Macronutrients and Micronutrients


Macronutrients:
With a few exceptions, heterotrophs require organic molecules such as carbohydrates, lipids and proteins in their diets. Enzymes breakdown these molecules into components that can be used for energy production or as sources for the “binding blocks” of life.

Carbohydrates: Carbon and energy from sugars and starches. The main dietary source of energy for heterotrophs is carbohydrates. Most carbohydrates come from plant sources. Various sugars (mosachharides) can meet this dietary need. Carbohydrates also are a major carbon source for use in organic compounds. Many plants also supply cellulose (polysaccharide) that human and other animals (except herbivores) cannot digest. Cellulose is called dietary fibre. It assists in the passage of food through the alimentary canal of mammals. Cellulose may also reduce the risk of cancer of the colon, because the mutogen and reduced if faecal elimination is more frequent.

Lipids: Highly compact energy – storage nutrients. Neutral lipids (fats) or triacyl glycerols are contained in fats and oils meat and dairy products, nuts and some fruits and vegetables high in fats such as avocados. Lipids are the good source of food energy. They produce about 9 calories (K. Cal) of usable energy per gram more than twice the energy available from equal mass of carbohydrate or protein.

Many heterotrophs have dietary requirement for lipids e.g. many animals require unsaturated fatty acids (e.g. linoleic acid, limolenic acid and arachidonic acid). These fatty acids act as precursor molecules for synthesis of steroids e.g. cholesterol. The steriols are also required for the synthesis of steroid hormones and cholesterol, which is a part of cell membranes. Other lipids insulate the bodies of some vertebrates and help maintain constant temperature proteins. Basic to the structure and function of cells. Animal sources of protein are other animals and milk. Plant sources are beans, peas and nuts. Proteins are needed for their amino acids which heterotrophs use to build their own body proteins.

Micronutrients:
They are usually small ions, organic vitamins, inorganic minerals and molecules that are used repeatedly in enzymatic reactions or as parts of certain proteins (e.g. copper in hemocyanin and iron in haemoglobin). Animals cannot synthesize them rapidly. Thus they must be oblaived from the diet.

Minerals: Some minerals are needed in large amount and are called essential minerals or macro-minerals. E.g. sodium and potassium are vital to the working of nerve and muscle in animal’s body. Animals lose large sodium, in the urine every day. Animals that sweat to help regulate body temperature lose sodium in their sweat. Daily supply of calcium is needed for muscular activity and with phosphorus for bone formation.
Other nutrients are known as trace minerals or micronutrients. Animals need these in only very small amount for various enzymatic functions.

Vitamins: Normal metabolic activity depends on small amount of more than a dozen organic substances that occur in many foods in small amount and necessary for normal metabolic functioning.
Vitamins may be water soluble or fat soluble. Most water soluble vitamins such as B vitamins and vitamin C are coenzymes needed in metabolism. The fat soluble vitamins have various functions. The dietary need for vitamin C and the fat soluble vitamins (A, D, E and K) tends to be limited to the vertebrates vitamin requirement vary in different vertebrates.

Comments

Post a Comment

Popular posts from this blog

Compare the anatomy of Bifacial and Isobilateral leaves

BIFACIAL LEAF: It is also called dorsiventral leaf. This leaf is more strongly illuminated on upper surface than on lower surface. This unequal illumination induces a difference in the internal structure between upper and lower sides. Its internal structure shows: (1)        Upper Epidermis This is single layer of cells with thick cuticle which checks excessive evaporation of water from the surface. It does not contains chloroplasts, stomata are also absent. (2)        Lower Epidermis This is also single layer but with a thin cuticle. It bears many stomata, two guard cells of which contain some chloroplast, none are present in the epidermal cells. Internal to each stomata is large cavity called respiratory cavity. Lower epidermis of leaf is meant for exchange of gases (oxygen and carbon dioxide) between the atmosphere and the plant body. Excess water also evaporates from lower epidermis. (3)...
Read more

osmoregulation in terrestrial and aquatic animals

Mechanism of osmoregulation is very important for all groups of animals whether inhibting land or water. Unlike plant cells, animal cells when placed in hypotonic solution burst due to the continuous absorption of water. On the contrary they would shrink and die if constantly placed in hypertonic solution. Normally uptake and loss of water are in balance for proper survival of cell. (1)        Osmoregulation in terrestrial animals: Terrestrial animals are more likely to loose water by evaporation through their permeable surfaces exposed to amsophere. Among various animal groups only Arthropods and vertebrates became the most successful land dwellers. They have developed number of strategies to maintain osmoregulation of their body fluid. (a) Water proof external coverings: To prevent water loss through external surfaces, vertebrates like reptiles, birds and mammals have water proof keratinized epidermis. Similarly the insects have developed...
Read more

Autobiographical elements in A Farewell to Arms

Introduction Some, literature can be satisfactorily read and discussed taking the author into account. Other literature seems inseparable from the person who created it. To an extraordinary degree Hemingway and what he has written exist in a synergetic relationship, reinforcing and fulfilling each other; he has created a personal legend which serves as an ambience in which we read him. Autobiographical Touches The novel A Farewell to Arms autobiographical elements. The love-affair between Fredric and Barkley, the hero’s injury in the battlefield, his despair and frustration, the hero’s separate peace with life are some of the characteristics of Hemingway’s life. Hemingway himself had received the injury caused by the mortar-shell at Fossalta, and he was admitted into the Milan hospital for recuperation in the late summer and autumn of 1918. He fell in love with the nurse in the Milan hospital. Carlos Baker has thrown light on this fact. In A Farewell to Arms Hemingway was d...
Read more