What Is Organic Chemistry?
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Organic molecules are the chemicals of life, compounds composed of more than one type of element, that are found in, and produced by, living organisms. The feature that distinguishes an organic from inorganic molecule is that organic molecules contain carbon-hydrogen bonds, whereas inorganic molecules do not. The four major classes of organic molecules include carbohydrates, proteins, lipids and
Article Summary: What substances are within the realm of organic chemistry? This article covers the main categories of naturally occurring organic macromolecules: carbohydrates, proteins, nucleic acids and lipids.
Organic Molecules: Carbs, Proteins, Lipids & Nucleic Acids
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Also known as polypeptides, these large organic molecules have many roles within living cells. They are part of cell membranes, act as enzymes in cellular reactions, and are vital molecules of our immune system, protecting us from invading microbes. Proteins are composed of monomers called amino acids joined together with peptide bonds.
Lactose, a di-saccharide made of glucose and galactose.
These peptide chemical bonds link amino acids together into chains, like the beads on a long necklace. A dipeptide has two amino acids linked together, a polypeptide, more than two. Although there are hundreds of different amino acids, most organisms use only 21 to build proteins.
Primary structure of a protine, amino acids linked together, like beads on a string.
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The term carbohydrate is actually a descriptor of what these molecules are composed of; carbon hydrates, in a ratio of one carbon molecule to one water molecule (CH2O)n. The word saccharide is a handy synonym for carbohydrate, because it can be preceded with a prefix indicating the size of the molecule (mono-, di-, tri- poly-):
- Monosaccharides: The simplest, single sugars. Examples: Glucose and fructose are monosaccharides.
- Disaccharides: Double sugars that are a combination of two monosaccharides. Example: Sucrose (table sugar) is made of glucose and fructose together.
- Polysaccharides: These are polymers composed of several sugars. They can be one type of monomer (many of same monosaccharide) or mixture of monomers. Example: Starch is a polysaccharide composed of many glucose molecules.
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