COLORIMETER – PRINCIPLE, COMPONENTS, WORKING & APPLICATIONS

COLORIMETER – PRINCIPLE, COMPONENTS, WORKING & APPLICATIONS

PRINCIPLE OF COLORIMETER:

⇒ Colorimeter is based on the photometric technique which states that When a beam of incident light of intensity I₀ passes through a solution, a part of the incident light is reflected (I_r), a part is absorbed (I_a) and rest of the light is transmitted (I_t)

The mathematical relationship between the amount of light absorbed and the concentration of the substance can be shown by the two fundamental laws of photometry on which the colorimeter is based.

Beer’s Law

⇒ This law states that the amount of light absorbed is directly proportional to the concentration of the solute in the solution.

Lambert’s Law

⇒ The Lambert’s law states that the amount of light absorbed is directly proportional to the length and thickness of the solution under analysis.

PARTS OF COLORIMETER:

There are 5 essential parts in a calorimeter.

⇒ Light Source – The most common source of light used in colorimeter is a tungsten filament.

⇒ Monochromator – To select the particular wavelength filter or monochromators are used to split the light from light source.

⇒ Sample holder – Test tube or Cuvettes are used to hold the color solutions they are made up of Glass at the visible wavelength.

⇒ Photo Detector System – when light falls on the detector system, an electric current is generated, this reflects the Galvanometer reading.

⇒ Measuring device – The current from the detector is fed to the measuring device, the Galvanometer, shows the meter reading that is directly proportional to the intensity of light.

WORKING OF THE COLORIMETER:

⇒ When using a colorimeter, it requires being calibrated first which is done by using the standard solutions of the known concentration of the solute that has to be determined in the test solution.

⇒There is a ray of light with a certain wavelength that is specific for the assay is directed towards the solution. Before reaching the solution the ray of light passes through a series of different filters and lenses.

These lenses are used for navigation of the colored light in the colorimeter and the filter splits the beam of light into different wavelength and allows the required wavelength to pass through it and reaches the cuvette containing the standard or Test solutions.

It analyzes the reflected light and compares with a predetermined standard solution.

⇒ The galvanometer measures the electrical signals and displays it in the digital form. That digital representation of the electrical signals is the absorbance or optical density of the solution analyzed.

⇒ If the absorption of the solution is higher than there will be more light absorbed by the solution and if the absorption of the solution is low then more lights will be transmitted through the solution which affects the galvanometer reading and corresponds to the concentration of the solute in the solution.

APPLICATIONS OF THE COLORIMETER:

⇒ The colorimeter is commonly used for the determination of the concentration of a colored compound by measuring the optical density or its absorbance.

⇒ It can also be used for the determination of the course of the reaction by measuring the rate of formation and disappearance of the light absorbing compound in the range of the visible spectrum of light.

⇒ By colorimeter, a compound can be identified by determining the absorption spectrum in the visible region of the light spectrum.

Simple staining Microbiology for dmlt students

Simple Staining Procedure and its Mechanism:

Simple staining is a method of staining in which bacteria are stained by using a single stain.

Simple staining is also called as monochrome staining or positive staining.

Examples of simple stain are Methylene blue, Safranin, Malachite green, Basic fuchsin and crystal violet etc.

In simple staining procedure cell are uniformly stained.

Procedure of simple staining:

A clean grease free slide is taken .

A grease free slide is is made by first washing the slide with detergent wiping the excess water and the slide is passed through flame.

On these grease free slide smear is made by using a sterile wireloop and cell suspension.

These slide is allowed to air dry .

After air drying these slide is rapidly passed through a flame for three to four times for heat fixation.

After heat fixation the slide is placed on the staining rack and flooded with a particular stain (Methylene blue, Safranin, Malachite green, Basic fuchsin and crystal violet ) and these stain is allowed to react for three minutes.

Futher the slide is washed under running water.

The slide is air dried and washed under oil immersion.

Application :

Simple staining procedure stain bacteria easily and helps in observation under microscope.

It is useful in preliminary studies of morphological characters of cell that is its size, shape and arrangement.

Calculation of Specific Gravity

The Formula for Specific Gravity

The formula for specific gravity, given that the reference substance is water, is the density of the object divided by the density of the water. Here, we use the Greek symbol Rho to indicate density.

The specific gravity has no unitbecause the units of the numerator and the denominator are the same, so they just cancel each other out.

Methods to preservation of urine specimens- biochemistry notes for DMLT

 Five methods for preserving urine specimens, including their advantages and disadvantages.

• Preservation of specimen:

  • Urine is preserved in various methods like refrigeration and adding preservatives.

  • Preserving a specimen is significant for urine analysis.

  Methods to preserve urine specimens:

  • Refrigeration

  • Boric acid

  • Formalin (formaldehyde)

  • Sodium fluoride

  • Commercial preservative tablets

  Refrigeration:

  • It is the process of freezing or keeping the specimen in low temperatures to prevent pathogenic growth.

  • For 24 hours it prevents bacterial growth.

  Advantages:

  • Interference with chemical test does not occur.

  Disadvantages:

  • Refrigerated specimen forms amorphous phosphates and urates precipitation.
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• Ismail Tahasildar

Barrett’s esophagus: DMRT

Barrett’s esophagus is a condition in which the lining of the esophagus changes, becoming more like the lining of the small intestine rather than the esophagus. This occurs in the area where the esophagus is joined to the stomach.
It is believed that the main reason that Barrett’s esophagus develops is because of chronic inflammation resulting from Gastroesophageal Reflux Disease.
Barrett's esophagus are classified into four categories:
nondysplastic
low-grade dysplasia,
high-grade dysplasia, and frank carcinoma.

Barrett's esophagus is diagnosed by endoscopy: observing the characteristic appearance of this condition by direct inspection of the lower esophagus; followed by microscopic examination of tissue from the affected area obtained from biopsy.

Toxic Goitre: DMRT

A toxic nodular goiter (TNG) is a thyroid gland that contains autonomously functioning thyroid nodules, with resulting hyperthyroidism.

Examples of toxic goiters include diffuse toxic goiter (Graves disease), toxic multinodular goiter, and toxic adenoma (Plummer disease).

Diagnosing a goiter may also involve:
A.hormone test.
B.Antibody test.
C. ultrasonography
D. A thyroid scan
F. A biopsy

BONE TUBERCULOSIS: DMRT

BONE TUBERCULOSIS:
                     Bone TB occurs when the contract tuberculosis and it spreads outside of the lungs. Tuberculosis is normally spread from person to person through the air. After the contract tuberculosis, it can travel through the blood from the lungs or lymph nodes into the bones, spine, or joints. Bone TB typically begins due to the rich vascular supply in the middle of the long bones and the vertebrae.

Bone tuberculosis is relatively rare, but in the last few decades the prevalence of this disease has increased in developing nations partially as a result of the spread of AIDS. While rare, bone tuberculosis is difficult to diagnose and can lead to severe problems if left untreated.
When bone tuberculosis is more advanced,
some dangerous symptoms include:
neurological complications
paraplegia/paralysis
limb-shortening in children
bone deformities

Treatments include:
antituberculosis medications, such as rifampicin, isoniazid, ethambutol and pyrazinamide
surgery

Glycolysis Steps -DMLT Final year

Glycolysis is the metabolic process that serves as the foundation for both aerobic and anaerobic cellular respiration. In glycolysis, glucose is converted into pyruvate

Step 1: Hexokinase

The first step in glycolysis is the conversion of D-glucose into glucose-6-phosphate. The enzyme that catalyzes this reaction is hexokinase. In this step 1 molecule of ATP has been consumed.

Step 2: Phosphoglucose Isomerase

The second reaction of glycolysis is the rearrangement of glucose 6-phosphate (G6P) into fructose 6-phosphate (F6P) by glucose phosphate isomerase (Phosphoglucose Isomerase). this reaction involves an isomerization reaction.

Step 3: Phosphofructokinase

Phosphofructokinase, with magnesium as a cofactor, changes fructose 6-phosphate into fructose 1,6 -bisphosphate. The enzyme that catalyzes this reaction is phosphofructokinase (PFK).

Step 4: Aldolase

The enzyme Aldolase splits fructose 1, 6-bisphosphate into two sugars that are isomers of each other. These two sugars are dihydroxyacetone phosphate  (DHAP) and glyceraldehyde 3-phosphate (GAP).

Step 5: Triphosphate isomerase

The enzyme triophosphate isomerase rapidly inter- converts the molecules dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP). Glyceraldehyde phosphate is removed / used in next step of Glycolysis.

Step 6: Glyceraldehyde-3-phosphate Dehydrogenase

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) dehydrogenates and adds an inorganic phosphate to glyceraldehyde 3-phosphate, producing 1,3-bisphosphoglycerate. The enzyme that catalyzes this reaction is glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

 

Step 7: Phosphoglycerate Kinase

Phosphoglycerate kinase transfers a phosphate group from 1,3-bisphosphoglycerate to ADP to form ATP and 3-phosphoglycerate. by the enzyme phosphoglycerate kinase (PGK). we actually synthesize two molecules of ATP at this step.

Step 8: Phosphoglycerate Mutase

The enzyme phosphoglycero mutase relocates the P from 3- phosphoglycerate from the 3rd carbon to the 2nd carbon to form 2-phosphoglycerate.

Step 9: Enolase

The enzyme enolase removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvic acid (PEP).

Step 10: Pyruvate Kinase

The enzyme pyruvate kinase transfers a P from phosphor-enol-pyruvate (PEP) to ADP to form pyruvic acid and ATP Result in step 10. we actually generate 2 ATP molecules.

Steps 1 and 3 = – 2ATP
Steps 7 and 10 = + 4 ATP
Net “visible” ATP produced = 2

TCA Cycle - DMLT Final year

                                              It is also known as TriCarboxylic Acid (TCA) cycle. In prokaryotic cells, the citric acid cycle occurs in the cytoplasm; in eukaryotic cells, the citric acid cycle takes place in the matrix of the mitochondria. 

STEP 1: Formation of Citrate

The first reaction of the cycle is the condensation of acetyl-CoA with oxaloacetate to form citrate, catalysed by citrate synthase. 

STEP 2: Formation of Isocitrate

The citrate is rearranged to form an isomeric form, isocitrate by an enzyme acontinase.

In this reaction, a water molecule is removed from the citric acid and then put back on in another location.

STEP 3: Oxidation of Isocitrate to α-Ketoglutarate

In this step, isocitrate dehydrogenase catalyzes oxidative decarboxylation of isocitrate to form α-ketoglutarate.

In the reaction, generation of NADH from NAD is seen.

STEP 4: Oxidation of α-Ketoglutarate to Succinyl-CoA

Alpha-ketoglutarate is oxidized, carbon dioxide is removed, and coenzyme A is added to form the 4-carbon compound succinyl-CoA.

During this oxidation, NAD+ is reduced to NADH + H+. The enzyme that catalyzes this reaction is alpha-ketoglutarate dehydrogenase.

STEP 5: Conversion of Succinyl-CoA to Succinate

CoA is removed from succinyl-CoA to produce succinate.

The energy released is used to make guanosine triphosphate (GTP) from guanosine diphosphate (GDP) and Pi by substrate-level phosphorylation.

GTP can then be used to make ATP. The enzyme succinyl-CoA synthase catalyzes this reaction of the citric acid cycle.

STEP 6: Oxidation of Succinate to Fumarate

Succinate is oxidized to fumarate.

During this oxidation, FAD is reduced to FADH2. The enzyme succinate dehydrogenase catalyzes the removal of two hydrogens from succinate.

STEP 7: Hydration of Fumarate to Malate

The reversible hydration of fumarate to L-malate is catalyzed by fumarase (fumarate hydratase).

Fumarase continues the rearrangement process by adding Hydrogen and Oxygenback into the substrate that had been previously removed.

STEP 8: Oxidation of Malate to Oxaloacetate

Malate is oxidized to produce oxaloacetate, the starting compound of the citric acid cycle by malate dehydrogenase. During this oxidation, NAD+ is reduced to NADH + H+.

Proteins- Definition, Classification and Properties for dmlt ddt dotat and paramedical students

Proteins- Definition, Classification and Properties: 

Contents:

1. Definition of Proteins
2. Biological Importance of Proteins
3. Classification of Proteins.
4. Important Tests of Proteins
5. Estimation of Proteins

1. Definition of Proteins

Proteins may be defined as the high molecular weight mixed polymers of α-amino acids joined together with peptide linkage (-CO-N H-).
Proteins are the chief constituents of all liv­ing matter. 
They contain carbon, hydrogen, nitro­gen and sulphur and some contain phosphorus also.

2.Biologicalmportance of Proteins.

i.Proteins are the essence of life processes.

ii. They are the fundamental constituents of all protoplasm and are involved in the struc­ture of the living cell and in its function.

iii Enzymes are made up of proteins.

iv. Many of the hormones are proteins.

v. They are involved in blood clotting through thrombin, fibrinogen and other protein factors.

vi. They act as the defence against infections by means of protein antibodies.

3.Classificationof Proteins.

I. Simple proteins

(i) Albumins:

Soluble in water, coagulable by heat and precipitated at high salt concentrations.   Examples – Serum albumin, egg albumin, lactalbumin (Milk), leucosin (wheat), legumelin (soyabeans).

ii) Globulins:

Insoluble in water, soluble in dilute salt solutions and precipitated by half  saturated salt solutions.

Examples – Serum globulin, vitellin (egg yolk), tuberin (potato), myosinogen (muscle), legumin (peas).

(iii) Glutelins:

Insoluble in water but soluble in dilute  acids and alkalis. Mostly found in plants.

Examples – Glutenin (wheat), oryzenin (rice).

(iv) Prolamines: Insoluble in water and absolute alcohol  but soluble in 70 to 80 per cent alcohol.

Examples – Gliadin (wheat), zein (maize).

(v) Protamines:

Basic proteins of low molecular weight.  Soluble in water, dilute acids and alkalis,  Not coagulable by heat. Examples– Salmine (salmon sperm).

(vi) Histones:

Soluble in water and insoluble in very I dilute ammonium hydroxide.   Examples– Globin of hemoglobin and thymus histones.

II. Conjugated Proteins

(i) Nucleoproteins:

Composed of simple basic proteins (pro­tamines or histones) with nucleic acids,   found in nuclei. Soluble in water.

Examples – Nucleoprotamines and nucleohistones.

(ii) Lipoproteins:

Combination of proteins with lipids, such as fatty acids, cholesterol and   phospholipids etc.

Examples – Lipoproteins of egg-yolk, milk and cell membranes, lipoproteins of blood.

(iii) Glycoproteins:

Combination of proteins with carbohydrate (mucopolysaccharides).

Examples – Mucin (saliva), ovomucoid (egg white), osseomucoid (bone).

(iv) Phosphoproteins:

Contain phosphorus radical as a prosthetic group.

Examples – Caseinogen (milk), ovovitellin (egg yolk).

(v) Metalloproteins:

Contain metal ions as their prosthetic  groups. The metal ions generally are Fe, Co. Mg, Mn, Zn, Cu etc.

Examples – Siderophilin (Fe), ceruloplasmin (Cu).

III. Derived Protein

A. Primary derivatives

(i) Proteans:

Derived in the early stage of protein hydrolysis by dilute acids, enzymes or alkalis.     Examples– Fibrin from fibrinogen.

(ii) Metaproteins:

Derived in the later stage of protein hydrolysis by slightly stronger acids and alkalis.   Examples– Acid and alkali metaproteins.

(iii) Coagulated:

They are denatured proteins formed by the action of heat. X-rays, ultraviolet rays etc .   Example: Cooked proteins, coagulated albumins.

B. Secondary derivatives

(i) Proteoses:

Formed by the action of pepsin or trypsin. Precipitated by saturated solution of ammonium sulphate, incoagulable by heat.

Examples – Albumose from albumin, globulose from globulin.

(ii) Peptones: .

Further stage of cleavage than the proteoses. Soluble in water, incoagu­lable by heat and not precipitated by saturated ammonium sulphate solutions.

(iii) Peptides:

Compounds containing two or more amino acids. They may be di-, tri-, and porypeptides.

Examples – Glycyl-alanine, leucyl-glutamic acid.

Deliquescent AND Hygroscopic for ddt,dotat students

                         Deliquescent  AND  Hygroscopic:

Deliquescent substances are solid matter that can get dissolved by absorbing water vapor. The resulting solution is an aqueous solution.  This process is known as deliquescence. These deliquescent substances have a high affinity to water.
for example: sodium hydroxide, potassium hydroxide, ammonium chloride, sodium nitrate, calcium chloride, etc.

Hygroscopic:

Hygroscopic substances are solids that can absorb or adsorb water from its surroundings. When water vapor is absorbed by hygroscopic substances, the water molecules are taken into the spaces of the crystal structure. This causes the volume of the substance to increase. Hygroscopy can result in changes in the physical properties of the hygroscopic substances; such properties include color, boiling point, viscosity, etc.

Some examples: are Zinc chloride (ZnCl2), sodium chloride (NaCl) and sodium hydroxide (NaOH).