeptide chain, usually right-
handed, with maximal intrachain hydrogen-bonding.
Beta Sheet - ANSWER-An extended arrangement of a polypeptide chain. Beta
sheets are made up of beta strands which may be either parallel or antiparallel.
Helix Dipole - ANSWER-The uneven distribution of charge which forms over the
length of an alpha helix due to the differential electronegativities of the amide and
