Mammalian cells were grown in a cell culture medium that contains large amounts of uracil labeled with radioactivity on the two nitrogens in the uracil ring.  Assume that this radioactivity nitrogen remains in uracil and cannot be transferred to any other molecule.  Which of the following molecules would probably contain […]

With much of the focus of atmospheric pollution on climate-changing gases such as carbon dioxide (CO2), there can be a tendency to downplay the risk posed by other pollutants. One such pollutant is sulfur dioxide, the chemical involved in acid rain, which is discussed in your chapter readings, and can […]

As multicellular organisms decelop from embryo to adults, gap junctions are made and broken in specific patterns, involving specific tissues. This suggests that these junctions play an important role in signalling between cells during embryonic development. A) With the understanding of Gap junctions, speculate on what sorts of signalling molecules […]

Although standard redox potentials of NAD+ and NADP+ are essentially the same, and both are capable of carrying high-energy electrons, they are used in very distinct reactions in cells. Explain why NAD+/NADH+H+ is preferentially used for catabolic reaction (e.g. cellular respiration and glucose breakdown) and NADP+/NADPH+H+ is predominantly used for […]