Nucleic Acid Mastering Help 1. 2. 3. I thought my answer was right but it says i
ID: 304588 • Letter: N
Question
Nucleic Acid Mastering Help
1.
2.
3. I thought my answer was right but it says it is wrong
5-Bromouracil, a highly mutagenic compound (that is, a compound that causes changes in DNA), is used in cancer chemotherapy. When administered to a patient, it is converted to the triphosphate and incorporated into DNA in place of thymine, which it resembles sterically. Why does it cause mutations? (Hint: The bromo substituent increases the stability of the enol tautomer.) Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer. Note: not all words will be used. Reset Help guanine cytosine adenine uracil 1. 5-Bromouracil is incorporated into DNA in place of thymine because of their similar size. Thymine pairs with adenine via two hydrogen bonds. 5-Bromouracil exists primarily in the enol form. The enol cannot form any hydrogen bonds with adenine, but it can form three hydrogen bonds with guanine. Therefore, 5-bromouracil pairs with guanine. Because 5-bromouracil causes guanine to be incorporated instead of adenine into newly synthesized DNA strands, it causes mutations. one two three Submit Previous Answers Request Answer X Incorrect, Try Again; 3 attempts remaining; no points deducted You filled in 1 of 8 blanks incorrectly.Explanation / Answer
1. Here is the mistake, 5-bromouracil can form two hydrogen bonds with guanine, one with carbonyl group and the other one with amino group. So, the correction will be
but it can form two hydrogen bonds with guanine.
2. According to Chargaff's rule the ratio of pyridimine base to purine base should be 1:1
so the pairs will be GA and TC, CC and AA , CC and GG .
The first, second and third options are correct.
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