Question

Complementary base pairing a. involves \(\mathrm{T}\), \(\mathrm{A}\), \(\mathrm{G}\), C. b. is necessary to replication. c. uses hydrogen bonds. d. All of these are correct.

Short answer

Complementary base pairing involves Adenine (A) pairing with Thymine (T), and Guanine (G) pairing with Cytosine (C) in DNA (option a). It is essential during DNA replication as it ensures accurate passing of genetic information to new cells (option b). The base pairs are held together by hydrogen bonds, with A-T having two hydrogen bonds and G-C having three hydrogen bonds (option c). Therefore, the correct answer is d. All of these are correct.

Step-by-step solution

Option a: Involves T, A, G, C

Complementary base pairing involves Adenine (A) pairing with Thymine (T), and Guanine (G) pairing with Cytosine (C) in DNA. So, option (a) is correct.

Option b: Necessary to replication

Complementary base pairing is essential during DNA replication, as each strand of the original DNA molecule serves as a template for the production of its complementary strand. This ensures that genetic information is accurately passed on to new cells. So, option (b) is correct.

Option c: Uses hydrogen bonds

The complementary base pairs, A with T and G with C, are held together by hydrogen bonds. A-T pairs have two hydrogen bonds, whereas G-C pairs have three hydrogen bonds, providing the specific interactions necessary for maintaining the DNA double helix structure. So, option (c) is correct. Since all the options (a, b, and c) are correct regarding complementary base pairing in DNA, the correct answer is:

Correct answer

d. All of these are correct.

Key concepts

DNA Replication

Understanding DNA replication is fundamental for grasping how genetic information is duplicated to maintain life. Replication is a sophisticated cellular mechanism that ensures every time a cell divides, each new cell inherits an exact copy of the parent cell's DNA. This miraculous process begins at specific locations in the DNA molecule called origins of replication.

The unwinding of the double helix, facilitated by enzymes known as helicases, exposes the strands for replication. Another enzyme, DNA polymerase, adds nucleotides to the exposed bases in accordance with the rules of complementary base pairing: Adenine (A) always pairs with Thymine (T) and Guanine (G) always pairs with Cytosine (C). Each of the original strands serves as a template for the creation of a new complementary strand, a process often likened to unzipping and zipping a zipper.

What's fascinating is that DNA replication proceeds in a semi-conservative manner, which means that each new DNA molecule consists of one original and one newly synthesized strand—preserving genetic continuity through generations.

Hydrogen Bonds in DNA

The stability and specificity of the DNA double helix stem from hydrogen bonds between complementary nucleotide bases. These are weak chemical bonds—easier to break than covalent bonds, yet strong enough to stably maintain the DNA structure. Importantly, these bonds allow for the double helix to be 'unzipped' during replication.

Each A-T pair is linked by two hydrogen bonds, while each G-C pair is connected by three. This discrepancy not only contributes to the specificity of base pairing but also affects the overall stability of the DNA molecule; regions with high G-C content are more tightly bonded than those rich in A-T. During replication, the enzyme DNA polymerase 'reads' the exposed bases and brings in the correct complementary nucleotides. Thus, hydrogen bonds are a key element in ensuring the high-fidelity transfer of genetic information.

Genetic Information Transmission

The continuity of life depends on the precise transmission of genetic information from one generation to the next. This biological heritage, encoded in the DNA's sequence of nucleotides, dictates everything from the color of our eyes to our susceptibility to certain diseases.

Genetic information is transmitted through several key processes: replication, transcription, and translation. Replication ensures the DNA is accurately copied before cell division; transcription converts DNA's code into messenger RNA (mRNA), which is then used as a template in translation to build proteins—the workhorses of the cell. All these stages rely on complementary base pairing to ensure that the information carried in the DNA sequence is translated into the correct sequence of amino acids in proteins. Furthermore, meiosis and sexual reproduction shuffle the genetic deck of cards, contributing to genetic diversity critical for species survival.