Problem 94 - Chemistry: The Central Science

Question

Can a DNA strand bind to a complementary RNA strand? Explain.

Step-by-Step Solution

Answer

Yes, a DNA strand can bind to a complementary RNA strand, forming a DNA-RNA hybrid. This interaction follows the Watson-Crick base pairing rules, with adenine (A) binding to uracil (U) and cytosine (C) binding to guanine (G) in the RNA strand. The formation of DNA-RNA hybrids is a crucial aspect of various cellular processes, including transcription.

Step 1: Understand DNA and RNA structure

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are both nucleic acids that carry genetic information in cells. DNA is double-stranded, helical molecule consisting of two complementary strands, and RNA is a single-stranded molecule. The primary difference between DNA and RNA is the sugar molecule in their backbone: DNA has deoxyribose sugar while RNA has ribose sugar. Additionally, the nucleotide bases in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T), whereas in RNA, thymine is replaced by uracil (U).

Step 2: Complementary base pairing rules

When DNA and RNA strands interact, they follow Watson-Crick base pairing rules. In this type of base pairing, adenine (A) binds to thymine (T) or uracil (U) and cytosine (C) binds to guanine (G). DNA strands follow the A-T and C-G pairing rules, while RNA follows the A-U and C-G pairing rules.

Step 3: Formation of DNA-RNA hybrids

DNA can bind to a complementary RNA strand, forming a DNA-RNA hybrid. In this case, the DNA strand will interact with its complementary RNA strand through hydrogen bonds. The complementary base pairing between DNA and RNA will follow the same rules as mentioned earlier: A with U and C with G. The formation of such DNA-RNA hybrids occurs during various cellular processes, including transcription, where an RNA transcript is synthesized from a DNA template.

Step 4: Conclusion

Yes, a DNA strand can bind to a complementary RNA strand. This binding follows the same Watson-Crick base pairing rules as within DNA (A-T and C-G) and within RNA (A-U and C-G), allowing for the formation of DNA-RNA hybrids during various cellular processes, such as transcription.