Question

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 20.5% thymine and sample B contains 31.5% thymine. Assume the organisms contain normal double-stranded DNA and predict the composition of the other bases. percent adenine in sample A: %A percent guanine in sample A: %G percent cytosine in sample A: %C about us career privacy policy terms of use help contact us 7:24 PM B 0 3/18/2020 е .

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Answer 1

The question provides measured percentages of thymine in two samples isolated from the Deepwater Horizon leak. In DNA, thymine and adenine exist in pair. So, percentage of adenine in any DNA sample will be equal to percentage of thymine in that sample.

In order to individual predict percentages of guanine and cytosine, we will first calculate percentage of total guanine and cytosine in a DNA sample. This requires subtraction of total percentage of adenine and thymine in sample from 100. Then, we will calculate individual percentages of guanine and cytosine by halving percentage of total guanine and cytosine because guanine and cytosine form pair in DNA. Please have a look at calculations given below.

Sample A

Measured percentage of thymine in sample A = 20.5%

Predicted percentage of adenine in sample A = 20.5%

In order to predict percentages of guanine and cytosine in sample A, we will first calculate sum of measured percentage of thymine and predicted percentage of adenine in sample A.

Sum of measured percentage of thymine and predicted percentage of adenine in Sample A = 20.5% + 20.5%

Sum of measured percentage of thymine and predicted percentage of adenine in Sample A = 41 %

We will substract sum of measured percentage of thymine and predicted percentage of adenine in Sample A from 100. This will give us percentage of total guanine and cytosine in a sample A.

Percentage of total guanine and cytosine in sample A = 100- sum of measured percentage of thymine and predicted percentage of adenine in Sample A

Percentage of total guanine and cytosine in sample A = 100- 41 %

Percentage of total guanine and cytosine in sample A = 59%

We will calculate individual percentages of guanine and cytosine by halving percentage of total guanine and cytosine in sample A.

Percentageof totalguanineandcytosinein sample Predictedpercentageof guaninein sample.A =

Predictedpercentageof guanineinsample A =

%

Predictedpercentageof guaninein sample A =

Predicted percentage of guanine in sample A = 29.5%

Predicted percentage of cytosine in sample A = 29.5%

Sample B

Measured percentage of thymine in sample B = 31.5%

Predicted percentage of adenine in sample B = 31.5%

Sum of measured percentage of thymine and predicted percentage of adenine in Sample B = 31.5% + 31.5%

Sum of measured percentage of thymine and predicted percentage of adenine in Sample B =  63%

Percentage of total guanine and cytosine in sample B = 100- sum of measured percentage of thymine and predicted percentage of adenine in Sample B

Percentage of total guanine and cytosine in sample B = 100- 63 %

Percentage of total guanine and cytosine in sample B = 37%

=Percentageof totalguanincandcytosiner sample Predictedpercentageof quaninein sample

%

Predictedpercentageof guaninein sampleB = 18.5

Predicted percentage of guanine in sample B = 18.5%

Predicted percentage of cytosine in sample B = 18.5%

Temperature required for denaturation of any DNA sample depends on the presence of guanine and cytosine in that DNA sample. DNA sample with higher percentage of guanine and cytosine requires higher temperature to denature because guanine and cytosine pair in DNA consists of triple hydrogen bonds. But, adenine and thymine pair consists of double hydrogen bonds. Percentage of total guanine and cytosine in sample A is 59%. This is higher than percentage of total guanine and cytosine in sample B (37%). So, sample A will have higher temeperature to denature.