Question

Write the DNA complement for \(5^{\prime}\)-ACCGTTAAT- \(3^{\prime}\). Be certain to label which is the \(5^{\prime}\) end and which is the \(3^{\prime}\) end of the complement strand.

Short answer

Answer: The DNA complement for the given strand is \(5^{\prime}\)-TGGCAATTG-\(3^{\prime}\).

Step-by-step solution

Understand the base pairing rules in DNA

In DNA, the bases pair according to Chargaff's rules, which state that Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G).

Write the complementary pairs for each base in the given sequence

Follow the base pairing rules explained earlier to find the complement of each base in the original sequence: A -> T C -> G C -> G G -> C T -> A T -> A A -> T A -> T T -> A

Write the complement strand from \(5^{\prime}\) end to \(3^{\prime}\) end.

Arrange the complement bases found in step 2 in the same order from left to right (maintaining the direction from \(5^{\prime}\) end to \(3^{\prime}\) end). The complementary strand for the given sequence is \(5^{\prime}\)-TGGCAATTG-\(3^{\prime}\).

Key concepts

Chargaff's Rules: The Basis of DNA Complementation

When studying DNA complementation, an essential concept to grasp is Chargaff's rules. These rules are named after Erwin Chargaff, who made a pivotal discovery in the early 1950s. He observed that in DNA, the amount of adenine (A) always equals the amount of thymine (T), and the amount of guanine (G) is always equal to the amount of cytosine (C). This is because A pairs with T and G pairs with C in the DNA structure.

Chargaff's rules form the foundation for understanding how DNA strands bond together to form a double helix. Each strand of DNA can serve as a template for creating its complement due to these pairing rules. If you know the sequence of bases on one strand, you can use Chargaff's rules to determine the sequence of the opposite strand. For instance, a sequence of 5'‑ACCGTTAAT‑3' would imply a complementary strand with the sequence 5'‑TGGCAATTG‑3', because A pairs with T and G pairs with C, according to Chargaff's rules.

This insight not only assists in textbook exercises like the provided one but also underlies DNA replication and transcription processes within living cells.

Base Pairing: The Heart of Genetic Codes

Base pairing is a fundamental concept in understanding DNA structure and function. It's the 'heart' of the genetic code. In the DNA molecule, base pairing refers to the rules by which nucleotide bases pair together through hydrogen bonds. As mentioned in the exercise solution, adenine (A) always pairs with thymine (T), and cytosine (C) pairs with guanine (G).

It's crucial to remember that base pairing is specific; A will not pair with G, nor will C pair with T. The specificity is due to the size, shape, and chemical structure of each base. Additionally, each pair forms a particular number of hydrogen bonds, with A and T forming two hydrogen bonds and C and G forming three, providing a level of stability to the DNA structure.

Understanding base pairing is key for a variety of genetic processes, including DNA replication and RNA transcription, and is an essential step in solving exercises involving DNA sequencing or complementation, like the one we're addressing. This pairing mechanism is why the complement of 5'‑ACCGTTAAT‑3' becomes 5'‑TGGCAATTG‑3'.

Nucleotide Sequence: Deciphering the Language of Genes

The nucleotide sequence is essentially the language of genes; it's a precise arrangement of nucleotides—adenine (A), thymine (T), guanine (G), and cytosine (C)—along a DNA strand that conveys genetic information. A nucleotide sequence is read in a specific direction, from the 5' end to the 3' end, which denotes the carbon numbers in the DNA's sugar backbone.

Interpreting the nucleotide sequence is critical for many facets of genetics and molecular biology. It's the variance in these sequences that accounts for the diverse traits and functions observed in living organisms. In relation to our exercise, being able to identify and write down a nucleotide sequence is fundamental. As mentioned in the exercise solution, accurately identifying the complement sequence requires following the base pairing rule, considering sequence directionality and clearly labeling the 5' and 3' ends.

Ensuring the complement is written from the 5' to 3' end, as in the solution provided (5'‑TGGCAATTG‑3'), is vital because it mirrors the way DNA is naturally synthesized and replicated, following the anti-parallel arrangement of the double helix. The sequence precision also comes into play in DNA sequencing technologies, polymerase chain reactions (PCR), and various biotechnological applications.