If 16% of the nucleotides in one strand of a DNA molecule contain the base G, what percent of the nucleotides on the complementary strand will also contain the base G?

Question

A.  16%
B.  8%
C.  34%
D.  32%
E.  Impossible to determine from the information given.

Clarify Question
· What is the key concept addressed by the question?
  · What type of thinking is required?
  · What key words does the question contain?
 
Gather Content
· What do you already know about base pairing in DNA?
 
Consider Possibilities
· What other information is related to the question? Which information is most useful?
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

E.  Impossible to determine from the information given.

Clarify Question
· What is the key concept addressed by the question?
    o This question addresses base pairing in DNA.
  · What type of thinking is required?
    o You need to Analyze the information given, using logic, to dissect the problem and determine the answer.
  · What key words does the question contain?
    o The nucleotides in DNA are the modular units that contain bases adenine, thymine, cytosine, guanine, known as A, T, C, and G, respectively. The complementary strand of DNA is the other strand of the double helix that must base pair with the first strand.
 
Gather Content
· What do you already know about base pairing in DNA?
    o Base pairing in DNA follows the rules: A binds with T, and C binds with G.
    o One strand of the double helix must bind its complementary strand according to these rules.
 
Consider Possibilities
· What other information is related to the question? Which information is most useful?
    o There are only four bases in DNA, so the percentage of those four must add up to 100% of the DNA bases.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
    o What can we infer from the information that one strand contains 16% G?
    o We know that G binds with C on the opposite strand, so we can infer that the complement contains 16% C.
    o What else can we infer? Not much!
    o Try the approach of imagining examples and testing each one.
    o What about a sequence like ATGCGC? In this case, there would be an equal number of Gs in each strand, because the top strand has an equal number of Gs and Cs. But does that have to be the case?     o What about the sequence ATGGGG? Now, the top strand has only Gs, and the bottom strand has only Cs!
    o We know that in the top strand, (A + T + C) + 16% = 100%, and in the bottom strand (A + T + G) + 16% = 100%. But without further information, there is no way to know how much the remaining three bases are contributing to the DNA. The answer is impossible to determine.
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
    o This question required you to Analyze the information given, using logic, to dissect the problem and determine the answer.
    o Did you remember that G binds with C?
    o Did you recognize that Gs and Cs don’t have to equate on the same strand?
    o Did you test examples of your own to analyze possibilites?
    o Could a piece of DNA be all Gs on one strand, and all Cs on another?