The Concept of Chemical Bonding

THE CONCEPT OF CHEMICAL BONDING OF MOLECULES IN CELL BIOLOGY Cell life is very dependent on thousands of chemical bonds that interact with each other and react very beautifully and regularly in coordination between one molecule and another so that at one time and place it will influence the cell's genetic instructions and also its environment. How can cells take in their food and obtain information from their environment? How do cells convert energy from food for work (moving, synthesizing to produce essential components, reproduction)? How do cells connect and interact with cells in a tissue? How do these cells communicate with each other so that the organism can carry out all its functions? So all these questions are goals that can be answered by studying Cell Biology. All chemical bonds that occur between molecules to support cell life which ultimately will support the life of organisms occur in the water environment. This is an important basis, where water is a molecule that is very abundant in biological systems. Many biomolecules (such as sugar) are present in water, with intermolecular bonds described as hydrophilic (water-loving), and there are other biomolecules (such as triaglycerol fats) that are hydrophobic (water-avoiding). Meanwhile, other biomolecules can have both properties because of the unique intermolecular bonds so that they have amphipathic properties (having regions with hydrophilic and hydrophobic properties) such as those found in phospholipids. All the molecules with these unique properties will build the cell membrane and all the organelles in the cell. Molecules are a combination of atoms through chemical bonds so that they reflect the properties of the molecule in question. The properties of chemical elements and the properties of compounds formed to support life result from their atomic structure. Atoms have neutrons, protons and electrons which can later be used as a reference in determining the atomic weight which is expressed as daltons. The presence of electrons in an atom will affect the amount of energy produced by an atom, so that when atoms interact to form molecules, the properties of the atoms will be reflected in the molecules produced through covalent and ionic chemical bonds. A covalent bond is the sharing of a pair of valence electrons by two atoms. The existence of covalent bonds makes atoms such as amino acids linked together, while non-covalent bonds help connect proteins to bond between proteins so that together they become complementary structures that have special functions. Thus, small molecules will become the basic structure for constructing large molecules. An example is that in general information will be carried by the DNA macromolecule, which is composed of four small molecules linked together, namely adenine (A), thymine (T), guanine (G), and cytosine (C). The ability of an atom to attract electrons from a covalent bond is called the atom's electronegativity. The more electronegativity an atom has, the stronger the atom will pull shared electrons towards itself. These bonds are called nonpolar covalent bonds, such as the bonds that occur between hydrogen (H2) and oxygen (O2) to form water molecules. On the other hand, if an atom is more electronegative than another atom, then an electron will not be shared equally which is called a polar covalent bond, for example the bond in the water molecule. Hydrogen, oxygen, carbon, nitrogen, phosphorus and sulfur are elements that are often found in biomolecules. Each atom has a character and will bond covalently with other atoms so that it has a different shape and size where these atoms can have their own electrons or share electrons. Bonds that occur between molecules often cause a more electronegative atom to seize an electron pair from the molecule next to it or bonded to it. An atom or molecule that has a positive charge is called a cation and vice versa if it has a negative charge it is called an anion. Because of these opposite charges, there will be an attraction between atoms which is called a covalent bond, where environmental conditions will greatly influence the strength of the ionic bond.