Monday, April 2, 2012

Biological molecules Wksht B - Structured Q2

When checking through your Biological Molecules Tutorial, I found that many of you do not know how to phrase your answer to the above-named question. Since this is an important Q (data analysis Q), I think that it is crucial for you to understand how to phrase your answer. You will be seeing many more of these data analysis Q in future. As such, when you get your worksheets back, please check against your own tutorial worksheet and see that you got the answer below:

Q) DESCRIBE [D] and EXPLAIN [E] the data obtained (you should have two MEANINGFUL observations).

A)
[D1] The ratio of A:T and C:G is 1:1 in BOTH species X and Y.
[E1] This is because according to Chargaff's complementary base pairing rule, Adenine (A) always pairs with Thymine (T), while Cytosine (C) always pairs with Guanine (G).

[D2] In species X, the (C+G) content is 4 times higher than the (A+T) content, whereas in Species Y, both such contents are about the same.
[E2] This is because A and T forms two hydrogen bonds while C and G forms three hydrogen bonds,
making a C-G base pair stronger than a A-T base pair.
Since high temperatures denatures DNA, species Y that lives in a hot spring under high temperatures possesses higher C-G content to ensure stability of its DNA.

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