What is the difference between functional group and macromolecule

These traits in combination permit the formation of a vast number of diverse molecular species necessary to form the structures and enable the functions of living organisms. Living organisms contain inorganic compounds mainly water and salts; see Fundamentals of Physics and Chemistry Important to Microbiology and organic molecules.

Organic molecules contain carbon; inorganic compounds do not. Carbon oxides and carbonates are exceptions; they contain carbon but are considered inorganic because they do not contain hydrogen. The atoms of an organic molecule are typically organized around chains of carbon atoms.

They are small, simple compounds that play important roles in the cell, although they do not form cell structures. Most of the carbon found in organic molecules originates from inorganic carbon sources such as carbon dioxide captured via carbon fixation by microorganisms.

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 block of life. Carbon is a very unique element in that it has four valence electrons in its outer orbitals and can form four single covalent bonds with up to four other atoms at the same time see 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 methane, in which carbon binds only to hydrogen Figure 2.

The carbon skeleton of organic molecules can be straight, branched, or ring 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 variety of compounds. No other element has the ability to form so many different molecules of so many different sizes and shapes. Molecules with the same atomic makeup but different structural arrangement of atoms are called isomers.

The concept of isomerism is very important in chemistry because the structure of a molecule is always directly related to its function. Slight changes in the structural arrangements of atoms in a molecule may lead to very different properties. Chemists represent molecules by their structural formula , which is a graphic representation of the molecular structure, showing how the atoms are arranged.

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 have the same molecular formula, C 6 H 12 O 6 , but we can see from Figure 3 that the atoms are bonded together differently. Isomers that differ in the spatial arrangements of atoms are called stereoisomers ; one unique type is enantiomers. The properties of enantiomers were originally discovered by Louis Pasteur in 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, as illustrated by the examples of structural differences in the enantiomeric forms of the monosaccharide glucose or the amino acid alanine Figure 4. Many organisms are only able to use one enantiomeric form of certain types of molecules as nutrients and as building blocks to make structures within a cell.

Some enantiomeric forms of amino acids have distinctly different tastes and smells when consumed as food. For example, L-aspartame, commonly called aspartame, tastes sweet, whereas D-aspartame is tasteless. Drug enantiomers can have very different pharmacologic affects. For example, the compound methorphan exists as two enantiomers, one of which acts as an antitussive dextro methorphan, a cough suppressant , whereas the other acts as an analgesic levo methorphan, a drug similar in effect to codeine.

Enantiomers are also called optical isomers because 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.

The d and l labels are derived from the Latin words dexter on the right and laevus on the left , respectively. These two different optical isomers often have very different biological properties and activities. Functional groups are groups of atoms that occur within molecules and confer specific chemical properties to those molecules.

Molecules with other elements in their carbon backbone are substituted hydrocarbons. Each of the four types of macromolecules—proteins, lipids, carbohydrates, and nucleic acids—has its own characteristic set of functional groups that contributes greatly to its differing chemical properties and its function in living organisms. A functional group can participate in specific chemical reactions.

Some of the important functional groups in biological molecules are shown in Figure ; they include: hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl. These groups play an important role in the formation of molecules like DNA, proteins, carbohydrates, and lipids. Most macromolecules are made from single subunits, or building blocks, called monomers.

The monomers combine with each other via covalent bonds to form larger molecules known as polymers. In doing so, monomers release water molecules as byproducts. In a dehydration synthesis reaction between two un-ionized monomers, such as monosaccharide sugars, the hydrogen of one monomer combines with the hydroxyl group of another monomer, releasing a molecule of water in the process. The removal of a hydrogen from one monomer and the removal of a hydroxyl group from the other monomer allows the monomers to share electrons and form a covalent bond.

Thus, the monomers that are joined together are being dehydrated to allow for synthesis of a larger molecule. A dehydration synthesis reaction involving un-ionized moners.. In the process, a water molecule is formed. When the monomers are ionized, such as is the case with amino acids in an aqueous environment like cytoplasm, two hydrogens from the positively-charged end of one monomer are combined with an oxygen from the negatively-charged end of another monomer, again forming water, which is released as a side-product, and again joining the two monomers with a covalent bond.

A dehydration synthesis reaction involving ionized monomers. In the process a water molecule is formed. As additional monomers join via multiple dehydration synthesis reactions, the chain of repeating monomers begins to form a polymer. Different types of monomers can combine in many configurations, giving rise to a diverse group of macromolecules. Three of the four major classes of biological macromolecules complex carbohydrates, nucleic acids, and proteins , are composed of monomers that join together via dehydration synthesis reactions.

Complex carbohydrates are formed from monosaccharides, nucleic acids are formed from mononucleotides, and proteins are formed from amino acids. There is great diversity in the manner by which monomers can combine to form polymers. For example, glucose monomers are the constituents of starch, glycogen, and cellulose. These three are polysaccharides, classified as carbohydrates, that have formed as a result of multiple dehydration synthesis reactions between glucose monomers.

However, the manner by which glucose monomers join together, specifically locations of the covalent bonds between connected monomers and the orientation stereochemistry of the covalent bonds, results in these three different polysaccharides with varying properties and functions.

In nucleic acids and proteins, the location and stereochemistry of the covalent linkages connecting the monomers do not vary from molecule to molecule, but instead the multiple kinds of monomers five different monomers in nucleic acids, A, G, C, T, and U mononucleotides; 21 different amino acids monomers in proteins are combined in a huge variety of sequences.

Each protein or nucleic acid with a different sequence is a different molecule with different properties. Privacy Policy. Skip to main content. The Chemical Building Blocks of Life. Search for:. Organic Compounds. Organic Molecules and Functional Groups Functional groups are groups of molecules attached to organic molecules and give them specific identities or functions.

Learning Objectives Describe the importance of functional groups to organic molecules.