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Multiple Choice
The two strands of a DNA double helix are antiparallel. This means that __________.
A
the two strands are mirror images
B
only one of the two strands can be used as a template for replication because DNA polymerase only works in one direction
C
one strand is actually composed of RNA
D
they both run in the 3' to 5' direction
E
one strand runs in the 5' to 3' direction and the other runs in the 3' to 5' direction
Verified step by step guidance
1
Understand the structure of DNA: DNA is composed of two strands that form a double helix. Each strand is made up of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base.
Recognize the concept of antiparallel orientation: In the DNA double helix, the two strands run in opposite directions. This is referred to as antiparallel orientation.
Identify the directionality of DNA strands: Each DNA strand has a directionality, which is determined by the orientation of the sugar-phosphate backbone. One end of the strand is the 5' end, and the other is the 3' end.
Clarify the antiparallel nature: In an antiparallel arrangement, one strand runs from the 5' to the 3' direction, while the complementary strand runs from the 3' to the 5' direction.
Conclude with the correct understanding: The antiparallel nature of DNA is crucial for replication and other cellular processes, as it allows enzymes like DNA polymerase to function properly, synthesizing new strands in the 5' to 3' direction.