For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to
label nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling nitrogens would provide a stronger signal than labeling phosphate Why won't this work?A) There is no radioactive isotope of nitrogen.B) Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long.C) Avery, MacCloud and McCarty already did this.D) Although their are more nitrogens in a nucletotide, labeled phosphates actually have 16 extra neutrons; t Shift Ctrl herefore, they are more radioactive.E) Amino acids (and thus and proteins proteins
The correct option is <em>E. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.</em>
Explanation:
The element phosphate is actively present in the DNA but it is not present in the proteins.
Nitrogen is an active constituent of the DNA as well as the proteins. Hence, if nitrogen will be used for the Hershey and Chase experiment, then the results will that we will get will be wrong. We wouldn't be able to distinguish between the nitrogen atoms which came from the DNA and the nitrogen atoms which came from amino acid or proteins.
What drives the reabsorption to take place in the executory system is the presence of slow diffusion of some substances and active transport for others. Filtration removes the water form the blood and other substances get dissolved into blood.
