Question

Three important biomolecules are depicted in their ionized forms at physiological \(\mathrm{pH}\). Identify the chemical constituents that are part of each molecule. a. Guanosine triphosphate (GTP), an energy-rich nucleotide that serves as a precursor to RNA:

Short answer

GTP contains guanine, ribose sugar, and three phosphate groups.

Step-by-step solution

Identify the Parts of GTP

Guanosine triphosphate (GTP) is composed of several chemical constituents. It includes a guanine base, a ribose sugar, and three phosphate groups. At physiological pH, these components are ionized: the phosphate groups bear negative charges, and the guanine base exists in its physiological form.

Guanine Base

The first part of GTP is the guanine base, which is a purine base. Guanine has fused rings with a total of five nitrogen atoms. It is important in forming hydrogen bonds with cytosine in nucleic acids.

Ribose Sugar

The second constituent in GTP is the ribose sugar. Ribose is a five-carbon sugar with a hydroxyl group at the 2' position, distinguishing it from deoxyribose, and is important for forming RNA nucleotides.

Phosphate Groups

The last part of GTP comprises three phosphate groups. These are linked to the 5' carbon of the ribose sugar. They are often referred to as alpha, beta, and gamma phosphates, starting from the sugar. At physiological pH, these phosphates are ionized and negatively charged.

Key concepts

Guanosine Triphosphate (GTP)

Guanosine Triphosphate, commonly abbreviated as GTP, is a crucial molecule in cellular activities. It acts as an energy carrier, similar to ATP but with a specific role in signaling pathways and protein synthesis. GTP is a nucleotide, which means it is made up of three main parts: a guanine base, a ribose sugar, and three phosphate groups. These components together make it an essential player in various biological processes.

GTP is particularly known for its role as a precursor to RNA. During protein synthesis, GTP provides the energy required to form peptide bonds. It's also involved in the regulation of G-proteins, which act as molecular switches inside cells, thus playing a role in various metabolic processes.

Nucleic Acids

Nucleic acids are fundamental biomolecules that carry genetic information. They are polymers made up of monomers known as nucleotides. The two most common forms of nucleic acids are DNA and RNA. DNA holds genetic instructions for the development and functioning of living beings, whereas RNA translates these instructions to synthesize proteins.

Each nucleotide in nucleic acids includes three components: a nitrogenous base (like guanine or adenine), a sugar molecule (either deoxyribose in DNA or ribose in RNA), and phosphate groups. These nucleotides are linked together to form long chains, with the sequence of bases encoding genetic information. This information flow is central to the concepts of genetics and biochemistry.

Phosphate Groups

Phosphate groups are vital parts of molecules like GTP, ATP, and nucleic acids. In GTP, there are three phosphate groups attached to the molecule, referred to as alpha, beta, and gamma phosphates. These phosphates are linked to the 5' carbon of the ribose sugar in GTP.

Phosphate groups are characterized by their ability to be ionized and bear negative charges at physiological pH. This property is key to the function of nucleotide triphosphates, enabling them to store and transfer energy within cells. When these phosphate bonds are broken, energy is released, which cells utilize for numerous biochemical reactions, from muscle contraction to active transport.

Ribose Sugar

Ribose sugar is an essential part of nucleotides, particularly in RNA. It is a five-carbon sugar with a hydroxyl group on the 2' carbon, which is distinctive for ribose compared to deoxyribose in DNA.

This hydroxyl group is crucial because it makes the RNA less stable than DNA, which is why RNA is typically single-stranded. In GTP, ribose connects to both the purine base and the phosphate groups. The presence of ribose in GTP forms the backbone to which the nitrogenous base and the phosphate groups attach, enabling GTP to interact with enzymes and other molecules in biological systems.

Purine Base

Purine bases are one of the two categories of nitrogenous bases found in nucleotides, the building blocks of nucleic acids. Guanine, a purine base, is a key component of GTP. Purines have a distinctive double-ring structure containing nitrogen, which differentiates them from pyrimidines, which have a single-ring structure.

Guanine pairs with cytosine through hydrogen bonds in the structure of nucleic acids, contributing to the stability and fidelity of DNA and RNA. As part of GTP, the guanine base interacts with enzymes and helps in processes like protein synthesis and cellular signaling, underscoring its importance in maintaining cellular functions.