Testing for Biomolecules

Topics: Protein, Metabolism, Amino acid Pages: 9 (1447 words) Published: September 14, 2004

The objective is to identify specific chemical substances within a cell and to be able to verify the presence or absence of each one in a cell or food substance for future testing.


The identification of each biomolecular chemical substance should be verified successfully, as well as determining if it is present or absent in the cell(s).

Theoretical Base:

A biomolecule is a substance that naturally occurs in living organisms. Biomolecules consist primarily of carbon and hydrogen, along with nitrogen, oxygen, phosphorus and sulfur. Other elements sometimes are incorporated but these are much less common.

Biomolecules are necessary for the existence of all known forms of life. For example, humans possess skin and hair. The main component of hair is keratin, an agglomeration of proteins which are themselves polymers built from amino acids. Amino acids are some of the most important building blocks used in nature, to construct larger molecules.

Another type of building block is the nucleotides, each of which consists of three components: either a purine or pyrimidine base, a pentose sugar and a phosphate group. These nucleotides, mainly, form the nucleic acids.

Besides the polymeric biomolecules, numerous small organic molecules are absorbed or synthesised by living systems. Many biomolecules may be useful or important drugs.

Types of biomolecule

A diverse range of biomolecules exist, including:

Small Molecules:

Lipids, Phospholipids, Glycolipids, Sterols


Hormones, Neurotransmitters

Carbohydrates, Sugars



Amino acids





Peptide, Oligopeptide, Polypeptide, Protein

Nucleic acid, i.e. DNA, RNA

Oligosaccharide, Polysaccharide



Nucleosides & Nucleotides

Nucleosides are molecules formed by attaching a nitrogenous base to a ribose ring. Examples of these include cytidine, uridine, adenosine, guanosine, thymidine and inosine.

Nucleosides can be phosphorylated by specific kinases in the cell, producing nucleotides, which are the molecular building blocks of DNA and RNA.


Monosaccharides are carbohydrates in the form of simple sugars.

Disaccharides are formed from two monosaccharides joined together. Monosaccharides and disaccharides are sweet, water soluble, and crystalline. Examples of monosaccharides include the hexoses (glucose, fructose, and galactose) and pentoses (ribose, deoxyribose). Examples of disaccharides include sucrose, maltose, and lactose.

Polysaccharides are polymerized monosaccharides, complex unsweet carbohydrates. They are, generally, large and often have a complex, branched, connectivity. They are insoluble in water and do not form crystals. Examples include starch, cellulose, and glycogen. Shorter polysaccharides, with 2-15 monomers, are sometimes known as oligosaccharides.


Lipids are chiefly fatty acid esters, and are the basic building blocks of biological membranes. Another biological role is energy storage (e.g., triglycerides). Most lipids consist of a polar or hydrophilic head and one to three nonpolar or hydrophobic fatty acid tails, and therefore they are amphiphilic. Fatty acids consist of unbranched chains of carbon atoms that are connected by single bonds alone (saturated fatty acids) or by both single and double bonds (unsaturated fatty acids). The chains are usually 14-24 carbon groups long.

For lipids present in biological membranes, the hydrophilic head is from one of three classes:

Glycolipids, whose heads contain an oligosaccharide with 1-15 saccharide residues.

Phospholipids, whose heads contain a positively charged group that is linked to the tail by a negatively charged phosphate group.

Sterols, whose heads contain a planar steroid ring, for example, cholesterol.


Hormones are produced in the endocrine glands, where they are excreted...

Bibliography: (Theoretical Base and further knowledge):
- Encyclopaedia Britannica 2003
- http://www.fact-index.com/b/bi/biomolecule.html
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