Suppose you know that the sequence of bases on one DNA strand (one side of the DNA ladder) is AGCTCAG. What is the sequence of the bases on the opposite strand?
The correct answer and explanation is:
The sequence of the bases on the opposite strand of DNA is TCGAGTC.
DNA consists of two strands that are complementary to each other, meaning that the bases pair in specific ways. The four nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G). The base pairing follows two key rules:
- Adenine (A) always pairs with thymine (T).
- Cytosine (C) always pairs with guanine (G).
Given the sequence on one strand is AGCTCAG, the opposite strand is constructed by pairing each base with its complementary partner. Let’s break it down:
- A (adenine) pairs with T (thymine).
- G (guanine) pairs with C (cytosine).
- C (cytosine) pairs with G (guanine).
- T (thymine) pairs with A (adenine).
- C (cytosine) pairs with G (guanine).
- A (adenine) pairs with T (thymine).
- G (guanine) pairs with C (cytosine).
Thus, the sequence on the opposite strand will be TCGAGTC. This complementary pairing ensures that the DNA can be accurately replicated and transcribed, maintaining genetic integrity across generations.
This pairing mechanism is essential for DNA replication. During cell division, the two strands of DNA separate, and each strand serves as a template for the formation of a new complementary strand. This process ensures that the genetic code is faithfully passed on to daughter cells.