A gene can be defined as:
a specific segment of nucleotide bases in DNA that encode for the synthesis of a particular protein.
Where C? is the ?-carbon, N represents the amide nitrogen and Co is the carbonyl carbon of amino acids in a peptide, the peptide backbone of a protein consists of the repeated sequence:
-N-C?-Co-
The peptide bond has partial _______________ character.
double bond
Resonance in peptide bonds results in all EXCEPT:
a. approximately 40% double bond (coplanar) character.
b. restricted rotation in the peptide backbone at the N-C? bond and C?-Co bond.
c. the coplanar six atoms of the peptide bond group of atoms.
d. a C?-
D
The amide plane of the peptide backbone includes all the atoms EXCEPT:
a. C?-carbon.
b. amide nitrogen.
c. side chain carbons.
d. carbonyl carbon.
e. none, all are included.
side chain carbons
Proteins with two different polypeptide chains are
heterodimeric proteins
Hemoglobin is an ?2, ?2 _______ whereas, glutamine synthatase from E. coli is an ?12 _______________.
-heteromultimer, -homomultimer
Fibrous proteins, such as collagen, have which one of the following properties?
Serve structural roles in the cell
Globular proteins are usually all EXCEPT:
a. Insoluble in water.
b. Roughly spherical.
c. Folded so that the hydrophobic amino acids are in the interior of the molecule.
d. Hydrophobic side chains are exposed to the water.
e. None, all are true.
A
10. Molecules of a given protein have all EXCEPT:
a. a fixed amino acid composition.
b. a defined amino acid sequence.
c. a sequence read from C-terminal end to N-terminal end.
d. an invariant molecular weight.
e. a nucleotide sequence from which they are
C
Membrane proteins differ from globular proteins in that
membrane proteins are much more soluble in detergents than water.
A common reaction of two cysteine residues in proteins results in the formation of _______.
disulfide bonds
The amino acid sequence is defined as __________ structure.
primary
?-Helix and ?-strand are components of __________ structure
secondary
All of the information necessary for a protein to achieve its intricate architecture is contained within its __________ structure.
primary
The formation of a disulfide bond would be an example of what level of protein structure?
tertiary, quaternary
17. A protein's particular conformations are all EXCEPT:
a. The overall three-dimentional architecture of the protein.
b. Achieved by breaking and reforming covalent bonds.
c. Achieved by rotations about each single bond along the peptide backbone.
d. The
B
Which of the following levels of protein structure is correctly defined?
a. primary: interaction between subunits of a protein
b. secondary: hydrogen bond arrangement of polar R-groups
c. tertiary: three dimensional arrangement of all atoms in a single pe
C
Protein isolation and purification include all of the techniques EXCEPT:
a. gas-liquid chromatography.
b. ion exchange chromatography.
c. electrophoresis.
d. solubility ("salting in" and "salting out").
e. affinity chromatography.
A
Even though acid hydrolysis of proteins is favored over basic hydrolysis, with acid hydrolysis ___________ is destroyed and must be estimated by other means.
Trp
Amino acid analysis of a protein gives:
the percentage or ratio of the various amino acids in the protein.
22. The amino acid sequence is NOT:
a. a distinctive characteristic of a polypeptide.
b. encoded by the nucleotide sequence of DNA.
c. a form of genetic information.
d. read from N-terminal end to C-terminal end.
e. constant for proteins with the same fun
E
Edman degradation will:
determine the N-terminal amino acid.
After treating a protein with trypsin, which of the following techniques could be used to determine its identity by peptide mass fingerprinting?
MALDI-TOF mass spectrometer
Reaction of the peptide, ala-met-lys-ser, with phenylisothiocyanate (PITC) at pH 8.0 followed by mild acidification (first cycle of Edman method) would release:
PTH-ala and the peptide met-lys-ser.
What is the product formed from the acid hydrolysis of a simple amide?
acid & amine
When sequencing a heteromultimer, all are useful methods of dissociating the multimeric protein EXCEPT:
a. Exposure to pH extremes.
b. High salt concentrations.
c. 6 N HCl at 110oC for 24 hours.
d. 8 M urea.
e. 6 M guanidinium chloride.
C
Insulin is a polypeptide hormone that contains two short polypeptide chains linked by two interstrand disulfide bonds. The most logical order of events to perform in order to sequence this protein would be:
A: The peptides are reduced with mercaptoethanol
A, D, C, B
The C-terminal residue of a polypeptide can be determined by first cleaving the polypeptide with:
carboxypeptidase
___________ is specific in hydrolyzing only peptide bonds in which the carboxyl function is contributed by an arginine or a lysine residue.
Trypsin
The advantage of treating separate samples of a protein with two or more enzymes when sequencing a protein is that the products are:
fragments with sequence overlaps.
What is the overall net charge on the peptide lys-lys-ser-glu at pH 7.0?
1
All of the statements about the peptide val-asp-trp-asn-ser are correct EXCEPT:
a. This peptide would show a strong absorption band at 280 nm.
b. Reaction with chymotrypsin would yield two peptides.
c. To synthesize this peptide using the solid phase meth
E
Determine the amino acid sequence of the following oligopeptide from the experimental data below.
1. The amino acid composition is found to be [ala, lys, phe, met, cys, plus some decomposition products].
2. The peptide has a molecular weight around 700 Da
lys-met-cys-phe-ala-trp
The preponderance of protein sequence information is now derived from:
translating the nucleotide sequence of genes into codons, and thus amino acid sequence.
Homologous proteins such as hemoglobin from different organisms do NOT:
a. have nearly identical lengths.
b. share little sequence homology with other proteins with similar function (e.g., myoglobin).
c. share a significant degree of sequence similarity.
B
Although they have very different functions, hen egg white lysozyme and __________ share similar sequence homology and similar tertiary structure.
?-lactalbumin
The diversity in hemoglobin mutants indicates that:
specific amino acid changes drastically alter one or more functions of a protein.
Proteins destined for an extracellular location are characteristically:
glycoproteins.
Proteins that do NOT perform any obvious chemical transformation, but control the ability of other proteins to carry out their physiological functions are:
regulatory proteins.
Hemoglobin is an example of a(n):
transport protein.
Collagen is an example of a(n):
structural protein.
The lac repressor is an example of a(n):
regulatory protein.