BIL 255 ALL QUESTIONS AND ANSWERS SURE A+
✔✔A helix bonding/structure - ✔✔the N-H of every peptide bond is hydrogen-bonded to
the C=O of a neighboring peptide bond located four amino acids away in the same
chain.
can either be right or left. if turning clockwise its right
✔✔how can membrane protein cross the lipid bilayer and why - ✔✔a-helix
Backbone is hydrophilic → stabilized by internal H-bonds; hydrophobic side chains face
outward → interact with lipid tails.
✔✔b-sheets - ✔✔2 or more regions of the chain lying side by side and connected by H+
bonds
✔✔B-sheet structural features - ✔✔The amino acid side chains in each strand project
alternately above and below the plane of the sheet.
Form rigid structures
Can be anti-parallel or parallel
When the neighboring segments run in the same orientation (say, from the N-terminus
to the C-terminus), the structure forms a parallel β sheet; when they run in opposite
directions, the structure forms an antiparallel β sheet
✔✔B sheet function - ✔✔Can perform useful biological functions:
Cells specialized for secretion
for example, store peptide or protein hormones in membrane-enclosed transport
vesicles.
Can interact with membrane
✔✔What can misfolded proteins cause? - ✔✔amyloid structures that cause disease
, ✔✔Protein levels of organization - ✔✔PRIMARY= amino acids have a specific protein
chain, single polypeptide chain
SECONDARY= the amino acids within a chain can be twisted or folded, polypeptide that
is either alpha or beta
TERTIARY= the chain itself is folded, combination of alpha and beta. three-dimensional
conformation formed by an entire polypeptide chain
QUATERNARY= if a protein has more than one chain, each chain has a specific
arrangement in space, combination of numerous polypeptides
✔✔protein domains - ✔✔discrete structural units in a protein, often associated with a
particular function(s)
✔✔protein families - ✔✔a group of proteins that are structurally and functionally related
✔✔Filament proteins - ✔✔What the flagellar apparatus specificity is switched to when
FlhB undergoes autocleavage
✔✔actin filament - ✔✔abundant in eukaryotic cell, major filament in cytoskeleton
✔✔what do filament amd spherical shell form - ✔✔hollow tube
✔✔collagen fibrils - ✔✔Structures composed of collagen molecules aligned head to tail
in overlapping rows
✔✔What type of proteins are most enzymes? - ✔✔globular proteins
✔✔Where are fibrous proteins especially abundant in multicellular organisms? -
✔✔Outside the cell, in the extracellular matrix.
✔✔how do polypeptides stabilize - ✔✔covalent cross linkage
✔✔ligand - ✔✔A molecule that binds specifically to a protein
✔✔What allows a protein to bind selectively and with high affinity to a ligand - ✔✔weak,
non covalent bonds
Each individual noncovalent interaction is weak, so that effective binding requires many
such bonds to be formed simultaneously. This is possible only if the surface contours of
the ligand molecule fit very closely to the protein, matching it like a hand in a glove
✔✔what is the region of a protein that associates with a ligand called? - ✔✔binding site
✔✔A helix bonding/structure - ✔✔the N-H of every peptide bond is hydrogen-bonded to
the C=O of a neighboring peptide bond located four amino acids away in the same
chain.
can either be right or left. if turning clockwise its right
✔✔how can membrane protein cross the lipid bilayer and why - ✔✔a-helix
Backbone is hydrophilic → stabilized by internal H-bonds; hydrophobic side chains face
outward → interact with lipid tails.
✔✔b-sheets - ✔✔2 or more regions of the chain lying side by side and connected by H+
bonds
✔✔B-sheet structural features - ✔✔The amino acid side chains in each strand project
alternately above and below the plane of the sheet.
Form rigid structures
Can be anti-parallel or parallel
When the neighboring segments run in the same orientation (say, from the N-terminus
to the C-terminus), the structure forms a parallel β sheet; when they run in opposite
directions, the structure forms an antiparallel β sheet
✔✔B sheet function - ✔✔Can perform useful biological functions:
Cells specialized for secretion
for example, store peptide or protein hormones in membrane-enclosed transport
vesicles.
Can interact with membrane
✔✔What can misfolded proteins cause? - ✔✔amyloid structures that cause disease
, ✔✔Protein levels of organization - ✔✔PRIMARY= amino acids have a specific protein
chain, single polypeptide chain
SECONDARY= the amino acids within a chain can be twisted or folded, polypeptide that
is either alpha or beta
TERTIARY= the chain itself is folded, combination of alpha and beta. three-dimensional
conformation formed by an entire polypeptide chain
QUATERNARY= if a protein has more than one chain, each chain has a specific
arrangement in space, combination of numerous polypeptides
✔✔protein domains - ✔✔discrete structural units in a protein, often associated with a
particular function(s)
✔✔protein families - ✔✔a group of proteins that are structurally and functionally related
✔✔Filament proteins - ✔✔What the flagellar apparatus specificity is switched to when
FlhB undergoes autocleavage
✔✔actin filament - ✔✔abundant in eukaryotic cell, major filament in cytoskeleton
✔✔what do filament amd spherical shell form - ✔✔hollow tube
✔✔collagen fibrils - ✔✔Structures composed of collagen molecules aligned head to tail
in overlapping rows
✔✔What type of proteins are most enzymes? - ✔✔globular proteins
✔✔Where are fibrous proteins especially abundant in multicellular organisms? -
✔✔Outside the cell, in the extracellular matrix.
✔✔how do polypeptides stabilize - ✔✔covalent cross linkage
✔✔ligand - ✔✔A molecule that binds specifically to a protein
✔✔What allows a protein to bind selectively and with high affinity to a ligand - ✔✔weak,
non covalent bonds
Each individual noncovalent interaction is weak, so that effective binding requires many
such bonds to be formed simultaneously. This is possible only if the surface contours of
the ligand molecule fit very closely to the protein, matching it like a hand in a glove
✔✔what is the region of a protein that associates with a ligand called? - ✔✔binding site
