The attraction between Na+ cations and Cl- anions form ____ that hold the ions together in the compound NaCl
a. polar covalent bonds
b. van der Waals forces
c. ionic bonds
d. hydrogen bonds
e. nonpolar covalent bonds
ANSWER: c
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Which of the following represents a blind study?
A. The test group does not know whether they are receiving a placebo or the actual treatment, but the researchers do. B. Neither the test group nor the researchers know whether the test group is receiving a placebo or the actual treatment until all the data are collected. C. The test group knows whether they are receiving a placebo or the actual treatment, but the researchers do not know until all the data are collected. D. The test group knows whether they are receiving a placebo or the actual treatment, and so do the researchers.
Most members of this lineage of Cnidarians have both polyp and medusa stages in their life cycles,
with the polyp stage typically forming a colony. Species of Obelia are members of this lineage.
a. Hydrozoa b. Scyphozoa c. Trematoda d. Cubozoa e. Anthozoa
Hydropathy analysis of a membrane protein's amino acid sequence predicts the protein's transmembrane segments and orientation in the membrane
It is necessary to confirm those predictions with experimental analysis. One experimental approach for plasma membrane proteins is to use the protease trypsin to digest extracellular domains of these proteins. (Trypsin is hydrophilic and cannot cross the plasma membrane to enter the cell.) When added to cells, trypsin digests the hydrophilic portions of plasma membrane proteins exposed outside the cell into small fragments but will not have access to transmembrane or cytosolic regions of proteins. Design a general experiment using trypsin and SDS-PAGE to address membrane protein association and orientation, and describe specific expected results that would be consistent with the following predicted membrane protein associations and orientations: a. a singlepass integral membrane protein with only its N-terminus exposed on the extracellular surface b. a singlepass integral membrane protein with only its C-terminus exposed on the extracellular surface c. a multipass integral membrane protein with only three hydrophilic loops exposed on the extracellular surface d. a fatty acylated protein e. a GPI-anchored protein What will be an ideal response?
Which of the following antifungals works by binding to ergosterol in membranes?
A) fluconazole B) turbinafine C) amphotericin B D) nystatin E) both amphotericin B and nystatin