Which of the following is true of transmembrane proteins?
a. The signal sequences are always cleaved off.
b. They are always inserted with the amino terminus on the lumenal side and the carboxyl terminus in the cytosol.
c. They cross the membrane only once.
d. They usually have one or more helices spanning the membrane bilayer.
Ans: d. They usually have one or more helices spanning the membrane bilayer.
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Biologically, which of the following is the least important characteristic of water?
A) Water molecules are polar. B) Water molecules have numerous hydrogen bonds. C) Water is a good solvent. D) Water typically contains isotopes of hydrogen. E) Water has a temperature-stabilizing capacity.
Energized myosin heads bind to actin only when ____ is present
a. myosin b. AMP c. calcium d. ATP e. sodium
Matter is composed of:
A. molecules B. atoms C. mass D. energy
Match the microscopy vocabulary word with it's definition.
Working distance A) Focus is maintained when the magnification is changed B) Ability to distinguish two objects as separate C) Area observed through the ocular lens D) Distance between the specimen and the objective lens