#Question id: 1647
#Unit 4. Cell Communication and Cell Signaling
A fragment antigen binding (Fab) fragment:
#Question id: 2585
#Unit 2. Cellular Organization
Which of the following is the correct sequence that describes the excitation and contraction of a skeletal muscle fiber?
A. Tropomyosin shifts and unblocks the cross-bridge binding sites.
B. Calcium is released and binds to the troponin complex.
C. Transverse tubules depolarize the sarcoplasmic reticulum.
D. The thin filaments are ratcheted across the thick filaments by the heads of the myosin molecules using energy from ATP.
E. An action potential in a motor neuron causes the axon to release acetylcholine, which depolarizes the muscle cell membrane.
#Question id: 12913
#Unit 13. Methods in Biology
#Question id: 3720
#Unit 3. Fundamental Processes
The 3ʹ → 5ʹ exonuclease activity of E. coli DNA polymerase III accounts for the ________ of polymerization.
#Question id: 641
#Unit 1. Molecules and their Interaction Relevant to Biology
Which of the following does NOT describe a mechanism that cells use to regulate enzyme activities?
A. Cells control enzyme activity by phosphorylation and dephosphorylation.
B. Cells control enzyme activity by the binding of small molecules.
C. Cells control the rates of diffusion of substrates to enzymes.
D. Cells control the rates of enzyme degradation.
E. Cells control the rates of enzyme synthesis.
F. Cells control the targeting of enzymes to specific organelles.