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PinkMonkey Online Study Guide-Biology

Importance of proteins in metabolism : Proteins are the building materials forming the main constituents of protoplasm. They are also used in repairing any wear and tear of the body. Various enzymes and some hormones are protiens which control the biochemical process taking place in all cells. In addition, protiens regulate duplication and translation of DNA and RNA into thier protien gene products. Excess protein, unlike carbohydrates which are stored in the body, is broken down in the liver to form urea which is expelled in the form of urine. The remaining parts are utilized for forming other complex food substances by inter-conversion.

(c) Fats and Oils (Lipids) : Fats and their derivatives are collectively called lipids. Fats are the compounds of fatty acids and glycerol. They are composed of C, H and O but there is less oxygen than in carbohydrates.

There are mainly three types of lipids, namely the simple lipids such as fats and waxes, the compound lipids such as phospholipids and glycolipids and the derived lipids such as steroids which include cholesterol, sex hormones like estrogen, androgen, etc.

Fats are highly concentrated energy foods which produce 9.5 Kcal of energy per gram, more than twice produced by carbohydrates. They are obtained from butter, cream, oil, nuts, fish, etc.


Importance of lipids in metabolism : Fats are used in the growth of living bodies. They mainly serve as compact fuel molecules because they yield more energy per unit weight than any other food substance. Fats also serve as reserve food. In animals living in cold regions, fats form an insulating coating within the body. In the case of animals like camels living in deserts, oxidation of fats yields metabolic water which enables the animal to remain without ingesting water for several days.

(d) Vitamins : These are organic food factors which are essential for healthy and well balanced growth of the body. Small amounts of vitamins are sufficient for the normal functioning of the body, as they are usually recycled in the bodyo. If vitamins are not taken in sufficient quantities, it may lead to various "deficiency diseases" as shown in the table below.

Vitamins are not synthesized by animals but obtained directly or indirectly from plants. Vitamins are A, B-complex, C, D, E and K of which B-complex and C are water soluble while A, D, E and K, are fat-soluble.

(e) Minerals : These are necessary for the body to perform its normal functions. About 4% of our body weight is formed by minerals. Fresh fruits and green vegetables are rich in minerals. A few important minerals needed for our body functions are given below:

(i) Calcium and Phosphorus: They are essential for the development of bones and teeth. Besides, calcium is also useful in clotting of blood and phosphorus is necessary in the formation of energy rich molecule called ATP.

(ii) Iron: It is essential for the formation of red pigment hemoglobin of blood. Deficiency of iron causes anemia.

(iii) Iodine: It is necessary for the proper functioning of the thyroid gland. A deficiency of iodine leads to simple goiter.

(iv) Potassium and Sodium: These are the main constituents of body fluids, nerve cells and blood plasma, and are often ingested in mineral forms.

(v) Magnesium: This is useful in the activation of many enzymes.

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Table of Contents

16.0 - Introduction
16.1 - Nutritional Requirements, Imbalances and Deficiency Diseases
16.2 - Organs of Digestion and Physiology of Digestion

Chapter 17





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