hey guys quick biker mr basics here let's talk about electrophoresis the term electrophoresis means movement of charged particles dispersed in liquid medium under the influence of an electric field the movement of particles under electric field was first discovered by russian professor when he was trying to study the effect of electric field on dispersed clay particles he found that when electric field is switched on the clay particles in water shows migration electrophoresis is widely used for the separation of biomolecules such as dna rna and protein this is because most of the biomolecules have positive or negative charge for example dna and rna usually have net negative charge whereas proteins can either have positive or negative charge depending on the amino acids electrophoresis is carried out in a buffer and the electric field is applied using electrodes which are attached with the power pack remember the power pack shows two readings one is the voltage which is the potential difference across the electrodes and other is the current which is flow of electricity across the electrodes during electrophoresis the distance between the two electrodes is an important factor to be considered this is because electric field between the electrodes is calculated as the ratio of potential difference across the electrodes and the distance between them the unit of electric field will be volts per centimeter now while carrying out electro forces the measurement of electric field is very important this is because the electrophoresis apparatus comes in various size let's understand this with an example if the distance between the two electrodes is 10 centimeter and the potential difference across electrodes is 100 volts then the electric field will be 10 volts per centimeter if the distance between the two electrodes is 20 centimeter and the potential difference across the electrodes is 100 volts then the electric field across electrodes will be 5 volts per centimeter now if you're carrying out agarose shell electro forces of dna then electrophoresis will be completed in about 15 to 20 minutes in the first case however in the second case because the electric field is half the time taken for completion of electro forces will be doubled hence all research publications will always mention electric field while describing electro forces now besides voltage and electric field the other important parameter to be considered while carrying out electro forces is the current the current is measured in milliamps the measurement of current and voltage is important because the heat generated during electrophoresis depends on the current voltage and the total time for which electro forces is carried out mathematically this is expressed as h is equal to vit here h is the heat v is the voltage across the electrodes i is the current and t is the time for which electrophoresis is carried out now voltage v is equal to ir your i is the current and r is the resistance in electrophoresis the resistance r depends on the type of buffer used the ionic strength of buffer and the gel used during electrophoresis if we substitute this in the above equation then we get h is equal to i square rt look at this term carefully this shows that heat will increase four times if the current passing between the electrodes doubles hence it is always advised to carry out electro forces at low current in order to avoid excess heat generation electrophoresis can be of several types such as paper electrophoresis capillary electrophoresis agarose gel electrophoresis sds page pulsed fill electro forces and two dimensional electrophoresis let's see each of them paper electrophoresis paper electrophoresis is one of the simplest electrophoresis technique because the separation is carried out on the piece of paper for this a strip of filter paper is taken and its ends are dipped in a tank filled with buffer once the paper strip becomes wet the sample is loaded when an electric current is switched on the sample molecules are separated based on their net charge agarose gel electrophoresis agarose gel electrophoresis is widely used for the separation of dna and rna the agarose shell has small wells where the samples are loaded because dna and rna have negative charge the wells of agarose gels are kept towards the negatively charged electrodes the movement of dna or rna occurs from negative to positive electrode the dna fragments which are small in size migrates fast as compared to the dna fragments that are large capillary electrophoresis as the name suggests the electrophoresis is carried out in a capillary tube the ends of capillary tube are immersed in the tank filled with buffer when the electric field is switched on the ions in the sample starts moving the ends of capillary tube has a detector system which detects the presence of sample by uv absorbance ir absorbance or by change in the refractive index sds page sds page is widely used for the separation of proteins here the electrophoresis is carried out in a vertical unit to the electro forces 2d gel electrophoresis is widely used for the separation of proteins in the first step the proteins are separated by a technique called isoelectric focusing in this method the proteins are resolved in a gel with ph gradient the separation of proteins occurs on the basis of their isoelectric ph in the next step the gel used in isoelectric focusing is used with sds page gel to carry out electrophoresis in second dimension pulsed fill gel electrophoresis pulsed field gel electrophoresis is widely used for the separation of chromosomes or very large dna fragments in this method four electrodes are used the electrodes apply alternating electric field which is at an angle of 120 degrees the alternating electric field across the diagonal allows separation of large dna fragments and chromosomes you