Chapter 4 - Biochemistry

chichi's version from 2017-03-03 03:34

Section 1

Question Answer
Are peptide bonds considered "weak" interaction in proteins?No
In an aqueous solution, protein conformation is determined by two major factos. One is the formation of the maximum number of hydrogen bonds. The other is the:placement of hydrophobic amino acid within the interior of the protein
Which of the following pairs of bonds within a peptide backbone show free rotation around both bonds?C(alpha)----C and N-----C(alpha)
In the alpha helix the hydrogen bonds:are roughly parallel to the x-axis of the helix
In an alpha helix, the R groups on the amino acids residues:are found on the outside of the helix spiral
Thr and/or Leu residues tend to disrupt an alpha helix when they occur next to each other in a protein because:steric hindrance occurs between the bulky Thr side chains
A D-amino acid would interrupt an alpha helix made of L-amino acids. Another naturally occurring hindrance to the formation of an alpha helix is the presence of:a Pro residue
The major reason that antiparallel beta-stranded protein structures are more stable than parallel beta-stranded structures is that the latter:have weaker hydrogen bonds laterally between adjacent strands
Amino acids residues commonly found in the middle of beta turn are:Pro and Gly
A sequence of amino acids in a certain protein is found to be -Ser-Gly-Pro-Gly-. The sequence is most probably part of a(n):beta sheet

Section 2

Question Answer
The three-dimensional conformation of a protein may be strongly influenced by amino acid residues that are very far apart in sequence. This relationship is in contrast to secondary structure, where the amino acid residues are:usually near the polypeptide chain's amino acid terminus or carbonyl terminus
Which of the following statements is false?Collagen is a protein in which the polypeptides are mainly in the alpha-helix conformation
Determining the precise spacing of atoms within a large protein is possible only through the use of:x-ray diffraction
Proteins often have regions that show specific, coherent patterns of folding or function. These regions are called:domains
Which of the following statements concerning protein domain is true?They may retain their correct shape even when separated from the rest of the protein
The structural classification of proteins (based on motifs) is based primarily on their:secondary structure content and arrangement
Proteins are classified within families or superfamilies based on similarities in:structure and/or function
Which of the following statement about oligomeric proteins is false?all subunits must be identical

Section 3

Question Answer
A repeating structural unit in a multimeric protein is known as a(n):protomer
An average protein will not be denatured by:iodoacetic acid
Which of the following is least likely to result in protein denaturation?changing the salt concentration
Experiments on denaturation and renaturation after the reduction and reoxidation of the -----S----S----- bonds in the enzyme ribonuclease (RNase) have shown that:the primary sequence of RNase is sufficient to determine its specific secondary and tertiary structure
Protein S will fold into its native conformation only when protein Q is also present in the solution. However, protein Q can fold into its native conformation without protein S. Protein Q, therefore, may function as a _____________ for protein S.molecular chaperone