chapter 14
What is the strongest type of interaction between the side chains of an isoleucine amino acid and a phenylalanine amino acid in a protein? -disulfide bond -hydrogen bonding -electrostatic interactions -London dispersion forces
London dispersion forces
Which of the following is one of the characteristics of amino acids? -They are colorless solids. -They have low melting points. -They have an amorphous structure. -They are volatile compounds. -They are mostly odorless.
They are colorless solids.
The _______ s a location on an enzyme where a substrate binds and is transformed to a product.
active site
An _____ is a molecule that contains an amino group and a carboxyl group.
amino acid
Which amino acid is a basic amino acid? -arginine -cysteine -alanine -serine
arginine
The alpha helix is stabilized by intrachain hydrogen bonding between the ____________.
carbonyl oxygen atom of one amino acid and the amide hydrogen atom four amino acids up the chain
A(n) _____ is any substance that increases the rate or speed of a chemical reaction without being changed or consumed in the reaction. -indicator -catalyst -reactant -substrate -reagent
catalyst
_____ is the term used for any change in the three-dimensional structure of a protein that renders it incapable of performing its assigned function. -protein crystallization -fixation -putrefaction -mutation -denaturation
denaturation
unfolding of a protein is called -hydrolysis -renaturation -reduction -denaturation -oxidation
denaturation
Which of the following amino acids has a net negative charge at physiological pH? -alanine -lysine -asparagine -glutamate -histidine
glutamate
What is the N-terminal amino acid in the tetrapeptide glycylalanyisoleucylmethionine? -isoleucine -glycine -alanine -methionine
glycine
What type of attractive interactions results from electrostatic attractions between positively- and negatively-charged side chains of amino acids? -disulfide linkages -hydrophobic interactions -hydrogen bonding -dispersion forces -ionic bonding
ionic bonding
The particular pH at which a given amino acid exists in solution as a zwitterion is called the ______ -stoichiometric point -isoelectric point -isosbestic point -isoionic point -equivalence point
isoelectric point
Hair and the outer layer of skin are composed of
keratin
Which of the following amino acids carries a net positive charge physiological pH? -leucine -lysine -proline -isoleucine -valine
lysine
Valine, leucine, isoleucine, glycine, alanine, phenylalanine, tryptophan, methionine, and proline are amino acids that belong to which class? -aromatic R group -positively charged R group -negatively charged R group -polar but neutral R group -nonpolar R group
nonpolar R group
The primary structure of proteins is principally maintained by ________. -ionic bonds -hydrogen bonds -hydrophobic interactions -disulfide linkages -peptide bonds
peptide bonds
A polypeptide with a net positive charge at physiological pH most likely contains amino acids with R groups of what type? -negatively charged (acidic) -aromatic -polar but neutral -nonpolar -positively charged (basic)
positively charged (basic)
The sequence of amino acids in a polypeptide chain or protein is indicated by the _____. -primary structure -quinary structure -tertiary structure -secondary structure -quaternary structure
primary structure
________________ is a property of a protein that is least likely to be affected by changes in pH. -post-quaternary structure -tertiary structure -quaternary structure -secondary structure -primary structure
primary structure
The separate subunits of hemoglobin are hydrogen-bonded to form a level of structure called the ____ -quaternary structure -tertiary structure -primary structure -secondary structure -quinary structure
quaternary structure
The alpha helix is an example of which of the following structural levels of proteins? -post-quaternary structure -tertiary structure -quaternary structure -secondary structure -primary structure
secondary structure
Which of the following refers to the fixed arrangement of the polypeptide backbone? -quaternary structure -tertiary structure -primary structure -secondary structure -quinary structure
secondary structure
Which of the following common amino acids found in proteins is an aromatic amino acid? -tyrosine -valine -alanine -leucine -isoleucine
tyrosine
Which of the following refers to an electrically neutral compound that contains both negatively- and positively-charged groups? -zwitterion -anion -holon -bipolaron -cation
zwitterion
