What are the similarities and differences of intermolecular interactions that stabilize secondary versus tertiary structure? Think about types of interactions, side-chain versus backbone interactions, and proximity of the residues involved.

Peptide bonds cannot rotate. This is because: a) the amino acid side chains are too bulky to allow this. B) Internal hydrogen bonding hinders rotation.   C) interaction with water molecules hinders rotation  D) the peptide bond has considerable double bond character Polypeptide chains prefer the trans conformation. This is because: a) This distances hydrophilic groups from hydrophobic groups b) this minimizes crowding of side chains   c) This brings hydrophilic groups in contact with water molecules   d)  This allows proteins to fold more easily Ramachandran plots indicate that protein conformation is largely a function of: a) hydrophobicity b)  number of amino acids   c) torsion angles    d)  arrangement of prosthetic groups

Which of the following statements are False? (i)     Parallel b-sheets characteristically distribute hydrophobic side chains on both sides of the sheet, and antiparallel B-sheets are usually arranged with all their hydrophobic residues on one side of the sheet. (ii)   Planarity of the peptide bond means that no rotation occurs about the N-Ca bond while rotation is allowed about the C(O)-N and Ca-C(O) bonds. (iii) Silk fibers consist of fibroin proteins consisting of alternating A and G or S residues. (iv) If an aspartic acid residue were present in the interior of a globular protein, it would most likely be deprotonated and thus negatively charged.

Match the following terms to the correct definition: disulfıde bonds V [ Choose ] molecular force between non-polar molecules resulting from temporary dipoles covalent bonds between two cysteines salt-bridges intermolecular interactions that occur between the R groups of positively and negatively charged residues bonds between R-groups, carbonyls and amides that are not used in forming the secondary structure van-der Waals forces [ Choose ] internal hydrogen bonds [ Choose ]

The bottom peptide segment is found in the secondary structure composed of anti-parallel - sheets. From the C-terminus of the peptide below, the sequence immediately after alternation contains the following amino acid residues (from N → C) A-F-R-M-Y-A. a) which side do you expect to face the solvent? Briefly explain your reasons NH, но Nterminus

Select the properties that apply to the secondary structure alpha helices (select all that apply). U 0 can be Antiparallel can be Parallel are typically right handed are typically left handed obeys n+4 rule are formed by the pattern of hydrogen bonding the backbone makes with itself are formed by the pattern of covalent bonds the backbone makes with itself are formed by the pattern of electrostatic attractions the backbone makes with itself

Which of the following statement about proteins is correct a. alpha helix and Beta pleated sheets are considered quaternary structures b. a single polypeptide only has primary sytructure, secondary, tertiary, and quaternary structures require more than one polypeptide c. there are 30 essential amino acids that are the monomer building blocks of proteins d. polypeptides have a distinct polarity (directionality) with one end refered to as the free amino end, and the other called the free carboxyl end