In every chemistry based article, we keep referring to molecules and even among molecules; we specify organic and inorganic molecules.

What are organic molecules?

Organic molecules are nothing but the chemicals of life, compounds that are composed of more than one type of element. Organic molecules are found in, and are produced by living organisms. The feature that distinguishes an organic molecule from inorganic molecule is that the organic molecules contain carbon-hydrogen bonds whereas the inorganic molecules do not. The four major classes of organic molecules include carbohydrates, proteins, lipids and nucleic acids.

Carbohydrates

The term carbohydrates actually describe what these molecules are made of. These molecules contain carbon hydrates in a ratio of one carbon molecule to one water molecule (CH2O).

There are different types of carbohydrates as well. This include saccharide, monosaccharides and polysaccharides.

The word saccharide is another word for carbohydrate, because it can be preceded with a prefix that indicates the size of the molecule (mono-, di-, tri- poly-).

Monosaccharides are the simplest form of molecules as they contain single sugars and have just one molecule. Disaccharides are double sugars and are a combination of two monosaccharides. Polysaccharides are polymers and are composed of several sugars. They can be same monomer (many of same monosaccharide) or mixture of monomers.

Proteins

Proteins are polymers that are composed of monomers called as amino acids. Each amino acid contains contain a...

• base amino group ( -NH2)
• acidic carboxyl group ( -COOH)
• hydrogen atom

All of the above are attached to same carbon atom (the α-carbon or alpha carbon). A fourth bond attaches an alpha carbon to a side group that varies among different amino acids. These side groups are important, as they affect the way the protein's amino acids interact with one another, and how a protein interacts with other molecules. Alhough there are hundreds of different amino acids, most organisms use only 21 to build proteins.

Peptide bonds are the covalent bonds which link amino acids into chains and they together look like the beads on a necklace. A dipeptide is two amino acids that are linked together and a polypeptide is the one that is more than two.

Lipids

Lipids are molecules that are hydrophobic and are not attracted to water because the non-polar covalent bonds that link carbon and hydrogen are not attracted to the polar bonds of water. The four major groups of lipids include fats, phospholipids, waxes and steroids.

Fats

Fats and oils are made from two kinds of molecules; glycerol which is a type of alcohol and three fatty acids which are also known as triglycerides.

Phospholipids

The structure of this type of lipid includes a hydrophobic or a "water hating," hydrocarbon tails and hydrophilic or a water loving phosphate groups on the end. This means that phospholipids are soluble in both water and oil.

Our body cell membranes are made mostly of phospholipids that are arranged in a double layer with the tails from both layers facing inward and the heads facing outward. This is called as lipid bilayer.

Waxes

Waxes are esters of alcohol which are insoluble in water and are difficult to break down. Wax forms protective and waterproof layers on some plants, bacteria, animal fur and integuments of insects.

Steroids

Steroids form the central core of a cholesterol molecule which consists of four fused rings and is shared by all steroids. Cholesterol is a precursor to our sex hormones and Vitamin D. Our cell membranes contain a lot of cholesterol which helps in keeping the membrane flexible and fluid even when our cells are exposed to cooler temperatures.

Nucleic Acids and Nucleotides

Nucleic acids are polymers that are made up of nucleotide monomers. Each monomer of nucleic acid is a nucleotide and consists of three portions; pentose sugar, one or more phosphate groups and one of five cyclic nitrogenous bases.

Nucleotides are linked by covalent bonds between phosphate of one nucleotide and sugar of next, thereby forming a phosphate-sugar backbone. The nitrogenous bases extend from it like teeth of a comb.

Hydrogen bonds form between specific bases of two nucleic acid chains, forming a stable, double-stranded DNA molecule. Hydrogen bonding twists the phosphate-deoxyribose backbones into a helix giving it a typical DNA double helix.

Adenosine 5'-triphosphate or ATP, also known as the energy transfer molecule is a multifunctional nucleotide and is important for the "molecular currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism.

So, now you know all your organic molecules and hope this helps you in understanding chemistry better.