Question

In Section 22.6, three important classes of biologically important natural polymers are discussed. What are the three classes, what are the monomers used to form the polymers, and why are they biologically important?

Short answer

The three classes of biologically important natural polymers are carbohydrates, proteins, and nucleic acids. Carbohydrates consist of monomer units called monosaccharides, proteins consist of monomer units called amino acids, and nucleic acids consist of monomer units called nucleotides. These polymers are vital for various biological processes: carbohydrates provide energy and structural support, proteins play roles in biochemical reactions and cellular functions, and nucleic acids store and transmit genetic information and guide protein synthesis.

Step-by-step solution

Class 1: Carbohydrates

Carbohydrates are a class of biologically important polymers consisting of monomer units called monosaccharides. Monosaccharides are simple sugars such as glucose, fructose, and galactose. These polymers can be classified as disaccharides, oligosaccharides, or polysaccharides. Carbohydrates play crucial roles in living organisms: they serve as an essential source of energy, contribute to the structural components of cells, and function as cell-to-cell signaling molecules.

Class 2: Proteins

Proteins are another class of biologically important polymers. These natural polymers are comprised of monomer units called amino acids. There are 20 standard amino acids that can combine to form a vast array of proteins structures via peptide bonds. Proteins play a critical role in every biological process, including catalyzing biochemical reactions, providing structural support, facilitating transport of molecules across cell membranes, and coordinating various processes within the body through signaling and regulation.

Class 3: Nucleic Acids

Nucleic acids are the third class of biologically important natural polymers. Nucleic acids are made up of monomer units called nucleotides, which consist of a nitrogenous base, a five-carbon sugar (either ribose or deoxyribose), and a phosphate group. There are two types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA stores genetic information and serves as the blueprint for synthesizing proteins, while RNA is involved in various cellular processes, including the synthesis of proteins from DNA. Nucleic acids are essential for the storage and transmission of genetic information, protein synthesis, and regulation of gene expression. In conclusion, carbohydrates, proteins, and nucleic acids are the three classes of biologically important natural polymers. Carbohydrates serve as energy sources and structural components, proteins participate in a wide range of cellular processes and functions, and nucleic acids store and transmit genetic information and direct protein synthesis.

Key concepts

Carbohydrates

Carbohydrates are key players in the biological world, acting as natural polymers that are fundamental to life. The building blocks, or monomers, of carbohydrates are known as monosaccharides. Think of these as simple sugars, with common examples being glucose, fructose, and galactose.

These monosaccharides can combine to form complex chains, classified as disaccharides, oligosaccharides, or polysaccharides, depending on the number of sugar units linked.

Carbohydrates serve several important functions:

• They are a primary source of energy for cells, fueling metabolic processes.
• They help to build cellular structures, contributing to the integrity and function of cells.
• They act as signaling molecules in cell-to-cell communication, essential for biological interactions.

Hence, carbohydrates are vital for both the energy supply and structural maintenance within living organisms.

Proteins

Proteins are versatile natural polymers made from monomers called amino acids. There are 20 different amino acids that can combine in numerous ways to form various proteins through peptide bonds. The diversity of proteins reflects the unique sequence and arrangement of these amino acids.

Proteins play a major role in almost every biological process, performing functions such as:

• Catalyzing biochemical reactions as enzymes.
• Providing structural support to cells and tissues.
• Facilitating the transport of substances across cell membranes.
• Coordinating cellular activities through signaling pathways and regulatory mechanisms.

Considering these roles, proteins are indispensable for maintaining life processes, from cellular metabolism to organismal development.

Nucleic Acids

Nucleic acids, another class of vital natural polymers, consist of monomers called nucleotides. Each nucleotide contains three components: a nitrogenous base, a five-carbon sugar (ribose in RNA or deoxyribose in DNA), and a phosphate group.

There are two primary types of nucleic acids: DNA and RNA.

• DNA (deoxyribonucleic acid) serves as the repository of genetic information, embodying the blueprint for protein synthesis.
• RNA (ribonucleic acid) supports various cellular tasks, including the synthesis of proteins guided by the information in DNA.

Nucleic acids are thus essential for the storage and transmission of genetic information, as well as for facilitating the expression of genes into functional proteins.