Biochem Quiz 2

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40 Terms
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primary structure
describes the order of amino acids in a protein, held together by peptide bonds
what causes hydrogen bonds?
differences in electronegativity
planar peptide bonds rotate around the... a. beta carbon b. nitrogen c. alpha carbon d. carbonyl carbon
c. alpha carbon
secondary structure
describes the spatial arrangement or shape of the polypeptide backbone in a protein, held together by hydrogen bonds in the backbone
true or false: amino acids are read from the N-terminal to the C-terminal
where do the R-groups point in an alpha helix? a. in toward the center of the helix b. out away from the helix c up toward the top of the helix d. down toward the bottom of the helix
b. out away from the helix
every -------- amino acid is connected in an alpha helix. a. third b. fourth c. fifth d. sixth
b. fourth
true or false: alpha helices and beta sheets are a part of tertiary protein structure
false (secondary)
which amino acid doesn't like to be a part of a helix? a. glycine b. cysteine c. phenylalanine d. proline
d. proline (secondary amine)
what is the part of a protein that isn't an alpha helix or a beta sheet?
random coil
true or false: the R-groups in a beta sheet point out in alternating directions
which is not a feature of fibrous proteins? a. many helices b. very weak c. forms hydrophobic interactions
b. very weak (they are very strong)
which is not a feature of globular proteins? a. globe shaped b. hydrophobic core c. hydrophobic outside
c. hydrophobic outside (hydrophilic outside)
true or false: intermolecular means within the same molecule
false (intramolecular is within the same one, intermolecular is between 2 different molecules)
which is not associated with tertiary structure? a. hydrogen bonds b. ionic bonds c. peptide bonds d. hydrophobic interactions e. disulfide bonds
c. peptide bonds (primary)
what is a salt bridge? a. a momentary unequal distribution of electrons b. an ionic bond c. an interaction between acidic and basic amino acid residues d. a london dispersion force e. b and c f. a and b
e. b and c
true or false: a london dispersion force is a hydrophobic interaction
is a disulfide bond/disulfide bridge ionic or covalent?
tertiary structure
describes the overall 3D structure of a protein, held together by various forces between R-groups, the native state of a protein
true or false: a conjugated protein contains only amino acids
false (simple)
every protein will have every structure except for a. primary b. secondary c. tertiary d. quaternary
d. quaternary
quaternary structure
describes how two (or more) peptide chains interact to make a larger structure, held together by the same forces found in tertiary structure
which amino acid is the "alpha helix breaker"? a. proline b. glycine c. cysteine d. serine
a. proline
true or false: hydrolysis cleaves peptide bonds
which amino acid does chymotrypsin NOT cleave beside? a. tyrosine tyr b. tryptophan trp c. isoleucine ile d. phenylalanine phe
c. isoleucine (only aromatic a.a.s)
which amino acid does trypsin NOT cleave beside? a. histidine his b. glycine gly c. arginine arg d. lysine lys e. a and b
b. glycine (only basic a.a.s, including histidine)
true or false: chymotrypsin and trypsin cleave on the N-terminal side of the peptide bond
false (C-side terminal)
protein denaturation
loss of secondary, tertiary, and/or quaternary structure, caused by disruption of noncovalent and disulfide bonds
heat and detergents disrupt: a. salt bridges b. hydrogen bonds c. covalent bonds d. hydrophobic interactions
d. hydrophobic interactions
pH changes disrupt: a. salt bridges b. hydrogen bonding c. covalent bonds d. hydrophobic interactions
a. salt bridges (changing charges of acidic/basic R-groups)
inorganic salts disrupt: a. salt bridges b. hydrogen bonding c. covalent bonding d. hydrophobic interactions
a. salt bridges (competition for ionic bonding sites)
organic compounds disrupt: a. salt bridges b. hydrogen bonding c. covalent bonding d. hydrophobic interactions
b. hydrogen bonding
mechanical forces disrupt: a. salt bridges b. hydrogen bonding c. covalent bonding d. hydrophobic interactions
c. covalent bonding (/multiple forces)
what is a conformational change?
a change in shape from native state to new misfolded structure
what is a prion?
proteinaceous infectious particle, a protein becomes a disease, Creutz-Jakob disease / Kuru in humans
will an enzyme decrease or increase the amount of energy needed for a reaction to occur?
which is not a general characteristic of enzymes? a. globular in shape b. nonspecific c. water soluble d. none of the above
b. nonspecific
what is the catalytic triad?
3 specific amino acid residues on the substrate
where does the substrate bond to the enzyme? a. anywhere b. in the core of the enzyme c. the active site d. the most electronegative side
c. the active site
true or false: enzymatic reactions are reversible