Multiple Choice
Both DNA and RNA are made of repeating subunits called which of the following?
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7. DNA and Chromosome Structure
DNA Structure
Multiple Choice
In the B-form DNA double helix, approximately how many times longer is one helical turn than the diameter (width) of the helix?
A
About 1.6 times longer
B
About 17 times longer
C
About 3.4 times longer
D
About 34 times longer
Verified step by step guidance1
Recall the structural parameters of B-form DNA: one helical turn corresponds to a length of approximately 3.4 nanometers (nm), and the diameter (width) of the helix is about 2 nanometers (nm).
To find how many times longer one helical turn is compared to the diameter, set up the ratio: \(\text{Ratio} = \frac{\text{Length of one helical turn}}{\text{Diameter of helix}}\).
Substitute the known values into the ratio: \(\text{Ratio} = \frac{3.4\ \text{nm}}{2\ \text{nm}}\).
Calculate the ratio to determine how many times longer the helical turn is relative to the diameter.
Interpret the result to select the closest answer choice from the options provided.
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