are assemblage of large molecules such as proteins, nucleic acids and polysaccharides and as these molecules are larger by many exponential powers than the smaller units or molecules from which these are made. These smaller units numbering thousands are called monomers. These monomers can be linked together to produce macromolecules which are also termed as polymers. The molecules are possible due to the presence of carbon and its tetra valence which enables these molecules to build chains of molecules giving rise to various forms of monomers such as amino acids, nucleotides and sugar monomers.
The protein and nucleic acids play a key role in life process and in all kinds of living cells we get to see the amino acids or monomers which combine by polymerisation and form proteins. The polymerisation of amino acids under controlled conditions resembling early Earth like characteristic helped produce protein like polymers.
Similar development were tried for abiotic polymerisation of nucleotides and sugars which tends to happen less readily than normal procedure applied for monomers of proteins
or amino acids. This led to the development of various other useful biomolecules. Proteins due to their high polar and reactive macromolecular structure have helped creating highly acclaimed polymeric materials from the monomers of proteins which helped in making specific gradients of biopolymer and also in the field of bioengineering.
In globular proteins about one third of the residues are involved in tight turns that reverse the direction of polypeptide chains at the surface of the molecules and thus make possible the overall globular structure. These reverse turns or loops may be regarded as a third type of ordered secondary structure. The reverse turns are usually classified according to the number of residues they contain and the types of secondary structures that they connect.
The best characterised are the β (beta)
hairpins that link adjacent strands in an anti-parallel β sheet. If only one residue in a chain is not involved in the hydrogen bonding pattern of the sheet, it is found to have a tight ϒ turn. The β turns in which the two residues are not involved in hydrogen bonding of the β sheet are much more common, the two residues on either side of the non-hydrogen bonded residues also participate in the definition of β turn.Proteins
are composed of carbon, hydrogen, oxygen and nitrogen covalently bonded and in some proteins the presence of sulphur is also observed. The basic building blocks are the 20 amino acids which vary in length of their carbon chain backbones and atoms connected to that backbone. Each amino acid has a carboxyl group (-COOH), amine (-NH2), a hydrogen and the R group. The covalent bonds form between different amino acids to form proteins and are referred as peptide bonds.
Proteins function in a number of very important manner in our body and many of these are structural proteins. The primary structure of proteins is determined by the amino acids sequence while the secondary structure is determined by the hydrogen bonds between the amino acids that helps the protein to coil into helices or pleated sheets. The secondary structure of protein is alpha helix structure in which a single protein chain adopts a shape that resembles a coiled spring or helix with the coil configuration maintained by hydrogen bonds.
The hydrogen bonds are between >N – H and >C = O groups
. The twist of the helix forms a right handed spiral. The hydrogen bonds between C=O and N-H entities are oriented parallel the helical axis. The hydrogen bond involves a C=O group of one amino acid and an N-H group of another amino acid. If these hydrogen bonds are destroyed the protein becomes non-functional. These hydrogen bonds are broken only at a very high temperature or by increasing the acidic property or surrounding.
The tertiary form of protein is basically a secondary folding caused by peptide bond interaction with sulphur atoms of various amino acids which affect the structure as well as function of the protein. The quaternary protein structure is determined by spatial relationship between individual units.
What are the Building Blocks Monomers of Proteins?
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All the proteins are polymers of amino acids or in other words amino acids are the building blocks or monomers from which all proteins or polymers are made. Most of proteins are made up of entirely or only 20 amino acids.
Although there are a few other amino acids in some proteins we need to differentiate as per the variation in molecular size of different proteins. Since these building blocks of amino acids are of 20 different kinds, 10 very essential and 10 not so essential, so all the permutation and combinations of arranging close to 90,000.00 proteins makes a huge effort. The complexity and specificity of proteins.
The building blocks of nucleic acid chains are nucleotides. These nucleotides are composed of three simpler units, a base, a monosaccharide and a phosphate.DNA and RNA
are polymers and as proteins consist of chains of amino acids and polysaccharides these also consist chains of nucleic acids. The bases that are found in DNA and RNA are categorically heterocyclic aromatic amines in nature. Two are adenine (A) and guanine (G) known as purines while the other three cytosine (C), Thymine (T) and uracil (U) are pyrimidines.
Out of these two of purines and one of pyrimidines are found in both DNA and RNA but uracil is observed only in RNA.
Both DNA and RNA contain four bases, two of purines and pyrimidines.
The deoxyribonucleic acid or DNA and ribonucleic store and transmit genetic informations, the DNA has four nitrogenous bases, adenine, cytosine, guanine and thymine and hence the codings in DNA is written in a four letter alphabet.
The list of proteins consist of both very essential and not so essential list where it is further classified into water hating or hydrophobic and water loving or hydrophilic along with the proteins which is neither water hating or water loving in nature.
|| In between the two forms
| Valine (Val)
|| Asparganine (Asn)
|| Glycine (Gly)
| Leucine (Leu)
|| Glutamic acid (Glu)
|| Alanine (Ala)
| Isoleucine (Ile)
|| Glutamine (Gln)
|| Serine (Ser)
| Methionine (Met)
|| Histidine (His)
|| Threonine (Thr)
| Phenylalanine ((Phe)
|| Lysine (Lys)
|| Tyrosine (Tyr)
| Cysteine (Cys)
|| Arginine (Arg)
|| Tryptophan (Trp)
|| Aspartic acid (Asp)
|| Proline (Pro)