Question

Attempt 4 - Bacteria and other microbes can be used to clean up an oil spill by breaking down oil into carbon dioxide and water. Two samples isolated from the Deepwater Horizon leak in the Gulf of Mexico were labeled A and B. The DNA of each was isolated and the percent thymine measured in each sample Sample A contains 19.5% thymine and sample B contains 27.5% thymine. Assume the organisms contain normal double-stranded DNA and predict the composition of the other bases. percent adenine in sample A: percent guanine in sample A: percent cytosine in sample A: percent adenine in sample B: percent guanine in sample B: percent cytosine in sample B:

Answer 1

Adenine forms complementary base pairing with Trimine, so adinine will be of same & percentage as that of Thymine In sample a thymine is 19.5% percent adenine in sumple A is 19.5% Fireent of Granine lytosine) in sample A 2(100 - 2x1915) - 617. the amount of Guanine and cytosine is same for a particular DNA as they form complementary base pairing percent of Guanine in sample A = 612 30.5% krunt of Cytosine is sample B = 30.5% The sample B contains 27.5%. thymine percent of Adenine in sample B = 27.59. Percent of (Guanine lytsine) = 45% Amount of Guanine in sample B = 4 5 = 22.59. Amount of cytosine in sample B= 22.5%. 2x2

Answer 2

In any DNA sample

Amount of thymine =amount of adenine

Amount of cytosine=amount of guanine

Sample A

℅ of thymine=19.5

℅of adenine=19.5

Let ℅of guanine=℅of cytosine=X

So

℅ of (Adenine+thymine+guanine+ cytosine)=100

X+X+19.5+19.5=100

2x+39=100

100-39=61=2x

X=61/2=30.5

So ℅ of guanine=℅of cytosine=30.5℅

In sample B

℅ of thymine=27.5

℅of adenine=27.5

Let ℅of guanine=℅of cytosine=X

So

X+X+27.5+27.5=100

2x+55=100

100-55=45=2x

X=45/2=22.5

So ℅ of guanine=℅of cytosine=22.5