Select From the Following List Those Species That Can Be Identified as Molecules.

Learning Objectives

• Identify common elements and structures found in organic molecules
• Explain the concept of isomerism
• Identify examples of functional groups
• Depict the office of functional groups in synthesizing polymers

Clinical Focus: Cristina, Function ane

Cristina is a 16-year-old educatee who visited her doc, complaining about an itchy pare rash. She had a history of allergic episodes. The medico looked at her dominicus-tanned peel and asked her if she switched to a different sunscreen. She said she had, and so the md diagnosed an allergic eczema. The symptoms were balmy so the physician told Cristina to avert using the sunscreen that caused the reaction and prescribed an over-the-counter moisturizing foam to keep her skin hydrated and to assist with itching.

• What kinds of substances would yous wait to find in a moisturizing foam?
• What physical or chemical properties of these substances would assistance alleviate itching and inflammation of the pare?

We'll return to Cristina's example in later pages.

Biochemistry is the discipline that studies the chemical science of life, and its objective is to explain grade and role based on chemical principles. Organic chemistry is the discipline devoted to the written report of carbon-based chemistry, which is the foundation for the study of biomolecules and the discipline of biochemistry. Both biochemistry and organic chemistry are based on the concepts of general chemistry, some of which are presented in Fundamentals of Physics and Chemistry Important to Microbiology.

Elements in Living Cells

The almost arable chemical element in cells is hydrogen (H), followed past carbon (C), oxygen (O), nitrogen (N), phosphorous (P), and sulfur (S). We call these elements macronutrients, and they account for most 99% of the dry weight of cells. Some elements, such as sodium (Na), potassium (K), magnesium (Mg), zinc (Zn), fe (Iron), calcium (Ca), molybdenum (Mo), copper (Cu), cobalt (Co), manganese (Mn), or vanadium (Va), are required by some cells in very pocket-size amounts and are called micronutrients or trace elements. All of these elements are essential to the function of many biochemical reactions, and, therefore, are essential to life.

The 4 almost abundant elements in living matter (C, N, O, and H) have low atomic numbers and are thus light elements capable of forming stiff bonds with other atoms to produce molecules (Figure i). Carbon forms 4 chemical bonds, whereas nitrogen forms iii, oxygen forms two, and hydrogen forms one. When bonded together within molecules, oxygen, sulfur, and nitrogen often have one or more than "lone pairs" of electrons that play important roles in determining many of the molecules' physical and chemical properties (see Fundamentals of Physics and Chemistry Important to Microbiology). These traits in combination allow the formation of a vast number of diverse molecular species necessary to grade the structures and enable the functions of living organisms.

Figure 1. Some common molecules include carbon dioxide, ammonia, and oxygen, which consist of combinations of oxygen atoms (red spheres), carbon atoms (gray spheres), hydrogen atoms (white spheres), or nitrogen atoms (blue spheres).

Living organisms contain inorganic compounds (mainly water and salts; see Fundamentals of Physics and Chemistry Of import to Microbiology) and organic molecules. Organic molecules contain carbon; inorganic compounds do not. Carbon oxides and carbonates are exceptions; they contain carbon only are considered inorganic because they do not contain hydrogen. The atoms of an organic molecule are typically organized around bondage of carbon atoms.

Inorganic compounds make upwardly 1%–i.five% of a living prison cell'south mass. They are small, simple compounds that play important roles in the cell, although they practice not form cell structures. Most of the carbon establish in organic molecules originates from inorganic carbon sources such as carbon dioxide captured via carbon fixation by microorganisms.

Recollect about It

• Describe the most abundant elements in nature.
• What are the differences between organic and inorganic molecules?

Organic Molecules and Isomerism

Organic molecules in organisms are generally larger and more complex than inorganic molecules. Their carbon skeletons are held together by covalent bonds. They form the cells of an organism and perform the chemical reactions that facilitate life. All of these molecules, called biomolecules because they are part of living matter, contain carbon, which is the building cake of life. Carbon is a very unique element in that it has iv valence electrons in its outer orbitals and can form four single covalent bonds with up to four other atoms at the aforementioned fourth dimension (run into Fundamentals of Physics and Chemistry Important to Microbiology). These atoms are usually oxygen, hydrogen, nitrogen, sulfur, phosphorous, and carbon itself; the simplest organic compound is methyl hydride, in which carbon binds but to hydrogen (Figure 2).

Figure 2. A carbon cantlet tin can bond with up to four other atoms. The simplest organic molecule is methyl hydride (CH₄), depicted hither.

Every bit a result of carbon'south unique combination of size and bonding backdrop, carbon atoms can bind together in large numbers, thus producing a chain or carbon skeleton. The carbon skeleton of organic molecules can exist direct, branched, or band shaped (cyclic). Organic molecules are built on chains of carbon atoms of varying lengths; most are typically very long, which allows for a huge number and diverseness of compounds. No other element has the power to form and then many dissimilar molecules of and so many unlike sizes and shapes.

Molecules with the same atomic makeup only dissimilar structural system of atoms are called isomers. The concept of isomerism is very important in chemistry because the construction of a molecule is e'er directly related to its part. Slight changes in the structural arrangements of atoms in a molecule may lead to very different backdrop. Chemists stand for molecules by their structural formula, which is a graphic representation of the molecular structure, showing how the atoms are bundled. Compounds that have identical molecular formulas but differ in the bonding sequence of the atoms are called structural isomers. The monosaccharides, glucose, galactose, and fructose all accept the same molecular formula, C₆H₁₂O₆, simply we can encounter from Effigy 3 that the atoms are bonded together differently.

Glucose, galactose, and fructose accept the aforementioned chemical formula (C_sixH₁₂O_vi), but these structural isomers differ in their physical and chemical properties.

Isomers that differ in the spatial arrangements of atoms are called stereoisomers; ane unique type is enantiomers. The properties of enantiomers were originally discovered by Louis Pasteur in 1848 while using a microscope to analyze crystallized fermentation products of wine. Enantiomers are molecules that have the characteristic of chirality, in which their structures are nonsuperimposable mirror images of each other. Chirality is an important characteristic in many biologically important molecules, equally illustrated past the examples of structural differences in the enantiomeric forms of the monosaccharide glucose or the amino acid alanine (Figure four).

Many organisms are simply able to use one enantiomeric form of certain types of molecules as nutrients and as building blocks to make structures inside a prison cell. Some enantiomeric forms of amino acids have distinctly unlike tastes and smells when consumed as food. For example, L-aspartame, commonly called aspartame, tastes sugariness, whereas D-aspartame is tasteless. Drug enantiomers can take very dissimilar pharmacologic affects. For example, the chemical compound methorphan exists as 2 enantiomers, i of which acts as an antitussive (dextromethorphan, a cough suppressant), whereas the other acts every bit an analgesic (levomethorphan, a drug similar in outcome to codeine).

Figure 4. Enantiomers are stereoisomers that exhibit chirality. Their chemical structures are nonsuperimposable mirror images of each other. (a) D-glucose and Fifty-glucose are monosaccharides that are enantiomers. (b) The enantiomers D-alanine and 50-alanine are enantiomers found in bacterial prison cell walls and man cells, respectively.

Enantiomers are also chosen optical isomers considering they can rotate the plane of polarized light. Some of the crystals Pasteur observed from wine fermentation rotated light clockwise whereas others rotated the light counterclockwise. Today, nosotros denote enantiomers that rotate polarized light clockwise (+) as d forms, and the mirror image of the aforementioned molecule that rotates polarized light counterclockwise (−) equally the 50 form. The d and l labels are derived from the Latin words dexter (on the correct) and laevus (on the left), respectively. These two unlike optical isomers oft accept very dissimilar biological properties and activities. Sure species of molds, yeast, and bacteria, such every bit Rhizopus , Yarrowia , and Lactobacillus spp., respectively, can only metabolize 1 type of optical isomer; the contrary isomer is not suitable as a source of nutrients. Another important reason to exist aware of optical isomers is the therapeutic use of these types of chemicals for drug handling, considering some microorganisms can merely be afflicted by one specific optical isomer.

Think about It

• We say that life is carbon based. What makes carbon and so suitable to be part of all the macromolecules of living organisms?

Biologically Significant Functional Groups

In addition to containing carbon atoms, biomolecules also contain functional groups—groups of atoms within molecules that are categorized past their specific chemical composition and the chemical reactions they perform, regardless of the molecule in which the group is plant. Some of the virtually common functional groups are listed in Table 1. In the formulas, the symbol R stands for "remainder" and represents the remainder of the molecule. R might symbolize merely a single hydrogen atom or information technology may correspond a grouping of many atoms. Notice that some functional groups are relatively elementary, consisting of but one or two atoms, while some comprise two of these simpler functional groups. For example, a carbonyl group is a functional group composed of a carbon atom double bonded to an oxygen cantlet: C=O. Information technology is nowadays in several classes of organic compounds as part of larger functional groups such as ketones, aldehydes, carboxylic acids, and amides. In ketones, the carbonyl is present as an internal group, whereas in aldehydes it is a concluding group.

Tabular array one. Mutual Functional Groups Found in Biomolecules
Name	Functional Group	Compounds
Aldehyde		Carbohydrates
Amine		Proteins
Amino		Amino acids and proteins
Carbonyl		Ketones, aldehydes, carboxylic acids, amides
Carboxylic acid		Amino acids, proteins, and fatty acids
Ester		Lipids and nucleic acids
Ether		Disaccharides, polysaccharides, and lipids
Hydroxyl		Alcohols, monosaccharides, amino acids, and nucleic acids
Ketone		Carbohydrates
Methyl		Methylated compounds such as methyl alcohols and methyl esters
Phosphate		Nucleic acids, phospholipids and ATP
Sulfhydryl		Amino acids and proteins
*Functional groups are represented in pink. Ketone and aldehyde both incorporate a carbonyl group, highlighted in blue.

Macromolecules

Carbon chains grade the skeletons of most organic molecules. Functional groups combine with the chain to grade biomolecules. Because these biomolecules are typically big, we call them macromolecules. Many biologically relevant macromolecules are formed by linking together a great number of identical, or very similar, smaller organic molecules. The smaller molecules deed as building blocks and are called monomers, and the macromolecules that result from their linkage are called polymers. Cells and cell structures include four main groups of carbon-containing macromolecules: polysaccharides, proteins, lipids, and nucleic acids. The first three groups of molecules will be studied throughout this chapter. The biochemistry of nucleic acids volition be discussed in Biochemistry of the Genome.

Of the many possible ways that monomers may exist combined to yield polymers, one common approach encountered in the germination of biological macromolecules is aridity synthesis. In this chemical reaction, monomer molecules bind end to end in a process that results in the germination of water molecules equally a byproduct:

[latex]{\text{H}-\text{monomer}-\text{OH}+\text{H}-\text{monomer}-\text{OH}}\longrightarrow{\text{H}-\text{monomer}-\text{monomer}-\text{OH}+\text{H}_{2}\text{O}}[/latex]

Effigy 5 shows dehydration synthesis of glucose binding together to form maltose and a h2o molecule. Table 2 summarizes macromolecules and some of their functions.

Figure 5. In this aridity synthesis reaction, ii molecules of glucose are linked together to course maltose. In the process, a h2o molecule is formed.

Tabular array ii. Some Functions of Macromolecules
Macromolecule	Functions
Carbohydrates	Energy storage, receptors, food, structural role in plants, fungal jail cell walls, exoskeletons of insects
Lipids	Free energy storage, membrane construction, insulation, hormones, pigments
Nucleic acids	Storage and transfer of genetic data
Proteins	Enzymes, structure, receptors, transport, structural role in the cytoskeleton of a cell and the extracellular matrix

Think almost It

• What is the byproduct of a dehydration synthesis reaction?

Fundamental Concepts and Summary

• The about abundant elements in cells are hydrogen, carbon, oxygen, nitrogen, phosphorus, and sulfur.
• Life is carbon based. Each carbon atom can demark to another one producing a carbon skeleton that tin be straight, branched, or band shaped.
• The same numbers and types of atoms may bond together in dissimilar means to yield unlike molecules called isomers. Isomers may differ in the bonding sequence of their atoms (structural isomers) or in the spatial arrangement of atoms whose bonding sequences are the same (stereoisomers), and their physical and chemical properties may vary slightly or drastically.
• Functional groups confer specific chemical properties to molecules bearing them. Common functional groups in biomolecules are hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl.
• Macromolecules are polymers assembled from private units, the monomers, which bind together like building blocks. Many biologically significant macromolecules are formed by aridity synthesis, a procedure in which monomers bind together by combining their functional groups and generating water molecules as byproducts.

Multiple Option

Which of these elements is non a micronutrient?

1. C
2. Ca
3. Co
4. Cu

Prove Reply

Respond a. C (carbon) is not a micronutrient.

Which of the following is the proper name for molecules whose structures are nonsuperimposable mirror images?

1. structural isomers
2. monomers
3. polymers
4. enantiomers

Show Answer

Answer d. Enantiomers are molecules whose structures are nonsuperimposable mirror images.

Truthful/False

Aldehydes, amides, carboxylic acids, esters, and ketones all contain carbonyl groups.

Ii molecules containing the same types and numbers of atoms but different bonding sequences are called enantiomers.

Think about It

1. Why are carbon, nitrogen, oxygen, and hydrogen the most abundant elements in living matter and, therefore, considered macronutrients?
2. Identify the functional group in each of the depicted structural formulas.
   
3. The structural formula shown corresponds to penicillin G, a narrow-spectrum antibiotic that is given intravenously or intramuscularly as a treatment for several bacterial diseases. The antibody is produced past fungi of the genus Penicillium.
   
   1. Identify three major functional groups in this molecule that each comprise ii simpler functional groups.
   2. Proper noun the two simpler functional groups composing each of the major functional groups identified in (a).

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Source: https://courses.lumenlearning.com/microbiology/chapter/organic-molecules/

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