Problem 83 - Chemistry Matter and Change

Question

DNA Replication One strand in a DNA molecule has the following base sequence. What is the base sequence of the other strand in the DNA molecule? $$C-C-G-T-G-G-A-C-A-T-T-A$$

Step-by-Step Solution

Answer

The base sequence of the other strand in the DNA molecule is \(G-G-C-A-C-C-T-G-T-A-A-T\).

Step 1: Identify the base sequence of the given strand

The given strand has the following base sequence: C-C-G-T-G-G-A-C-A-T-T-A

Step 2: Apply the base-pairing rules to each base in the sequence

Remember that A pairs with T and C pairs with G. Go through each base in the sequence and identify its complementary base. C -> G C -> G G -> C T -> A G -> C G -> C A -> T C -> G A -> T T -> A T -> A A -> T

Step 3: Write down the base sequence of the other strand

By following the base-pairing rules, the base sequence of the other strand in the DNA molecule is: \(G-G-C-A-C-C-T-G-T-A-A-T\).

Key Concepts

Base-Pairing Rules

Understanding the principle of base-pairing rules is crucial in comprehending the mechanisms of DNA replication. The structure of DNA was uncovered by scientists James Watson and Francis Crick, revealing that DNA consists of two strands forming a double helix.

At the heart of these strands lies the principle of base-pairing rules, which are guidelines that dictate how nucleotide bases pair together. The nucleotide bases are adenine (A), thymine (T), guanine (G), and cytosine (C).

Following the base-pairing rules:

• Adenine (A) always pairs with thymine (T)
• Guanine (G) always pairs with cytosine (C)

These rules ensure that the DNA strands are complementary to each other. In other words, wherever there is an A on one strand, there must be a T on the other, and wherever there is a G on one strand, a C will be on its opposite. This pairing is held together by hydrogen bonds and is foundational for DNA being able to replicate accurately.

Complementary Base Pairs

The concept of complementary base pairs is intertwined with the base-pairing rules and is essential for the structure and function of DNA. A pair of nucleotide bases, one from each strand of the DNA, that interacts through hydrogen bonding is what we refer to as complementary base pairs.

It's not just a matter of pairing, however; the specificity of base pairs is a fine example of molecular recognition. This precision ensures that only the correct bases are paired, which is vital for DNA's function in encoding genetic information. When one strand has an adenine (A), it will pair up with thymine (T) on the other strand, and similarly, a cytosine (C) will find its partner in guanine (G) on the complementary strand.

Through these specific interactions, two strands of DNA hold together forming the iconic double helix structure, and during DNA replication, the enzyme DNA polymerase utilizes this principle to build a new strand by 'reading' the existing one and adding the appropriate complementary base at each step.

Nucleotide Sequence

The nucleotide sequence represents the order in which nucleotide bases are arranged along a single strand of DNA. This sequence is what carries the genetic information that can determine traits in living organisms -- from eye color to predisposition to certain diseases.

The understanding of a nucleotide sequence comes into practical application especially during the process of DNA replication. Each nucleotide in the sequence holds a specific place and dictates the composition of the subsequent complementary strand. When the sequence of one strand is established, such as the exercise example given as: (C-C-G-T-G-G-A-C-A-T-T-A), one can predict the sequence of the new strand by applying base-pairing rules.

In context, the original sequence serves as a template, and the resulting sequence is: (G-G-C-A-C-C-T-G-T-A-A-T), by adding the correct complementary bases. This precision ensures that each new cell will have the exact same genetic information as the one it descended from, which is an essential feature of life.