In a famous experiment, matthew meselson and franklin stahl grew e. coli cells in a medium containing only the "heavy" isotope of nitrogen, n15n15 . these cells were then transferred to a medium with the "light" isotope of nitrogen, n14n14 . the results of the experiment supported the hypothesis of semiconservative replication, which was proposed by watson and crick. heavy dna ( n15n15 dna), hybrid dna, and light dna ( n14n14 dna) can be separated by centrifugation. if cells containing n15n15 dna are transferred to a medium with only n14n14 nh4clnh4cl as a nitrogen source, what percent of daughter molecules are composed of hybrid dna after 44 generations?

The endoplasmic reticulum (er) is an organelle in some cells. in these cells, it is continuous with the nuclear membrane and forms a large part of the cell\'s total membrane. sort the phrases below as describing rough er, smooth er, both, or neither. note: if you answer any part of this question incorrectly, a single red x will appear indicating that one or more of the phrases are sorted incorrectly.1) found in prokaryites and uekaryotys2) involved in protein synthesis3) involve in lipid synthesis4) contains molecular chaperones in lumen5) bound with ribosomes6) involved in toxin or drug metabolism7) large systemot internnected tubules,vesicles, and sacs8) "packages" enzymes in vesicles for secretion.

Name the part of the the brain labeled "e".

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point