Question

If the sequence \(\mathrm{T}-\mathrm{A}-\mathrm{C}-\mathrm{C}-\mathrm{G}-\mathrm{A}\) appeared on one strand of DNA, what sequence would appear opposite it on the other strand?

Short answer

The complementary sequence is A-T-G-G-C-T.

Step-by-step solution

Understanding DNA Base Pairing

DNA consists of two strands that form a double helix. The basic rule for pairing is that Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G). This complementary base pairing ensures that the DNA structure is consistent and allows for replication.

Identify Base Pairing for Each Nucleotide

Given the sequence T-A-C-C-G-A, we will determine the complementary base for each nucleotide: T pairs with A, A pairs with T, C pairs with G, C pairs with G, G pairs with C, and A pairs with T.

Construct the Complementary Sequence

Based on the base-pairing rules, construct the complementary sequence by replacing each nucleotide with its pair. The sequence for T-A-C-C-G-A becomes A-T-G-G-C-T.

Key concepts

Nucleotide Sequences

Nucleotides are the building blocks of DNA and are composed of three parts: a phosphate group, a deoxyribose sugar, and a nitrogenous base. Each DNA nucleotide contains one of four possible nitrogenous bases: Adenine (A), Thymine (T), Cytosine (C), or Guanine (G). These nucleotides are linked together in a specific order, forming long chains that make up the DNA molecule. The sequence of these bases on a DNA strand is crucial because it encodes genetic information necessary for cell functioning and development. Understanding nucleotide sequences is important because even small changes can lead to significant genetic variations or mutations.

• Nucleotide: A unit composed of a sugar, a phosphate group, and a nitrogenous base.
• Base sequence: The order of bases in a DNA strand, sensitive to alterations.
• Genetic Information: Encoded within the sequence, vital for cellular functions.

Thus, by analyzing and interpreting these sequences, scientists can understand and manipulate genetic blueprints.

Complementary Strands

DNA's double helix consists of two strands that are complementary to each other. The principle of complementary base pairing makes this structure possible. According to it, Adenine always pairs with Thymine, and Cytosine always pairs with Guanine. This compatibility ensures that each DNA strand contains all the information needed to reconstruct the other strand. Complementary strands mean that for a DNA sequence, there is a corresponding sequence on its opposite strand. This relationship is vital during DNA replication and repair, as each strand serves as a template for generating its complement.

• Complementary Base Pairing: A with T, and C with G.
• Double Helix: The shape formed by two interconnected, complementary strands.
• Template Strand: A single DNA strand used in DNA replication as a guide to form the new complementary strand.

Overall, the notion of complementary strands is fundamental to genetic processes and stability.

DNA Structure

The structure of DNA is a twisted ladder known as a double helix. Its outer sides are made of alternating sugar (deoxyribose) and phosphate groups, which form the backbone of the DNA. Between these backbones are pairs of nitrogenous bases, which connect like rungs on a ladder. These bases are held together by hydrogen bonds. This orderly structure supports the storage and transmission of genetic information. It remains remarkably stable yet flexible enough to allow for replication and transcription.

• Double Helix: Characteristic helical shape of DNA.
• Sugar-Phosphate Backbone: The supportive framework of the DNA strand.
• Hydrogen Bonds: Weak bonds allowing base interaction and separation during replication.

The DNA structure is a masterpiece of natural engineering, balancing complexity and functionality to sustain life.