Tutor profile: Jason B.
Catalytic domains on Map kinases must be phosphorylated on amino acid 141 to be chemically active. In order to produce a kinase dead mutant, a catalytically-inactive enzyme, which would be a likely mutation on its active site? a) S141Y b) Y141T c) T141Y d) Y141W
D is the correct answer. In order for the Map kinase to be inactive, it cannot have a phosphorylated active site. During phosphorylation, a phosphate group attaches to a hydroxyl (OH) group of either Tyrosine (Y), Threonine (T), or Serine (S). These are the only three amino acids with a hydroxyl side chain. Only choice D shows a mutation from a hydroxyl-containing amino acid into a non-hydroxyl-containing amino acid: tyrosine (Y) to tryptophan (W).
What would be a reason to include both ERP and fMRI image testing in a cognitive psychology experiment? a) ERP testing provides better temporal resolution while an fMRI offers more exact location information. b) ERP testing provides better spatial resolution while an fMRI has a faster sample collection time. c) fMRI testing provides increased temporal resolution while ERPs offer better data on localization. d) fMRI testing provides increased spatial resolution while ERPs collect less samples per second.
The correct answer is A. ERPs have better temporal resolution, so they can collect more samples per second. fMRIs have better spatial resolution, so they are better at precise localization. Although choice D correctly states that fMRIs have better spatial resolutions, it incorrectly states ERPs have slower sampling rates.
Which of the following statements is NOT true regarding muscle contractions? a) Action potentials travel through the T-tubules to trigger Ca2+ release in the sarcoplasmic reticulum. b) Ca2+ ions bind to tropomyosin, moving troponin out of the way to expose the actin active sites. c) Myosin detaches from actin as ATP is hydrolyzed after a power stroke. d) Ca2+ ions are moved back into the sarcoplasmic reticulum through active transport.
B is the correct answer. Ca2+ ions bind to troponin, which moves tropomyosin out of the way in order to expose the actin active sites for myosin attachment. (Binding occurs on troponin, not tropomyosin) All other answer choices are true statements.
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