Question

The monomers of proteins are ___________, and these are linked by polar covalent bonds commonly referred to as ___________. a. nucleotides, peptide bonds b. amino acids, ester bonds c. hydroxyl groups, ester bonds d. amino acids, peptide bonds e. monosaccharides, glycosidic linkages

Short answer

The monomers of proteins are amino acids, and these are linked by a type of polar covalent bonds known as peptide bonds. Therefore, the correct answer is d. amino acids, peptide bonds.

Step-by-step solution

Understanding the monomer of proteins

In proteins, the monomer unit is called an amino acid. Amino acids are organic molecules that are made up of an amino group, a carboxyl group and a unique side chain. There are 20 different types of amino acids that can be combined to make a protein.

Understanding the nature of bonds in proteins

The monomer units in proteins, i.e., the amino acids, are linked by a specific type of bond called a peptide bond. A peptide bond is a covalent bond that forms between two amino acids when the carboxyl group of one amino acid reacts with the amino group of the other amino acid.

Analyzing the options

Based on the above understanding, we can analyze the options and see which one fits best. Options a, b and c do not fit because the monomers are not called nucleotides, nor are they bonded by ester bonds or are made of hydroxyl groups. Only options d) and e) mention amino acids, but e) is incorrect because amino acids are not bonded by glycosidic linkages. Therefore, the correct answer is d) 'amino acids, peptide bonds'.

Key concepts

Amino Acids

Amino acids are the building blocks of proteins, each with a fundamental structure comprising an amino group (NH2), a carboxyl group (COOH), and a distinctive side chain, or 'R group', which determines the amino acid's properties. There are 20 standard amino acids that our bodies use to synthesize proteins.

The structure of amino acids enables them to play critical roles in various biological processes. Not only do they construct proteins, but they also function in neurotransmission and as metabolic intermediates. When students learn about amino acids, they uncover the fascinating diversity of these molecules; although constructed from the same basic elements, the nature of the 'R group' makes each one unique, influencing the final three-dimensional structure and function of the protein.

Peptide Bonds

Peptide bonds are the chemical linkages that hold amino acids together in proteins. They are formed through a dehydration synthesis reaction, a process that involves the removal of a water molecule. Specifically, the carboxyl group of one amino acid reacts with the amino group of another.

This results in the formation of a covalent bond, a type of stable link that shares electrons between atoms, ensuring the protein's structure remains intact. The peptide bond is quite strong due to its resonance stability, a topic often emphasized in advanced biology or organic chemistry courses. Understanding the formation and properties of peptide bonds is crucial for students as these are the ties that shape the protein's primary structure and define the sequence of amino acids. It's like a string of beads where each bead is an amino acid, and the string itself is the series of peptide bonds connecting them.

Protein Monomers

A protein monomer refers to the single, simplest unit from which a protein is constructed, which is the amino acid. Considering proteins as polymers, their monomers are essential for dictating the protein's final structure and function. To understand protein monomers, learners should think about how single building blocks can be used to build complex structures—like using different shapes of Lego blocks to build a model.

As students delve into the study of proteins, they'll discover that the sequence and nature of these protein monomers not only determine the shape of the protein but also affect its ability to interact with other molecules. The sequence of amino acids, or protein monomers, creates a 'language' with which the body can construct countless varieties of proteins, each tailored for a specific task. In summary, the protein monomers are like the alphabet of life, a simple set of letters that can craft an infinite array of biological stories.