The half-life of the C14 isotope is 5730 years. How many years after an animal dies will it take for the concentration of C14 to decrease to 12.5 percent (1/8th) of its original level?

Using the pka data for lysine, draw the molecular species present at each of the following pH values and determine the overall charge on the population of molecules. For the amino acid lysine use the pKas of 2.2, 9.0, and 10.0 for the ionizable groups. Please show work by showing the charge of each group, thank you. a) pH 2.2 1 b) pH 9.5

(I) Why the physicochemical changes in liquid water caused by radiation is the key to understanding the biological effects of radiation? Please give a short, one-sentence explanation. (II) Name the three key stages of the physicochemical changes produced in liquid water due to radiation. (III) Briefly describe the three key stages. A one- or two-sentence explanation for each of the three key stages would be sufficient.

(6) With regard to the nitrogen cycle, even though nitrogen makes up approximately 78% of our atmosphere, it is relatively scarce in the lithosphere, hydrosphere, and in organisms. It is however an essential ingredient in the proteins DNA and RNA vital for the organisms on Earth. According to our textbook, nitrogen gas (N2) is chemically inert and cannot cycle out of the atmosphere and into living organisms without all of the following EXCEPT: (a) Nuclear isotope decay is taking place in close proximity to the cycling (b) There is nitrogen fixing bacteria present (c) Lightning occurs (d) Human intervention

Write the missing element in the following nuclear reactions. Include mass and atomic number. Type answer following this example: 237 U-237 Np + a. 73 Ga-73 Ge+ b. 192 Pt 188 Os+ C. 205 Bi-205 Pb+ (answer would be 92, 93, -Beta) d. 241Cm + 241 Am type your answer... type your answer... type your answer... type your answer....

A starved subject is fed with radio labeled protein (with NT5 and C14). Breath, blood, urine and liver samples are analyzed for chemical composition. List the names of the different compounds that will be labeled with radioactive carbon or nitrogen in the four different samples (state which compounds will be labeled with N15 and which will be labeled with C'14). Sample 1: Liver Sample 2: Breath Sample 3: Blood Sample 4: Urine

A purified protein fraction has a total sample volume of 360 µL.  The sample has a corrected A280 of 0.484, and the blank corrected A280 was 0.052.  (Both values were measured with a path length of 1.00 cm.)  If 5.00 µL of the sample was used in a reaction, calculate the mass of protein in the reaction (in µg).

If a DNA molecule is found to be 16% Guanine, how much Thymine is in the molecule?