38. If a portion of a strand of DNA bases reads 5' AGCTAGCGT 3', what would the sequence of bases on the complementary strand read?
Answer: C
The sequence of bases on the complementary strand would read 3' TCGATCGCA 5'
The complementary strand of DNA is formed by pairing adenine (A) with thymine (T) and cytosine (C) with guanine (G). Therefore, the sequence that complements 5' AGCTAGCGT 3' is 3' TCGATCGCA 5'.
A) 3' AGCTAGCGT 5'
This option repeats the original sequence without providing the correct complementary bases. The correct pairing requires that A pairs with T and C with G, making this option incorrect.
B) 5' UCGAUCGCA 3'
This option contains RNA bases instead of DNA bases, specifically uracil (U) instead of thymine (T). Since the question pertains to a DNA sequence, this option is incorrect.
C) 3' TCGATCGCA 5'
This is the correct answer as it accurately represents the complementary sequence to 5' AGCTAGCGT 3' by matching A with T and C with G, and it is oriented properly from 3' to 5'.
D) 5' TCGUTCGCU 3'
This option incorrectly uses uracil (U) instead of thymine (T) and presents the sequence in the wrong orientation. Therefore, this option is incorrect.
Conclusion
The correct answer, 3' TCGATCGCA 5', accurately reflects the complementary base pairing rules of DNA, where A pairs with T and C pairs with G. All other options either misrepresent the base pairings or do not conform to the DNA structure, confirming that they are incorrect.