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.Assume the organisms contain normal double-stranded DNA and predict the composition of the other bases.

-sample A contains 21.1% Thymine

%A

-sample B contains 27.1% Thymine

%A

-number

%G

-number

%G

-number

%C

-number

%C

Both samples are then denatured to remove the secondary structure.which will have the higher temperature to denature A or B ?

Answer 1

Sample A contains 21.1% thymine which means it contains the same percentage of adenine.

So, the sample contains 21.1% adenine and 21.1 % thymine. The sum of both of them is 21.1+ 21.1= 42.2 %.

The rest of the sample contains guanine and cytosine. The amount of guanine and cytosine is 100- 42.2=57.8 %. The guanine percentage is 28.9% and same is the cytosine.

The sample B contains 27.1% of thymine which means adenine percentage is also the same. The total of adenine and thymine is 54.2%

The guanine and cytosine percentage is 45.8 % which means 22.9% each.

The GC content in the sample B is 45.8% and AT content is 54.2%

The GC content in the Sample A is 57.8% and AT content is 42.2 %

The sample B will require more energy to denature the sample than sample A because it has more GC content in it. This is because the GC has 3 hydrogen bonds in between them and AT has two hydrogen bonds between them.

Answer 2

In sample A,

As A comprises 21.1% thymine, so A = T = 21.1%

Also, A+T = 42.2%

Therefore, G+C = 57.8%

So, G = 57.8/2 = 28.9%

Also, G = C = 28.9%

In sample B,

Sample B comprises 27.1 % thymine, therefore A = T = 27.1%

Also, A+T = 54.2%

Thus, G+C = 45.8%

So, G = 45.8/2 = 22.9%

Also, G = C = 22.9%

Since, the content of GC is more in the sample A, that is, 57.8 %. Thus, the sample A exhibits higher temperature to denature in comparison to B, which is 45.8%.