Legible Name _______________________________________________________________________
BIO354: Cell Biology Laboratory
Laboratory Quiz 04
01. Your standard curve for protein was able to be used to calculate mass of protein in the
"unknown" sample tube, because _____.
A. spectrophotometry corrects for any discrepancies of concentration
B. all tubes contained the same volume of solution
C. most proteins have the same mass as bovine serum albumin
D. amino acids do not react with buffer
02. As part of the last assignment, you were asked to use the results of a hypothetical experiment to
calculate _____.
A. a molar extinction coefficient for hemoglobin
B. the wavelength of optimum absorbance for BSA
C. absorbance of plasma albumin
D. concentration of serum creatinine
03. If a standard curve for Substance A, fitted to a plot of absorbance versus g, is described by the
line y=2.0x, and an appropriately prepared cuvette yields a spectrophotometric absorbance of 1.0,
what is the expected mass of Substance A in the cuvette?
04. When constructing a standard curve for BSA, the absorbance values for some of the most highly
concentrated standard solutions might have to be discarded, because _____.
A. they deviate from linearity
B. the spectrophotometer has a maximum level of absorbance it is able to measure
C. at high concentrations, BSA molecules react with each other, forming opaque products
D. at high concentrations, BSA neutralizes the pH of the buffer
05. Another name for -galactosidase is _____.
A. alcohol dehydrogenase
B. galactase
C. maltase
D. lactase
06. Lactose is _____.
A. a monosaccharide
B. a disaccharide
C. a monopeptide
D. a dipeptide
07. Any particle that can bind to a binding site on a protein is called _____.
A. a pleated sheet
B. an  helix
C. a ligand
D. an enzyme
Never assume completeness without checking the reverse.
08. A typical plot of an enzyme's initial velocity versus substrate concentration features a horizontal
asymptote (i.e., a plateau). This is a graphical representation of _____.
A. dynamic equilibrium
B. static equilibrium
C. catalytic reversibility
D. thermal sensitivity
E. substrate saturation
09. ONPG will serve as the _____ in today's experiment.
A. enzyme
B. catalyst
C. substrate
D. activator
E. buffer
10. Today, you will assess enzyme activity by directly measuring the_____.
A. spectrophotometric absorbance of product molecules
B. spectrophotometric absorbance of substrate molecules
C. spectrophotometric absorbance of enzyme molecules
D. mass of product molecules
E. mass of substrate molecules
F. mass of enzyme molecules