Isoelectric pH.

• It is the pH at which biomolecules exist as dipolar ion possessing same amount of positive and negative charge on their surface with net zero.
• Biomolecules contain different ionizable groups on their surface.
• Depending on the pH of solution these ionizable groups act either as proton donor or as proton acceptor and thereby express charge on their surface.
• At one definite pH called isoelectric pH, every biomolecule expresses both the charges on its surface in equal amount and exists as zwitter ion, when the net charge on the surface of biomolecule is zero because positive and negative charge equalize each other. So zwitter ions are electrically neutral without any electrohoretic mobility during electrophoresis.
• At pH below the isoelectric pH biomolecules accept protons from the medium and exist as cations with positive charge on their surface and at pH above the isoelectric pH biomolecules release proton to the medium and exist as anions with negative charge on their surface. 

pH of a solution.

P^H is the negative logarithm of hydrogen ion concentration of a solution, when H⁺ concentration is expressed in terms of molarity

 

[H+] in mol/L	Calculation of pH	pH
10-7	-log 10-7	7
10-8	-log 10-8	8
10-3	-log 10-3	3

What is free acidity and what is titratable acidity.

Free acidity:

• Free acidity of a solution is its instant H ion concentration measured without any manipulation.
• Free equimolar concentration of strong acid and weak acid, the free acidity will be very high in strong acid solution compared to that in weak acid solution because strong acids are completely dissociated and weak acids are partially dissociated into hydrogen ions.

Titratable acidity:

• Titratable acidity of a solution is its total H ion concentration that would be if the acid was allowed to ionize totally to hydrogen ion following its titration with alkali.
• For equimolar concentration of strong acid and weak acid the total hydrogen ion concentration of both the solution will be same at the end of complete ionization following titration with alkali.
• Very small amount of weak acid usually ionize to hydrogen ion and majority fail to ionize. During titration when alkali is added to the medium, the hydrogen ion concentration of the medium decreases which facilitate the unionized weak acid to ionize completely to hydrogen ion.
• Equimolar concentration of strong acid and weak acid differ with respect to free acidity, but they are same the respect to the titratable or total acidity.        

What is Amphoteric substance?

These are the substances which can act both as acid as well as base in different situation.

Properties of alkaali.

• Alkali are metallic hydroxides of alkaline metals, which in solution ionize to hydroxyl ions that can bind H to form H2O and thereby can remove hydrogen ion from solution.
• Strong alkalis are those which rapidly and almost completely ionize to hydroxyl ions that quickly remove hydrogen ion from solution.
• Weak alkalis are those which slowly and partially ionize to hydroxyl ions that slowly remove hydrogen ion from solution.
• In fact all alkalis are also regarded as base, but all bases are not alkalis. 

Properties of Base.

• Bases are proton acceptor in aqueous solution.
• Bases may be charged particle or may be without charge.
• Strong bases are those which have greater tendency to accept proton. They bind rapidly and strongly with strongly with proton, so quickly remove from solution.
• Weak bases are those which have very low tendency to accept proton. They bind slowly and weakly with proton, so slowly remove proton from solution.
• Conjugate acid of a base is the acid formed by that base after accepting proton. So conjugate acid of a strong base is weak and that of a weak base is strong.

Properties of Acid.

• Acids are proton donor in aqueous solution.
• Acids are molecules having hydrogen atom and capable to release hydrogen ion in aqueous solution.
• Acids may be the molecular species with positive charge or negative charge or may be without charge.
• Conjugate base of an acid is the remaining anionic part of an acid after removal of proton from that acid.
• Strong acid is the acid which rapidly and completely ionizes into H+ and its conjugate base in solution.
• Weak acid the acid which slowly and partially ionizes into hydrogen ion and its conjugate base in solution.
• For strong acid degree of dissociation and dissociation constant is high with low pK value. Conversely for weak acid degree of dissociation and dissociation constant is low with high pK value.
• In case of strong acid the conjugate base shows less affinity to proton because of which they can rapidly and completely ionize to proton. So conjugate bases of strong acids are weak in nature. On the other hand, in case of weak acid the conjugate base shows strong affinity to proton because of which they partially ionize to proton. So conjugate bases of weak acids are strong in nature. 

Radiation hazard

Radiation hazards are as follows:

1. Immediate hazards
• Bone marrow depression
• Immune suppression
• Damage to intestinal mucosa causing diarrhea and malabsorption.
• Baldness
• Rough and scaly skin
• In pregnancy: Fetal growth retardation, congenital malformations of fetus, fetal death.
2. Delayed hazards
• Carcinogenesis
• Sterility
• Cataract
3. Genetic defects
• DNA damage
• Mutation

Name the radio-sensitive tissue.

The following tissues are sensitive to radiation. These are mostly rapidly dividing tissues.

1. Bone marrow
2. Gonads
3. Lymph node
4. Skin
5. Intestine.

What is radioactivity? Clinical use of radioactive isotope.

Radioactivity:

It is the spontaneous emission of accelerated particles(radiation) from an unstable isotope by radioactive decay.

Clinical use of radio active isotope:

A. Diagnostic use

1. Iodine uptake test for diagnosis of thyroid disorders.
2. Radio immune assay of hormones for diagnosis of hormone disorders.
3. Organ scanning e.g. bone scan, brain scan, thyroid scan.
4. Absorption test e.g. for iron. vitamin B12
5. Isotope renogram for mesurement of GFR and renal clearance.
6. RBC life span measurement.

B. Therapeutic use, e.g. radiotherapy in treatment of malignancy.

C. Use in tracer technique: isotopes are used as tracer in metabolic studies to outline the metabolic pathways.

D. Measurement of volumes and spaces. e.g. ECF volume, Blood volume, plasma volume, RBC volume.

E. Measurement of regional blood flow. e.g. Cerebral blood flow, coronary blood flow, renal blood flow.

F. Sterilization of medical instruments.

Isotope: Definition, Types.

Definition:

• Atoms with same atomic number (number of proton), but different atomic weight (number of protons and neutrons).
• Atoms of same element with different atomic weight.

Types of isotope:

1. Stable isotope
• Stability of an isotope depends on the definite neutron to ration which is specific for a specific atom.
• In atoms of low atomic weight stability is usually achieved with neutron to proton ration around one.
• In atoms of high atomic stability is usually achieved with more neutron than proton
• Neutrally occurring isotopes of most of the predominant elements are stable isotopes.
2. Unstable isotope
• These are the isotopes having neutron to proton ration far away from its stability ratio.
• Neutrally occurring isotopes of heavy elements are usually unstable
• Rarely some naturally occurring isotopes of lighter elements can also be unstable
• Unstable isotopes tend to become stable by radio active decay

What is Epimer?

Epimer:

Epimers are the optical stereoisomers which differ with respect to the spatial configuration around only one asymmetric carbon out of more than one asymmetric carbon in the molecule.

 e,g.  Glucose and Mannose (they are C2 epimers)
         Glucose and Galactose (they are C4 epimers)

Isomer: Definition, Types.

Isomer:

Definition:

Isomers are substances having same molecular (chemical) formula, but different structure or having
same molecular formula and identical structural form, but different spatial configuration around one
or more carbon. Isomerism is the processes of formation of isomers.

Types of isomer:

1. Structural isomer
2. Stereo isomer (Space isomer)
• Geometric isomer
• Cis variety
• Trans variety

•  Optical isomer
• Optical enantiomers
• Diasteroisomers

Structural Isomer:

These are the substances having same molecular (chemical) formula, but different structure. These
type of isomers differ with respect to physical and chemical properties.
e.g.     CH3-CH2-CH2-CH3 (Butane)
           
                     CH3

           CH3-CH-CH3 (Isobutane)

Stereo Isomer (Space Isomer)

Substances having same molecular formula as well as identical structural form, but different with
respect to the spatial configuration of atoms or groups around one or more carbon. This type of
isomers sometimes shows identical physical and chemical properties.
Spatial configuration means
o Arrangement of atoms or groups around a carbon in relation to space,
o Three dimensional space relationship of atoms or groups around a carbon.

Types of stereo isomer:

1. Geometric isomer
2. Optical isomer
• Optical enantiomers
• Diastereoisomers

What is filtration?

Filtration:

It is the process by which fluid is forced out through a membrane or other barrier because of pressure
difference on the two sides of membrane. 

• Filtration at glomerular membranes of kidney that forms filtrate and urine.
• Filtration at arterial end of capillary that allows exit of fluid with nutrients out of blood vessel to reach the cells.

What is dialysis? Importance of dialysis.

Dialysis:

• It is one of the methods used to separate colloids and crystalloids from their mixture.
• The principle of dialysis is based on the fact that, crystalloid substances in solution can pass through semipermeable membrane while colloid particles cannot.
• Semipermeable membrane used in dialysis may be parchment membrane, cellophane membrane, cellulose nitrate, cellulose acetate etc. These are called dialyzing membrane (dialyzer) usually in the form of an elongated tube or of a bag.
• Dialyzing membrane acts as a sieve retaining the larger particles. Mixture of crystalloid and colloid is placed inside the tube or bag of diaylizer and then suspended in a vessel containing dialysis fluid. Dialysis fluid is prepared without the crystalloid substances which are to be separated. The crystalloid particles from the mixture will diffuse out to the dialysis fluid through the dialyzer down their concentration gradient, but colloids will retain within the dialyzer. Dialysis fluid is changed either periodically or continuously as the crystalloid particles diffuse out from the interior of the dialyzer into the surrounding dialysis fluid.

Importance of dialysis:

• It is used as artificial kidney for treatment of renal failure. In renal failure the crystalloid  uremic toxins, (e.g. urea, creatinine etc.) accumulate in blood since kidney fails to excrete them. So by the process of dialysis it is possible to remove these uremic toxins from blood, which allows the patients of renal failure to survive.
• It is used for treatment of hyperkalemia.