Multiple Choice
Which nitrogenous base is not found in DNA?
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7. DNA and Chromosome Structure
DNA Structure
Multiple Choice
In DNA structure, what is the name of the “twisted ladder” shape formed by two antiparallel strands?
A
Single helix
B
Triple helix
C
Beta-pleated sheet
D
Double helix
Verified step by step guidance1
Understand that DNA is composed of two strands that run in opposite directions, which is referred to as antiparallel strands.
Recognize that the structure formed by these two strands is not a simple straight ladder but is twisted.
Recall that the term used to describe this twisted ladder shape in DNA is the 'double helix'.
Note that 'single helix' and 'triple helix' refer to different structures, and 'beta-pleated sheet' is a protein secondary structure, not related to DNA.
Therefore, the correct name for the twisted ladder shape of DNA with two antiparallel strands is the 'double helix'.
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