An ionic bond is the electrostatic force that holds ions together in an ionic compound. Commonly, ionic bonds are formed in proteins when there is juxtaposition of positive and negative charges that exist in the event there is formation of amino acids holding opposite charges (John 2008, pp.6-7). The significance of ionic bonds in protein is to diffusing the influence of covalent bonds. In amino acids, some contain the -COOH while others the -NH2 and whenever there is interaction between the two types it leads to the transfer of the H+ into the -NH2. This action leads to the formation of an ionic bond that is further facilitated by the closeness of the positive and negative group within the amino chain. The illustration below shows the formation of an ionic bond in an amino chain;
Secondly we look at the use of ionic bonds in nucleic acids. Through the nucleobases of the RNA and DNA, pairing sequences can be witnessed that require weak ionic bonding of the active functional groups. These nucleobases are paired in the adenine-thymine, cytosine-guanine sequence for DNA while in RNA the pairing of adenine-uracil is preferred. The polarity that is contained in the formation of the pairs within the DNA and RNA structures is weak positive and negative which act to stabilize the molecule (John 2008, pp.8-9).
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(John, M. 2008. Fibrous Proteins: Amyloids, Prions and Beta Proteins: Journal on Advances in Protein Chemistry and their uses, Vol. 73 (5). Pp. 6-9.)
ii) Van der Waals Interactions
These are intermolecular forces that act between molecules through dipole-dipole, dipole-induced dipole and dispersion forces. For example, in polymer formation these forces play a significant role due to their weak forces that quickly string the monomers together to form the required polymers (Rao 2008, pp.2).
Carbohydrates have an important use for the van der Waals forces especially when the lower monomers such as glucose and fructose join to form sucrose. On the other hand, the van der Waals interactions are essential in the manner which proteins form bonds within themselves and other molecules through surface interaction (Rao 2008, pp.3-4). The functionality of these forces in protein molecules is in the manner which they oversee the folding in the protein molecules. If the van der Waals forces are repulsive in nature, the uncharged atoms come close. Furthermore, if the van der Waals forces are of the attractive nature the interactions that go into the induced dipoles arise from charge density fluctuations in the uncharged detached atoms (Rao 2008, pp.6).
(Rao, V. 2008. Conformation of Carbohydrates: A Guide for Carbohydrates Behaviour in the Body and General Reactions, Vol.5 (2). Pp. 2-6.)
iii) Hydrophobic Bonds
Hydrophobic bonds are those that are formed in the event that the molecules involved do not form hydrogen bonds due to their quality of being repellent to the atoms that form water. For instance, the hydrophobic bonds in proteins are as a result of having the hydrophobic amino acids interacting with water. The non-polarity of these amino acids leads them to create bonds with the polar solvent which in this case is water. The importance of having the hydrophobic bonds in proteins is to act as restrictions to the number of ways that it can be folded to form other molecular conformations (Dominic 2010, pp.46-47).
(Dominic, W. 2010.
Mechanism and Theory in Food Chemistry: General Principles on World Science, Wiley Publishers. New York. Pp. 46-47.)
iv) Hydrogen Bonds
Hydrogen bonds are of the order that there has to be the drawing of electrons from the two hydrogen atoms that form the water molecule through the effect that is created by the oxygen atom. This effect leads to the creation of partial positive charges on each of the hydrogen atoms leading to a likelihood of hydrogen bond creation. In macromolecules, proteins exhibit a tendency to donate hydrogen bonds. Their role is quite pronounced in the manner which they act as stabilizers in DNA-protein complexes. This means that the polar hydrogen atoms that are formed in the amino groups will tend to form direct specific bonds (George 2005, pp.12).
(George, A. 2005. An Introduction to Hydrogen Bonding and Structure Formation in Macromolecules: A Journal on Physical Chemistry, Vol.6 (2). Pp. 12.)
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2 (a) A Quaternary Structure
A quaternary structure describes a complete biological molecular unit that is formed from two or more chains that are joined together. The difference that this structure has with the tertiary structure is that the chain interactions are less of intra-chain than inter-chain (Peter 2009, pp.89).
b) The Structure of Myoglobin; whether it is Quaternary
The structure of Myoglobin is not quaternary but tertiary in nature. The reason for this is that it is enabled to be consistent with the function that it does in the muscles when it bonds with molecular oxygen. The compound oxymyoglobin that is stored in the muscle tissues acts as the source of oxygen in the tissues when the levels go down (Peter 2009, pp.90).
(Peter, A. 2009. An Introduction to Hydrogen Bonding and Macromolecule Structure Formation: The Royal Science Journal in Physical Chemistry, Vol.10 (9). Pp. 89-90.)
3 Explanation on our Current Understanding of how Eukaryotic Cells are likely to have evolved from Prokaryotic Ancestors
The common notion holds that the most complex of organisms evolved from the simplest of life forms that were single celled at the begining. The similarities between the two cells can be traced to the most basic organelles that first existed in the prokaryotes which lacked the most impotant of them all, the nucleus. In modern science, we understand that the evolution started with the existence of a simple cell which is characteristic of a prokaryotic. In terms of existence, it is believed that the prokaryotic cells came into being about 2 billion earlier creating the platform for the existence for the more complex eukaryotic cell (Charles 2009, pp.45).
The complexity of the two cells can be seen by the manner which the eukaryotic cell has complex and elaborate cell organelles which the prokaryotic cell does not have but has empirically proven to be the source of the complex eukaryotic cell (Charles 2009, pp.46-48).
(Charles, H. 2009. Organization and Control in Prokaryotic and Eukaryotic Cells: A Journal on Twentieth Symposium of the Society for General Microbiology, Vol.15 (3). Pp. 45-48.)
4. The Cell Theory as Developed by Schwann and later Extended by Virchow
Schwann developed the cell theory through a systematic study of the organism's cells. First he made the comparison between the plant and animal cell which he correctly distinguished as different structurally. His milestone contributions came in the form of an accurate trace to the origin of cells and a credible explanation of the most pronounced process of differentiating tissues in higher animals. Through the developments that Schwann had made in studying the cell as the basic unit of life, Virchow continued with the pathological aspects that are present within cells. The conclusions that were drawn by Virchow stated that the cells acted as a source of diseases that weakened normal tissue cell hence causing its spread (Schulz 2007, pp.4-6).
(Schulz, E. 2007. Principles of the Cell Theory, Structure and their Early Existence: Springer Advanced Texts in Chemistry, Vol.4 (2). Pp. 4-6.)
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Proteins are classified among the main four biological macromolecules that are exhibited in every organism. Consequently, they are formed from the consistent polymerization of amino acids with each polypeptide containing residues in the form of L-α-amino arranged in a sequential large number. Through various interaction forms, the peptides can become structurally strong as is evidenced in the formation of silk. In most instances, the silk that is normally obtained for commercial purposes is harvested from the groups of larvae that make the silkworm that is reared for the purposes of production of silk. Structurally, silk has a triangular prism-like structure that gives it its shimmering look as a result of light being dispersed to display various colours (Nicholas 2005, pp.13).
Though most of the silk that is used is assumed to be produced by the silkworm, there are other insects that can produce. For instance several insect larvae such as those for bees, ants and wasps do produce silk but not to the levels of being used for the production of textiles. Other silk producers are in the family of arthropods in the form of wild caterpillars and arachnids through spiders which have been known to produce silk for textile use (John 2010, pp.37).
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Production of Silk from Silkworms
When the reared silk moths lay eggs, they are allowed to hatch on uniquely prepared paper leading to the production of silkworms that are actual caterpillars of the metamorphosing moths. To make them grow quickly and produce quality silk, these caterpillars are fed on mulberry leaves. After growing to 10,000 times their original size which takes approximately 35 days, these caterpillars are considered ready for the process of spinning silk. Upon being placed on straw frames, the silkworms start by producing liquid silk through their spinnerets which is further augmented by the sericin which turns it to solid upon exposure to air (Nicholas 2005, pp.14).
Through the cocoon that is produced, the silkworm is able to produce up to 1 mile of silk filament a process that takes about 3 days. This amount of silk that is produced by one caterpillar is considered ready for harvest which is done by first killing the it only leaving a few to layer eggs for the next generation. To make the harvested silk more legible for textile use, it is placed in hot water to lessen the tensile strength of sericin in the cocoon and then unwound to give a continuous thread (John 2010, pp.38).
The Physical Properties of Silk
When formed from the silkworms, silk tends to have a triangular shape that is 8µm wide that enhances its high quality shiny nature. In its structure there are chains of the fibroin nature that consist of beta sheets through their repeat arrangement of amino acids. When these fibroins are exposed to light, they reflect back through an array of various colours that are dispersed from the natural light. When secreted from the glands in the silkworms, the fibres extend allowing sericin which is a kind of protein to act as glue to have strong strands. This structure is known to have a considerable reduction in its strength when immersed in water leading to strength reduction of up to 20%. Moreover, its structure does not regain its shape once stretched a fact that damages its initial quality (John 2010, pp.38-39).
Chemically, silk constitutes of fibroin and sericin which are protein in nature with fibroin being the main component. To enhance strength; sericin is used by providing the natural glue that joins two strands together. The main amino acids that are present in the fibroin are; Gly-Ser-Gly-Ala-Gly-Ala that causes the formation sheets that are beta pleated. To make the chain that is formed strong enough, hydrogen bonds come in handy forming strong networks from below, above and the side. The presence of Glycine, an amino acid, enhances the strength of the fibres making it more resistance to excessive stretching. When it comes to reacting with mineral acids, silk is quite resistant safe for sulphuric acid which dissolves it to yellow (Nicholas 2005, pp.15).
Silk Uses and Functions
It is a good absorber a fact that makes it preferred for wearing in hot weather and during active exercise. Its low conductivity also enhances its use during the cold season thus making it a preferred textile material for clothing and thus in designing ties, shirts, dresses, lingerie, kimonos and robes. Not to be restricted to the fashion industry, silk finds its use in upholstery and house furnishing due to its attractive nature and drape suitability. It is used in window treatments, wall hangings, bedding, wall covering and on floor rugs to enhance the floor setting. For elaborate commercial and factory uses, silk has been used in the manufacture of balloons, parachutes, artillery gunpowder, bicycle tires, bags and comfort filling making the protein the most preferred material than any other textile (Nicholas 2005, pp.16-18).
Industrially, silk usage can not be overruled though it has to undergo treatment to extract the sericin that naturally coats the natural silk during production. After this has been done, it can be used in the preparation of surgical sutures that are non-absorbable. This technology has been widely employed in the manufacture of undergarments that are less irritating to children and adults suffering from eczema (Nicholas 2005, pp.20).
In conclusion, it can be said that the process of silk production has been found to be quite repugnant when it comes to animal rights. Through the process of harvesting, it is common to have the silkworms killed in order to have the cocoon for processing. With the advent of the 20th century, artificial silk should be used so that less cruelty is evidenced whenever silk is cultivated. Moreover, other materials should be advocated for use in the textile industry with special reference to cotton which does not require the killing of the cotton plant. As a strong fibre protein, silk should be moderately use avoid overexploitation of the silkworm (John 2010, pp.40).
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