The Protein Structure

The Protein Structure
The basic structure common to all proteins is the peptide linkage which is formed by condensation the carboxyl group of one of amino acid with the amino group of another.

In this way chains are created, which contains only 3 amino acids, to complex polymers of 1000 or more.

The sequence in which amino acids are arranged in the peptide chain is known as the primary structure of the molecule.

The proper sequence of amino acids tends to be a critical factor in protein function.

In some heritable disease, such as sickle cell anemia, the defect is due to the genetic substitution of only one amino acid in the hemoglobin molecule.

Differences in sequence of three amino acids in insulin from different species, however, do not affect the activity of the hormone apparently, because this three amino acid sequence is not an active site of the molecule.

Biological activity of a protein, however, depends not only on the sequence of the amino acids but also on the spatial arrangement of the long peptide chain.

Although the peptide bond is the primary and also the strongest linkage ion the protein polymer, other peptides of bonding occur.

These additional linkages or secondary bonds are partly responsible or the arrangement of the molecule.
The Protein Structure

Rice and Nutrition

Rice and Nutrition
Rice may well be the most ancient of food grains, and next to whet, it is the grain grown in largest quantity throughout the world today.

It may be the major as aspect of a diet, or incorporated into the man dish, side dish, or dessert and is commonly used in the preparation of ready to eat breakfast cereals.

Rice is especially important to persons with wheat allergies and is commonly eaten as a first food by infants, as it offers the least cereal allergy.

Rice may be eaten as the whole grain, or polished shedding the bran. Generally, rice is polished during milling in order to remove the brown hull, which also removes some of the protein, vitamins and minerals. (The once-prevalent deadly disease beri-beri resulted from eating polished rice (thiamin removed in the milling process) as a staple food.)

Today, most white rice is enriched with vitamins and minerals, to add back nutrients lost in milling.

Unpolished, whole rice is more subject to flavor deterioration and insect infestation than polished, white rice.

The primary place of origin of rice is Southeast Asia, where an average of more than 200 pounds per person a year are eaten.

China, India, Japan and Vietnam are some of the major rice consuming countries.

Warmer climates with abundant water are ideal for rice growth. Larger crops are now being cultivated in California and the southern United States and a number of varieties of rice are now commonly available.

Sweet rice is more glutinous than other varieties and is used mostly for dessert such as rice pudding.

Long and short grain brown rice are also commonly available, with many varieties providing different flavors.

Besides just being boiled to be eaten with vegetables, tofu, fish and so on, rice an be popped and used as a breakfast cereal cream of rice, another breakfast cereal, is made form ground rice.
Rice and Nutrition

Functions of Carbohydrate

Functions of Carbohydrate
The main function of carbohydrate is to provide energy. Each gram of starch or sugar gives four calories to the body.

About 65 top 80 –percent of energy is supplied by the carbohydrates, mainly in the form of starch.

Some of this energy is used as glucose to supply immediate energy needs of the body, a small portion is stored as glycogen (about 350 g) mainly in the muscles and liver; and any excess intake is converted to fat and stored as adipose tissue.

Glucose is the source of energy for the central nervous system.

Another important function is to spare proteins for their main function of tissue building and maintenance. It is important to supply sufficient carbohydrates and fats to meet the essential energy needs of the body, otherwise proteins are metabolized to meet energy requirement of the body.

A third functions is related to proper utilization of fat from the diet. It is that fats burn in the flame of carbohydrates, indicating the need for major part of energy to be supplied in the form of carbohydrates.

Certain carbohydrates have special role in the body. Lactose aids the absorption of calcium, Ribose a five carbon sugar, is a part of the important compounds DNA and RNA.

Cellulose and other indigestible carbohydrates aid the movements of food through the digestive tract by their capacity to absorb water and help to maintain muscle tone.
Functions of Carbohydrate