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UMN BIOC 3021 Exam 2 Questions and
Answers
Proteins that can be classified according to the type and arrangement of secondary structure -
Answers✓✓(a) Antiparallel α-helix proteins
(b) Parallel or mixed β-sheet proteins
(c) Antiparallel β-sheet proteins
(d) Metal- and disulfide-rich proteins
Protein Domains or Modules - Answers✓✓amino acid sequences
that are used repeatedly in the same protein or that are
found in different proteins
How many proteins domains? - Answers✓✓40-100
Step 1 of Protein Folding - Answers✓✓A newly synthesized polypeptide first forms segments
of secondary structure (α-helix and β-sheet)
step 2 of protein folding - Answers✓✓These coalesce into a globular structure, primarily
through hydrophobic interactions
Step 3 of protein folding - Answers✓✓The final stable tertiary structure is generated by small
adjustments to the folded structure
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Step 4 of protein folding - Answers✓✓In the cell, protein folding may require the assistance of
molecular chaperones
quaternary Structure - Answers✓✓refers to the association of protein subunits to
form multi-subunit complexes
Monolayers and Micelles - Answers✓✓produced by amphipathic lipid molecules
interacting with water
Micelles - Answers✓✓lipid aggregates which have the hydrophobic tails in the
center and polar head groups facing outward
Bilayers - Answers✓✓produced spontaneously by certain lipids, particularly
phospholipids, instead of micelles
Bilayers - Answers✓✓Normally wrap around themselves to form closed vesicles, which
can consist of multiple bilayers.
Liposomes - Answers✓✓Vesicles with a single lipid bilayer
Liposomes - Answers✓✓Can be used as drug or enzyme delivery systems in
therapeutic applications.
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the phospholipid bilayer - Answers✓✓fluid supporting matrix for
membrane proteins, and both lipids and proteins are capable of
lateral and transverse movement.
Peripheral membrane proteins - Answers✓✓external to the lipid bilayer
Integral membrane proteins - Answers✓✓extend into or through the lipid bilayer
Lipid-Anchored Membrane Proteins - Answers✓✓Membrane proteins are covalently linked to
lipid molecules.
Peptidoglycan - Answers✓✓the strong, protective peptide/
polysaccharide layer of bacterial cell walls
Gram-negative bacteria - Answers✓✓have the peptidoglycan layer
between two lipid bilayers
Gram-positive bacteria - Answers✓✓have a thicker peptidoglycan layer external to a
single lipid bilayer.
Glycoproteins - Answers✓✓on the cell surface
Proteoglycans - Answers✓✓in the extracellular matrix