Biomolecules Chemical Analysis

What are Biomolecules?

In our biosphere, there is a wide diversity in living organisms. All living organisms are made up of the same chemicals i.e., elements and compounds. If we analyze a plant tissue, animal tissue, or a microbial paste we obtain elements like carbon. hydrogen. oxygen etc. A similar analysis on a non-living matter says a piece of rock gives a list of similar chemicals But when examined closely it is observed that in living organisms the relative abundance of carbon and hydrogen concerning other elements is higher than on earth crust, these are Biomolecules.

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How to Analyse Chemical Composition of Cells?

By performing chemical analysis, the various biomolecules that are found in living tissues (a vegetable or a piece of liver, etc. ) can be studied. When the living tissue grinds in trichloroacetic acid (Cl₃CCOOH), a thick slurry is formed. This slurry when strained through cheesecloth or cotton gives two fractions, one is the filtrate, which is called acid-soluble pool where thousands of organic compounds are found? The other fraction is called the retentate or the acid-insoluble pool where compounds like proteins, nucleic acids, polysaccharides, etc. are found.


In higher classes, we will learn about how to analyze a living tissue sample and identify a particular organic compound. In brief, it can be said that one extracts the compounds, then subjects the extracts, to various separation techniques till one has separated a compound from all other compounds. Thus, one isolates and purifies a compound.


When the analytical technique is applied to the compound gives us an idea of the molecular formula and the probable structure of the compound. 


Table:- A Comparison of Elements Present in Non - Living and Living Matter

Elements

% Weight of Earth’s Crust

% Weight of Human Body

Hydrogen(H)

0.14

0.5

Carbon(C)

0.03

18.5

Oxygen(O)

46.6

65.0

Nitrogen(N)

Very little

3.3

Sulphur(S)

0.03

0.3

Sodium(Na)

2.8

0.2

Calcium(Ca)

3.6

1.5

Magnesium(Mg)

2.1

0.1

Silicon(Si)

27.7

Negligible


Classification of Biomolecules

Biomolecules are classified into four major types:

  1. Carbohydrates

  2. Proteins

  3. Nucleic Acids

  4. Lipids


Carbohydrates

Carbohydrates are mainly compounds of carbon, hydrogen, and oxygen. These are also known as saccharides because their basic components are sugars. They are of two types, small and large (complex). Small carbohydrates (biomacromolecules) are further divided into monosaccharides, derived monosaccharides, and oligosaccharides. Large carbohydrates (biomacromolecules) are called polysaccharides.


Proteins

Proteins are large-sized macromolecules having one or more polypeptides (chains or polymers of amino acids LInked by a peptide bond). The term polypeptide Is often used Interchangeably with protein. However, a single polypeptide must be at least 50 amIno acId long to qualify for the term. 

As there are 20 types of amino acids. a protein Is said to be a heteropolymer and not considered as a homopolymer. A homopolymer has only one kind of monomer repeating to several numbers of times. CoIIagen Is the most abundant protein In the world. It is the main component of the connective tissue of animals. Ribulose bisphosphate carboxylase-oxygenase (RuBisCo) Is the most abundant proteIn In the whole of the biosphere. RuBIsCo is an enzyme Involved In carbon fIxatIon (photosynthesis). a process by men atmospheric CO₂ Is converted by plants to energy rIch molecules i.e., glucose.


Nucleic Acids

Nucleic acids are polymers of nucleotides and are macromolecules. There are two types of nucleic acids namely- deoxyribonucleic acid (DNA) or ribonucleic acids (RNA). Nucleotides serve as the building block of nucleic acid. A nucleotide is composed of :

  1. Phosphate group.

  2. A five-carbon sugar or pentose sugar.

  3. A heterocyclic nitrogen-containing compound called the base.


Lipids

Lipids are all made of carbon, hydrogen, and little oxygen and are water-insoluble but get dissolved in organic solvents like ether, benzene, acetone, etc. The lipids are not polymers but they are assembled from smaller molecules by dehydration. Lipids could be simply fatty acids or glycerol (which is trihydroxy propane). Many lipids have both glycerol and fatty acids. Some lipids have phosphorus and phosphorylated organic compounds in them. Some lipids have more complex structures.


Fun Facts

Mitochondria are rich in manganese. Molybdenum is necessary for the fixation of nitrogen catalyzed by enzyme nitrogenase. Copper occurs In cytochrome oxidase. Magnesium is essential for a large number of enzymes, particularly those utilizing ATP. Ca and Mg decreases the excitability of nerves and muscles):

  1. Sodium and potassium are responsible for the maintenance of extracellular and intracellular fluids through the osmotic effects of the concentration in none of these two ions. These two ions are also responsible for the maintenance of membrane potential. Na⁺ and K⁺ Ions are also responsible for the transmission of electrical impulses in the nerve cells. However, calcium and magnesium reduce the excitability of nerves and muscles. In cells and extracellular fluid: dibasic phosphate (HPO₄²⁻) and monobasic phosphate (H₂PO⁴⁻) act as acid-base buffers to maintain the H+ Ion concentration of cellular fluids.

  2. The most abundant element in the cell or living matter is oxygen.

  3. Fe⁺⁺ and Cu⁺⁺ are found in cytochromes.

  4. The concentration of the cations inside the cell is K > Na > Ca.

FAQ (Frequently Asked Questions)

1. What are the Primary Metabolites?

Ans. Biomolecules that are required to carry out primary metabolic processes like photosynthesis, respiration, and lipid metabolism, etc. are known as primary metabolites. Primary metabolites have functions that can be seen and play roles that are known in normal physiological processes.

2. What is the Significance of Peptidoglycan?

Ans. Peptidoglycan is present in the bacterial cell wall which is degraded by the enzyme lysozyme, which hydrolyzes the glycosidic bond, killing bacterial cells. Lysozyme is present in tears, presumably a defense against bacterial infections of the eye. It is also produced by certain bacterial viruses to ensure their release from the host bacteria, an essential step of the viral infection cycle.

3. What are Lanolin and Streptokinase?

Ans. Lanolin is an ester of palmitic acid or oleic acid or stearic acid with cholesterol secreted by the cutaneous gland. Cutaneous glands in animals are known to secrete wax lanolin for forming a protective water-insoluble coating on animal fur.


Streptokinase is produced by the bacterium streptococcus is used as a clot buster for removing clots from the blood vessels. Other applications are proteins like casein are used in beauty creams and shampoos.