Part 1 of 3 Suppose you provide radioactive dGTP to bacteria for 2 generations.
ID: 217433 • Letter: P
Question
Part 1 of 3
Suppose you provide radioactive dGTP to bacteria for 2 generations. You then isolate the DNA from the bacteria. Assume you put the radioactivity in the right part of the dGTP so that radioactivity is incorporated into the newly made DNA.
After the 2 generations what fraction of the double stranded molecules should contain radioactivity?
sugar
phosphate closest to the sugar
phosphate farthest from the sugar.
any of the phosphates
the base G (guanine).
the sugar attached to the G base.
0
1/10
1/8
1/4
1/3
1/2
3/8
2/3
3/4
7/8
1/1 (all)
some other fraction.
Part 3 of 3.
Suppose you provide radioactive dGTP to bacteria for 2 generations. You then isolate the DNA from the bacteria. Assume you put the radioactivity in the right part of the dGTP so that radioactivity is incorporated into the newly made DNA.
Suppose you isolate the ds DNA as in part 1 of the question and then you hydrolyze the DNA into monophosphates, you then separate the 4 monophosphates to see which are radioactive.
Hydrolysis (breakdown) of DNA chains can give 3' or 5' monophosphates, depending on how the phosphodiester bond is broken. 3' monophosphates have the P attached to the 3' position of the sugar' 5' monophosphates have the P at the 5' end of the sugar.)
When you break down the DNA to get 3' monophosphates, the radioactivity is found in all 4 different monophosphates-dGMP, dCMP, dAMP, and TMP (dTMP is redundant). When you break down the DNA to get 5' monophosphates, all the radioactivity is in dGMP.
Given these results where was the radioactivity in the dGTP you started with?
The radioactivity was probably in the ________
0
1/10
1/8
1/4
1/3
1/2
3/8
2/3
3/4
7/8
1/1 (all)
some other fraction.
Part 2 of 3.
Suppose you provide radioactive dGTP to bacteria for 2 generations. You then isolate the DNA from the bacteria. Assume you put the radioactivity in the right part of the dGTP so that radioactivity is incorporated into the newly made DNA.
Now suppose you denature the ds DNA and measure the radioactivity in single strands. After 2 generations the fraction of single strands containing radioactivity should be ____.
0
1/10
1/8
1/4
1/3
1/2
3/8
2/3
3/4
7/8
1/1 (all)
some other fraction.
sugar
phosphate closest to the sugar
phosphate farthest from the sugar.
any of the phosphates
the base G (guanine).
the sugar attached to the G base.
Explanation / Answer
radioactivity in the right place means either you have to incorporate either radiolabeled phosphate group which is near to the sugar (alpha PO4 group) or radiolabeled nitrogen which is present in the nitrogenous base.
and as we know the replication is semiconservative so in the first generation from 1 cell 2 cell will form and from 2 cell 4 cell will form (2nd generation). and After the 2 generations fraction of the double-stranded molecules that contain radioactivity is 1/2 (bcoz out of 4 cells 2 cells contain full radioactive ds DNA and two cell contain one strand radioactive).