In a conjugated protein, a prosthetic group is:a) b) c) d) e) A fibrous region of a globular protein A nonidentical subunit of a protein with many identical subunits A part of the protein that is not composed of amino acids A subunit of an oligomeric protein Synomous with protomer

Consider an acetate buffer, initially at the same pH as its pKa(4.76). When NaOH is mixed with this buffer, the:a) pH remains constant b) pH rises more than if an equal amount of NaOH is added to an acetate buffer initially at pH 6.76 c) pH rises more than if an equal amount of NaOH is added to unbuffered water at pH 4.76 d) Ratio of acetic acid to sodium acetate in the buffer falls e)sodium acetate formed precipitates because it is less soluble than acetic acid

Water:a)b) c) d) e)

Is a good solvent for salts because of waters high dielectric constant Dissolves salts because the entropy of the water increases Forms extensive hydrogen bonds with the hydrocarbon portion of molecules Is held together largely by ionic interactions Forms entropically favorable cages around nonpolar molecules

Which statement concerning the peptide bond of proteins is correct?a) The carbonyl oxygen has a partial positive charge b) The hydrogen on the amide nitrogen has a partial positive charge c) The cis conformation is more stable than the trans configuration d) Hydrogen bonds between backbone carbonyl oxygens and amide hydrogens e) A high content of proline residues

The number of hydrogen bonds per amino acid:a)b)

c) d)

e)

Is greater in parallel b-sheets than anti-parallel bsheets Is greater in anti-parallel b-sheets than parallel bsheets Is the same in parallel and anti-parallel b-sheets Varies in parallel and anti-parallel b-sheets depending on the hydrophobicity of the side chains Hydrogen bonds are not a factor in parallel and anti-parallel b-sheets

The slope in the LineweaverBurk Plot is equal to:a) b) c) d) e) 1/Vmax Km -1/Km Km/Vmax Vmax/Km

Which of the following statements is true of the enzyme catalysts?a) To be effective, they must be present at the same concentration as their substrate b) They can increase the initial velocity of the reaction and lower the Ea for the conversion of substrate to product c) They can increase the equilibrium constant for a given reaction by a 1000-fold or more d) Their catalytic activity is independent of pH e) They are generally equally active on D and L isomers of a given substrate

At pH 7.0 converting a proline to hydroxyproline will have what effect on the overall charge of the protein containing it?a) b) c) d)e)

It will become more negative It will become more positive It will stay the same There is not enough information to answer the questionThe answer depends on salt concentration

For the study of a protein in detail, an effort is usually made to first:

a) Conjugate the protein to a known molecule b) Determine its aa composition c) Determine its aa sequence d) Determine its molecular weight e) Purify protein

A protein is in its native conformation when:a) it is thermodynamically least stable b) It has the highest free Gibbs free energy c) It is in any of its functional, folded states d) It is unfolded

Which one of the following statements concerning the peptide shown below is correct? Gly-Cys-Glu-Ser-Asp-Arg-Cys a) The peptide contains glutamine. b) The peptide contains a side chain with a secondary amino group. c) The peptide contain a majority of amino acids with side chains that would be positively changed at ph 7. d) The peptide is able to form an internal disulfide bond.

A peptide bond: a) Has a partial double-bond character b) Is ionized at physiological pH c) Is cleaved by agents that denature proteins, such as organic solvents and high concentration of urea d) Is stable to heating in strong acids e) Occurs most commonly in the cis configuration

Which one of the following statements in correct? a) The alpha-helix can be composed of more than one polypeptide chain b) Beta-sheets exist only in antiparallel form c) Beta-bends often phone proline d) Domincas are a type of secondary structure e) The alpha-helix is stabilized primiarly by ionic interactions between the side chains of amino acids

Which one of the following statements about proteins structure is correct? a) Proteins consisting of one polypeptide can have quarternary structure b) The formation of disulfide bond in a protein require that the 2 participating cysteine residues be adjacent to each other in the primary sequence of the protein c) The stability of quarternary structure in proteins is mainly a result of covalent bonds among the subunits d) The denaturation of proteins always lead to irreversible loss of secondary and tertiary structure e) the information required for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain

An 80-year-old man presented with impairment of higher intellectual funcation and alteraions in mood and behavior. His family reported progressive disorientation and memory loss over the last six months. There is no family history of dementia. The patient was tentatively diagnosed with Alzheimer disease. Which one of the following best describes the disease? a) It is associated with beta-amyloid - an abnormal protein with an altered amino acide sequence b) It results from accumulation of denatured proteins that have random conformations c) It is associated with the accumulation of amyloid precursor protein d) It is associated with the deposition of neurotoxic amyloid peptide aggregates e) It is an environmently produced disease not influenced by the genetic of the individual

Which one of the following statements concerning the hemoglobins is correct? a) Fetal blood has a higher affinity for oxygen than does adult blood because Hb F has a decreased affinity for 2,3BPG b) Purified Hb F (stripped of 2,3-BPG) has a higher affinity for oxygen than does purified Hb A c) The chain

1-c 2-d 3 - e? 4 - b? 5 - b? 6-e 7-b 8-c 9-e 10 -

11 - d 12 - c 13 - e 14 - d