Chemical Composition of the Animal Body.

                                  Chemical Composition of the Animal Body.

Chemical Composition of the Animal Body.

Animals, like all life forms, are composed of and dependent upon an assortment of chemical compounds. To understand the chemistry of life, we need to first understand the basics of general chemistry. The elements that naturally occur in animals include (in order of descending percent body weight, approx):

• oxygen (65%)
• carbon (19%)
• hydrogen (10%)
• nitrogen (3%)
• calcium (1%)
• phosporus (1%)
• potassium (0.2%)
• sulfur (0.1%)
• sodium (0.1%)
• chlorine (0.1%)
• magnesium (0.1%)
• manganese (0.1%)
• iron (0.1%)
• copper (0.1%)
• iodine (0.1%)

Molecules can be subdivided into two main groups, those that contain carbon, organic molecules and those that lack carbon, inorganic molecules. The chemistry of the organic molecules is influenced primarily by the characteristics of carbon. Carbon atoms bond together with other carbon atoms to form chains and rings of a wide range of lengths and configurations. Some examples of organic molecules include:

• carbohydrates - animals' main source of energy
• lipids - building blocks of fats, make up cell parts and supply energy
• proteins - structural material, hormones, enzymes, metabolic functions, endocrine functions.
• nucleotides - building blocks of nucleic acids, DNA and RNA

Chemical composition in Plants

Elements

• In addition to the carbon, hydrogen and oxygen that make up the vast majority of both plant and animal cells, plants will contain nitrogen, phosphorus, potassium, calcium, magnesium, zinc, sulfur, chlorine, boron, iron, copper, manganese and molybdenum. Some of these are found in only very trace amounts, and the composition may vary between different types of plants.

Cell Wall

• A major difference between plants and animals is that plant cells are surrounded by a cell wall, which animal cells lack. The major component of the cell wall is cellulose, which is a polysaccharide, a large molecule made up of many smaller sugar molecules linked together. Glucose is the subunit in cellulose. In addition to cellulose, plant cell walls contain lesser amounts of hemicellulose and pectin; both of which are also large molecules made up of recurrent smaller subunits.

Chlorophyll

• Plants, unlike animals, can obtain energy directly from the sun, thanks to the extraordinary chemical chlorophyll. There are two main types of chlorophyll: a and b. Both are very similar and differ only in a small side chain within the large molecule. Like most chemicals involved in life processes, it's mostly carbon, hydrogen and oxygen. There are four nitrogen atoms within a chlorophyll molecule and, at the center of the molecule, one atom of magnesium. Chlorophyll is able to take energy in the form of sunlight, and chemically convert carbon dioxide and water into glucose and oxygen.

DNA and Protein

• Both plants and animals are eukaryotic, meaning the cells contain a nucleus at the center containing the genetic material. Although there are many differences between plants and animals, there is a remarkable similarity on this level. Plants, like animals, use DNA, consisting of the same sugar-phosphate backbone and using the nucleotide bases adenine, guanine, thymine and cytosine, to code for amino acids to construct proteins.