Atomic structure, chemical bonding, and living organisms

Chemistry of Living Things

Basic chemistry dictates that matter refers to anything which occupies space and has mass. Elements are the smallest form of matter which cannot be broken down further to a simpler form. Examples are aluminum and iron. An atom is the smallest functional unit of matter that can take part in a chemical reaction and they are what make up elements. The atom has the particles that are positively charged known as protons, an equal number of neutral particles known as neutrons. Protons and neutrons are found in the nucleus. There are also the particles that are negatively charged called electrons that orbit around the nucleus. In most cases, the number of protons is equal to the number of electrons making the atom neutral. Protons and neutrons account of the mass of the atom. Atoms also have an atomic mass, also known as mass number, which is the number of protons and neutrons in the nucleus. They also have an atomic number which is the number of protons in the nucleus Johnson 26(; Hunter 104)

There are also isotopes which are atoms with more or fewer neutrons that what the usual case for the element itself is. For example, carbon has 6 protons and 6 neutrons making it have an atomic mass of 12 but carbon-14 isotope is known so since it has 2 extra neutrons. These isotopes are usually unstable and tend to give-off energy in the form of radiation till they reach a state which is more stable. Radiation emitted by radioisotopes can be dangerous to living things because it can damage tissues. However, certain radioisotopes have important medical and scientific uses. For example, radioisotopes which give off energy for long are used in medicine as pacemakers to act as a means of power supply Johnson 27-28()

Types of chemical bonds

Atoms combine to lead to the formation of molecules. Molecules are stable associations between two or more atoms. Good examples are water (H2O) and sodium chloride (table salt -- NaCl).Chemical bonding is what allows atoms to form molecules. There are three major types of chemical bonds that form between chemicals Johnson 28()

First is the covalent bond. This is a strong bond in which the atoms share the number of electrons in each atom resulting in the outermost shell of electrons being maximally filled. A good example of this bond is the hydrogen and oxygen bond in a water molecule Johnson 31()

Second is the ionic bond which is a bond of moderate strength which is between two ions which have an opposite charge that were formed as a result of the irreversible transfer of one or more electrons. A good example is the bond that exists between the sodium ion and chloride ion in salt Johnson 31()

The last type of bond is the hydrogen bond which is relatively weak and is formed between regions of molecules with opposite charges which have hydrogen atoms that are covalently bonded. A good example is the bond which exists between the molecules of water Johnson 31()

Life depends on water

Life depends largely on water. In fact, water is the content which accounts for about 60% of the body weight. Water serves several purposes in the body. One is that it regulates the temperature of the body. It prevents large increases in the temperature of the body when excess heat is produced through its release by sweating. As the water evaporates from the skin surface, it cools the body Johnson 32()

Hydrogen ions which usually come from water help to maintain the pH level of the body at 7 which is neutral. Blood has a slightly more alkaline pH at 7.4 meaning that the concentration of hydrogen ions in blood is lower as compared to that in plasma. This helps to maintain homeostasis because changes in pH of the body can affect interactions between hormones, destroy tissues or affect chemical reactions that take place in the body Johnson 33-34()

Importance of carbon in life

Carbon is the common building block that is found in all organic molecules. This is as a result of the strong covalent bonds that it forms. It can make up to four covalent bonds with other molecules thus making it have an ideal structure to branch into several directions Johnson 36()

Carbon is contained in carbohydrates. They are compounds that have carbon, hydrogen and oxygen. There are 3 forms of carbohydrates. First are the monosaccharides which are simple sugars. They have simple structures in the ration of 1:2:1. They usually contain 5-6 atoms of carbon arranged in a 5-6 member ring. Oligosaccharides are monosaccharides which are combined in short strings that are linked together through dehydration synthesis. Sucrose is one of the oligosaccharides. It is a disaccharide since it consists of simply two monosaccharides. The last form are the polysaccharides which are straight or branched chains of monosaccharides joined together. Polysaccharides store energy. In animals, the storage polysaccharide is glycogen while in plants, it is starch Johnson 37-38()

Lipids

Lipids are insoluble organic molecules. There are three subclasses. First are the triglycerides which are neutral fats synthesized from one glycerol molecule and three fatty acids. Fatty acids on the other hand are chains of hydrocarbons with about 16-18 carbons which end in a carboxyl group (COOH). Triglycerides are stored in adipose or fat tissue and in the body, they are an important source of energy for storage. The second group is the phospholipids which are the primary component in the structure of cell membranes. Phospholipids have one molecule of glycerol but only two fatty acids. Steroids are the last group. They are composed of four rings and a backbone of 3 six-membered rings of carbon and 1 five-membered carbon ring. A good example of steroids is cholesterol Johnson 39-40()

Nucleic acids

Nucleic acids are stores of genetic information. They are two, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA is the genetic material in all living things and it directs what the cell does. It also contains the instructions for the production of RNA. RNA on the other hand, contains the instructions for production of proteins. RNA also serves as the genetic material in some viruses Johnson 44()

Both DNA and RNA are composed of nucleotides which have a 5-carbon sugar, a double or single ringed structure with nitrogen and lastly, a phosphate groups. There are only four DNA and four RNA nucleotides that are present Johnson 44()

The structure of RNA is similar to that of DNA. However, there are some few exceptions. First is that the sugar in the nucleotides is ribose and not deoxyribose. Secondly, RNA is single-stranded and is shorter than DNA. RNA has only one of its four nitrogen-containing base molecules being different Johnson 45()

ATP

Adenosine triphosphate is the source of energy. It consists of a base of adenine, 4-carbon sugar ribose and 3 phosphate groups. When ATP is broken down, it produces adenosine diphosphate (ADP), an inorganic phosphate and releasing energy in the process. ATP is then replenished by energy that is in the food that is eaten or can also come from glycogen or fats stored in the body Johnson 46()