Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

[Q]: Context: Previous X-ray crystal structures have shown that linkers of five amino acid residues connecting pairs of chicken brain alpha-spectrin and human erythroid beta-spectrin repeats can undergo bending without losing their alpha-helical structure. To test whether bending at one linker can influence bending at an adjacent linker, the structures of two and three repeat fragments of chicken brain alpha-spectrin have been determined by X-ray crystallography. The structure of the three-repeat fragment clearly shows that bending at one linker can occur independently of bending at an adjacent linker. This observation increases the possible trajectories of modeled chains of spectrin repeats. Furthermore, the three-repeat molecule crystallized as an antiparallel dimer with a significantly smaller buried interfacial area than that of alpha-actinin, a spectrin-related molecule, but large enough and of a type indicating biological specificity. Comparison of the structures of the spectrin and alpha-actinin dimers supports weak association of the former, which could not be detected by analytical ultracentrifugation, versus strong association of the latter, which has been observed by others. To correlate features of the structure with solution properties and to test a previous model of stable spectrin and dystrophin repeats, the number of inter-helical interactions in each repeat of several spectrin structures were counted and compared to their thermal stabilities. Inter-helical interactions, but not all interactions, increased in parallel with measured thermal stabilities of each repeat and in agreement with the thermal stabilities of two and three repeats and also partial repeats of spectrin. 
 Question: Alpha-spectrin and beta-spectrin subunits form parallel or antiparallel heterodimers?
[A]: antiparallel


[Q]: Context: Even while in a deep sleep, people can still learn brand new information. Sleepers soak in new associations between smells and sounds, knowledge that lingers into the next waking day, researchers report online August 26 in Nature Neuroscience. The new study is the first to show that entirely new information can get into the sleeping mind, says Anat Arzi of the Weizmann Institute of Science in Israel. "The brain is not passive while you sleep. It's quite active. You can do quite a lot of things while you are asleep." But the results don't mean that Spanish vocabulary tapes now have a place on the nightstand. L, Researchers have tried but largely failed to find evidence that complicated information, such as new pairs of words, can make its way into the brain during sleep. Instead of trying to teach people something complicated like a new language, Arzi and her colleagues relied on the sense of smell and hearing. As anyone who has walked by a dumpster in July knows, smells can cause a nose-jerk reaction. Catching a bad smell automatically makes people inhale less, reducing the size of the inhale. But scent of fresh bread causes a long, deep inhale., rzi and her team took advantage of this reaction for their experiment. As people slept in the laboratory, the researchers delivered pleasant scent, such as shampoo. As this nice smell got into the sleepers' noses, the researchers played a particular music. Later, a disgusting smell, such as rotten fish or meat, was paired with a different music. Neither the smell nor the sound woke people up. After just four exposures to the smell-music pair during a single night, the sleepers started to automatically respond to the tones without the accompanying smells, taking in bigger breaths when the shampoo-associated tone played and smaller breaths when played the sound linked to the rotten fish smell. This new learned association lingered into the next waking day, too. Even though the sleepers had no idea they had been exposed to smells or sounds, their behavior proved that their brain had actually learned something during sleep. As before, the shampoo sound stimulated a long, deep inhale, while the rotten fish tone caused more shallow breaths. 
 Question: In which part of a website may this passage most likely appear?
[A]: science.


[Q]: Context: Watanabe et al (Reports, 12 April 2013, p. 195) study the yeast SWR1/SWR-C complex responsible for depositing the histone variant H2A.Z by replacing nucleosomal H2A with H2A.Z. They report that reversal of H2A.Z replacement is mediated by SWR1 and related INO80 on an H2A.Z nucleosome carrying H3K56Q. Using multiple assays and reaction conditions, we find no evidence of such reversal of H2A.Z exchange. 
 Question: Which protein mediates the replacement of H2A by H2A.Z in the yeast Saccharomyces cerevisiae?
[A]:
swr1


