The Three-Dimensional Structure of Proteins Flashcards
Cys-Ala-Gly-Arg-Gln-Met
The amino terminal amino acid is:
a. Arg
b. Cys
c. Gln
d. Met
e. None of these.
b
Cys-Ala-Gly-Arg-Gln-Met
The carboxyl terminal end is:
a. Arg
b. Cys
c. Gln
d. Met
e. None of these.
d
Cys-Ala-Gly-Arg-Gln-Met
The overall, net ionic charge on this peptide at pH = 7 would be:
a. +2
b. +1
c. 0
d. −1
e. −2
b
The sequence of monomers in any polymer is this type of structure:
a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure
e. All of these
a
Hydrogen bonds are most important in this type of structure in proteins:
a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure
e. All of these
b
The overall folding of a single protein subunit is called:
a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure
c
The location of prosthetic groups is shown in this level of structure:
a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure
e. All of these
c
Structures which repeat over and over in secondary structure are called:
a. primary structure
b. domain
c. supersecondary structure
d. prosthetic group
e. All of these
c
Covalent bonds are important in all these structures, except:
a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure
e. All of these
d
Disulfide bonds are most important in this type of structure:
a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure
e. All of these
c
Which of the following forces are involved in maintaining the primary structure of a protein?
a. covalent bonds
b. hydrogen bonds
c. ionic interactions
d. hydrophobic interactions
a
Which of the following amino acid substitutions would be least likely to have a deleterious effect on protein function?
a. His changes to Asp
b. Leu changes to Ile
c. Glu changes to Gln
d. Trp changes to Gly
b
A single amino substitution can give rise to a malfunctioning protein.
a. True
b. False
a
Assuming the oligopeptide ALPHAHELICKS forms one continuous α-helix, the carbonyl oxygen of the glutamic acid
residue is hydrogen bonded to the amide nitrogen of
a. leucine.
b. isoleucine.
c. cysteine.
d. lysine.
e. serine.
c
What happens when a protein is denatured?
a. Its secondary structure is disrupted but its primary structure remains intact.
b. Its primary structure is disrupted but its secondary structure remains intact.
c. It is broken apart into its constituent amino acids.
d. It becomes all α-helix.
a
Which of the following best defines a domain?
a. A supersecondary region, often shared by proteins, that has a specific function.
b. A repetitive supersecondary structure.
c. A double-layered arrangement formed so that the polar groups face the aqueous environment, while the
nonpolar regions are kept away from the aqueous environment.
d. An unfolded region of a protein.
a
Which of the following amino acids is unlikely to be found in an α-helix?
a. phenylalanine
b. tryptophan
c. proline
d. lysine
c
Which of the following statements regarding hydrogen bonding in secondary structures is true?
a. Both α-helices and β-sheets only use intrachain hydrogen bonds.
b. Both α-helices and β-sheets only use interchain hydrogen bonds.
c. α-helices only use intrachain hydrogen bonds and β-sheets can use either intrachain or interchain hydrogen
bonds.
d. α-helices can use either intrachain or interchain hydrogen bonds and β-sheets only use interchain hydrogen
bonds.
c
Which of the following factors tend to destabilize α-helices?
a. clusters of amino acids with bulky R-groups
b. clusters of amino acids with similarly charged R-groups
c. Both of these.
d. Neither of these
c
Which of the following best describes the structure of collagen?
a. It is composed of a single α-helix.
b. It is a double helix.
c. It is a triple helix
d. It is composed primarily of β-sheet.
c
Which of the following is true?
a. The peptide bonds in the β-sheet are extended.
b. The peptide bonds in the α-helix coil back on themselves.
c. Both α-helices and β-sheets can be found as part of tertiary structure.
d. All of these
d
Which of the following is often found connecting the strands of an antiparallel β-sheet?
a. β-bulge
b. reverse turn
c. α-helix
d. prosthetic group
b
Which of the following best describes a motif?
a. a repetitive supersecondary structure
b. a common nonrepetitive irregularity found in antiparallel β-sheets
c. a protein conformation with biological activity
d. a group of atoms other than an amino acid
a
In the β-pleated sheet conformation
a. there are hydrogen bonds perpendicular to the direction of the polypeptide chain.
b. the polypeptide chain is almost fully extended.
c. the polypeptide chains may be hydrogen bonded together in a parallel or antiparallel orientation.
d. all of these
d
Which of the following is the most common function for fibrous proteins?
a. enzymes
b. structural roles.
c. carrier molecules.
d. enzymes and carrier molecules.
e. All of these.
b
In the α-helix
a. there are no hydrogen bonds
b. the peptide chain is fully extended
c. the peptide chain bends back on itself
d. there are hydrogen bonds parallel to the helix axis
d
Which one is not an example of supersecondary structure?
a. the pyrrole ring
b. the Greek key
c. the β-meander
d. the β-barrel
a
Which of the following is true?
a. The collagen helix and the α-helix are the only types of helices in proteins.
b. Globular proteins tend to be water soluble
c. Globular and fibrous are examples of secondary structure
d. All of these
b
As an animal ages, the amount of cross-linking of collagen in tissue
a. tends to decrease.
b. tends to increase.
c. tends to remain unchanged.
b
Vitamin C (ascorbic acid) prevents scurvy because
a. it is involved in the formation of the proper β-sheet structure of collagen.
b. it is involved in the metabolism of heme used in hemoglobin.
c. it encourages the formation of disulfide linkages in collagen.
d. it is an unusual amino acid found in the primary structure of collagen.
e. it is used to hydroxylate prolines in the primary structure of collagen.
e
The following is true about the hydroxyproline in collagen:
a. Hydroxyproline is incorporated into the chain during polymerization of amino acids.
b. Vitamin C is necessary for the synthesis of hydroxyproline.
c. Hydroxyproline is important in holding the 3 strands of collagen together.
d. Hydroxyproline requires Vitamin C for its synthesis and it holds the collagen helix together.
e. All of these.
d
Which of the following is true about the alpha helix?
a. the structure is stablized by hydrogen bonds
b. there are 3.6 residues for every turn of the helix
c. the pitch of the helix is 5.4 angsroms
d. all of the choices
d
Fibrous proteins
a. are always composed of helical structures.
b. are always composed of β-sheets.
c. can be composed of either helical or β-sheet structures.
d. are always water soluble
c
