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Table titled: Common functional groups found in biomolecules; 3 columns, name, functional group and class of compound.  Aldehyde has a red C  double bonded O and an H; the C is also bound to a black R. This is found in carbohydrates. Amine has a red C double bonded to an O and single bonded to an NH. The C and the N are each also bound to a black R. This is found in proteins. Amino has a red NH2 bound to a black R. This is found in amino acids and proteins. Phosphate has a red PO3H2; the P is also bound to a black R. This is found in nucleic acids, phospholipids and ATP. Carbonyl has a red C double bonded to an O; the C is also bound to 2 black Rs. This is found in ketones, aldehydes, carboxylic acids, amides. Carboxylic acid has a red C double bonded to an O and to an OH; the C is also bound to a black R. This is found in amino acids, proteins, and fatty acids. Ester has a red C double bonded to an O and single bonded to another O. The C is bound to a black R and the single bonded O is also bound to a black R. This is found in lipids and nucleic acids. Ether has a red O bound to 2 black Rs. This is found in disaccharides, polysaccharides, and lipids. Hydroxyl has a red OH bound to a black R; this is found in alcohols, monosaccharides, amino acids, and nucleic acids. Ketone has a red C double bonded to an O; the C is also bound to 2 black Rs. This is found in carbohydrates. Methyl has a red CH3 bound to a black R. This is found in methylated compounds such as methyl alcohols and methyl esters. Sulfhydryl has a black R bound to a red SH.. This is found in amino acids and proteins

Macromolecules

Carbon chains form the skeletons of most organic molecules. Functional groups combine with the chain to form biomolecules. Because these biomolecules are typically large, we call them macromolecule s. Many biologically relevant macromolecules are formed by linking together a great number of identical, or very similar, smaller organic molecules. The smaller molecules act as building blocks and are called monomer s , and the macromolecules that result from their linkage are called polymer s . 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 will be discussed in Biochemistry of the Genome .

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

H—monomer—OH + H—monomer—OH H—monomer—monomer—OH + H 2 O

[link] shows dehydration synthesis of glucose binding together to form maltose and a water molecule. [link] summarizes macromolecules and some of their functions.

A diagram showing dehydration synthesis. On the left are two glucose molecules. The OH attached to carbon 1 in the first molecule is red; as is the H attached to the O on carbon 4 in the second molecule. An arrow indicates points to a new molecule that is missing the red OH and H from the previous image. In their place, the O that was attached to the H on carbon 4 is now also attached to carbon 1 of the other molecule.
In this dehydration synthesis reaction, two molecules of glucose are linked together to form maltose. In the process, a water molecule is formed.
Some Functions of Macromolecules
Macromolecule Functions
Carbohydrates Energy storage, receptors, food, structural role in plants, fungal cell walls, exoskeletons of insects
Lipids Energy storage, membrane structure, insulation, hormones, pigments
Nucleic acids Storage and transfer of genetic information
Proteins Enzymes, structure, receptors, transport, structural role in the cytoskeleton of a cell and the extracellular matrix
  • What is the byproduct of a dehydration synthesis reaction?

Key concepts and summary

  • The most abundant elements in cells are hydrogen, carbon, oxygen, nitrogen, phosphorus, and sulfur.
  • Life is carbon based. Each carbon atom can bind to another one producing a carbon skeleton that can be straight, branched, or ring shaped.
  • The same numbers and types of atoms may bond together in different ways to yield different 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 individual units, the monomers , which bind together like building blocks. Many biologically significant macromolecules are formed by dehydration synthesis , a process in which monomers bind together by combining their functional groups and generating water molecules as byproducts.

True/false

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

True

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

False

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Short answer

Why are carbon, nitrogen, oxygen, and hydrogen the most abundant elements in living matter and, therefore, considered macronutrients?

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Identify the functional group in each of the depicted structural formulas.

Figure A has a C bound to an OH. Figure B has a C double bonded to an O as well as a single bonded OH and R. Figure C has an N bound to an R and two Hs.
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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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