SELENIUM

normal serum level is 50-100 mg/day

Selenium dependent enzymes include glutathione Peroxidase and 5-de-iodinase. Selenium concentration in testis is the highest in adult.  It is very necessary for normal development and maturation of sperm.

The pH scale

An acidic solution is one in which [H+ ] > [OH- ]

•In an acidic solution, [H+ ] > 10-7 , pH < 7.

•A basic solution is when [OH- ] > [H+ ].

•In a basic solution, [OH- ] > 10-7 , pOH < 7, and pH >7.

• When the pH = 7, the solution is neutral.

•Physiological pH range is 6.5 to 8.0

BIOLOGICAL BUFFER SYSTEMS 

Cells and organisms maintain a specific and constant cytosolic pH, keeping biomolecules in their optimal ionic state, usually near pH 7. In multicelled organisms, the pH of the extracellular fluids (blood, for example) is also tightly regulated. Constancy of pH is achieved primarily by biological buffers : mixtures of weak acids and their conjugate bases 

Body fluids and their principal buffers

Body fluids                     Principal buffers

Extracellular fluids        {Biocarbonate buffer Protein buffer } 

Intracellular fluids         {Phosphate buffer, Protein }

Erythrocytes                 {Hemoglobin buffer}

The basic characteristics of enzymes includes

(i) Almost all the enzymes are proteins and they follow the physical and chemical reactions of proteins (ii) Enzymes are sensitive and labile to heat

(iii) Enzymes are water soluble

(iv) Enzymes could be precipitated by protein precipitating agents such as ammonium sulfate and trichloroacetic acid.

Biotin

 Biotin helps release energy from carbohydrates and aids in the metabolism of fats, proteins and carbohydrates from food.

RDA The Adequate Intake (AI) for Biotin is 30 mcg/day for adult males and females

Biotin Deficiency Biotin deficiency is uncommon under normal circumstances, but symptoms include fatigue, loss of appetite, nausea, vomiting, depression, muscle pains, heart abnormalities and anemia.