Biochem Essay

An introduction to Biochemistry

Biochemistry is the study of the molecules that facilitate the processes in a living organism, the mechanism in which the molecules achieve this and the energy expenditure required for each process. These molecules are more specifically known as biomolecules. Every aspect of life depends upon the chemical makeup of cells and on the chemical properties of the remarkable molecules found within the cells of our body. Living organisms have four major characteristics that identify them as "living". They are all made up of cells, they are able to reproduce, they are able to adapt to changing environments and evolve and finally they are able to metabolise what they consume.

Carbohydrates, lipids, proteins, and nucleic acid are the four major classes of biomolecules present within our body. These are primarily composed of carbon, hydrogen, oxygen and nitrogen. The body also requires seven essential minerals which are calcium, magnesium, phosphorus, sodium, potassium, sulfur, and chlorine. There are also a group called trace elements that are not required in amounts of less than 100mg a day, and these include iron, copper, iodine and zinc. We will concentrate on the four major organic substances. Each of the four are called macromolecules because they are large and made up of many small subunits called monomers.

Carbohydrates

Simple sugars are the basic building blocks of carbohydrates. These sugars include glucose, fructose and ribose. These simple sugars are called monosaccharides. These subunits can join together to form short strings called oligosaccharides; they do this by a process called dehydration synthesis. Sucrose and maltose are examples. Polysaccharides are chains made up of thousands monosaccharides joined together. Examples of polysaccharides are glycogen (storage carbohydrate) in animals and cellulose in plants. In animals, carbohydrates are used as the major energy source.

Lipids

The major characteristic of lipids is that they are relatively insoluble in water. The subclasses of lipids used in our body are triglycerides, phospholipids and steroids. Triglycerides, which are generally more known as fats, are used as energy storage molecules. They are composed of a molecule of glycerol and 3 fatty acids. Fats fall into two major categories: saturated fats, which are solid at room temperature, and unsaturated fats (oils), which are liquid at room temperature.

Phospholipids are the primary component of cell membranes. They are made up of 1 glycerol molecule, 2 fatty acids, a phosphate group and another positively charged group. Finally, steroids do not have the same general structure as other lipids but they are still classed as lipids due to their insolubility in water. They consist of a backbone of three 6-member carbon rings and one 5-membered carbon ring. Examples of steroids include cholesterol, and some hormones, including the sex hormones testosterone and estrogen.

Proteins

Proteins are constructed from subunits called amino acids. There are 20 different amino acids all together. Each amino acid is made up of an amino group (NH3), a carboxyl acid group, C-H group and an additional "R" group. A single string of 3 to 100 amino acids is called a polypeptide. A