NBSC'S

REASONING BIOCHEMISTRY

BY

DR. DIWAN

REASON THIS:

01. "We are living in very high concentration of water."

• Concentration of water in one liter of water is 55.5M, because the Specific Gravity of water at 25oC is 1.000. So one liter of water will have weight of 1000gm. And 18gm of water makes 1M so 1000/18 = 55.5M of water will be present in one liter of water.
• Glucose content of normal person is 90mg/dl and molecular weight of glucose is 180 so the concentration of glucose is 5.0mM in 100ml, whereas the concentration of water in 100ml is 55500mM
• So we live with a very high water to glucose ratio of 55500:5

02. "The expansion of water on freezing has overwhelming consequences for
life on earth. What will happen if water starts contracting upon freezing?"

· The water upon contraction will become denser and the ice would then sink to the bottoms of lakes and oceans, rather than floating.

· This ice would be insulated from sun so that oceans, with the exception of thin surface layer of liquid in warm weather, would be permanently frozen solids.

· The reflection of sunlight by these frozen oceans and their cooling effect on
the atmosphere would ensure that land temperatures would also be much
colder than at present.

· That is, the earth would have permanent ice age, and life evolved in the ocean, it seems unlikely that life could have developed at all if water contracted upon freezing.

03. Amino acids as well as proteins can buffer both in the acid and alkaline solutions.

• A solution of weak acid/strong acid and its salts forms buffer. E.g. CH3COOH and CH3COONa, NaH2Por and Na2HPO4, KCl and HCl etc
• Amino acids are amphoteric in nature because of amino and carboxylic groups:
• If we take 500 moles of an amino acid and add 250 moles of HCl, we will be left with 250 moles of amino acid and 250 moles of amino acid hydrochloride will be formed.
• In such a mixture amino acid hydrochloride is proton donor and unreacted amino acid is proton acceptor, which can be buffered in acid range.
• Similarly, amino acid can form buffer in alkaline side because of carboxylic group, which is similar to sodium acetate and acetic acid system.

· Proteins are composed of amino acids, some amino acids are basic and some are acidic. The extra carboxylic and amino groups can also form buffer.

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