Which of the following strands are antiparallel?Group of answer choices5’──3’3’──5’3’──5’3’──5’5’──3’5’──3’

1. Break Down the Problem

To determine which strands are antiparallel, we need to understand the orientation of each strand. Antiparallel strands mean that one strand runs in the 5' to 3' direction, and the other strand runs in the 3' to 5' direction.

2. Relevant Concepts

• 5' and 3' Ends: In biochemistry, the terms 5' (five prime) and 3' (three prime) refer to the carbon numbers in the DNA's sugar backbone. The 5' end has a phosphate group, while the 3' end has a hydroxyl group.
• Antiparallel Orientation: For two strands to be complementary and antiparallel, one must run 5' to 3' and the other must run 3' to 5'.

3. Analysis and Detail

• Option 1 (5’──3’ and 3’──5’): These strands are antiparallel.
• Option 2 (3’──5’ and 5’──3’): These strands are also antiparallel, the same as Option 1 but in reverse order.
• Option 3 (3’──5’ and 3’──5’): These strands run in the same direction and are therefore not antiparallel.
• Option 4 (5’──3’ and 5’──3’): These strands also run in the same direction and are not antiparallel.
• Option 5 (5’──3’ and 3’──5’): Same as Option 1, those strands are complementary and antiparallel.

4. Verify and Summarize

Options that are antiparallel:

• 5’──3’ paired with 3'──5' (found in several choices) are antiparallel.
• The strands 3’──5’ and 5’──3’ are essentially the same in terms of genetic complementarity.

Final Answer

The strands that are antiparallel are 5’──3’ and 3’──5’, which appear in multiple options.