Transmission electron microscope- examine viruses or the internal ultrastructure in thin sections of cells

#Id: 2487

#Unit 13. Methods in Biology

Acrylamide gels can be made with a content of between 3% and 30% acrylamide Low concentration are used to where free movement of the proteins is required without any noticeable frictional effect such as flat-bed isoelectric focusing or the stacking gel system of an SDS–polyacrylamide gel.

#Id: 2488

#Unit 13. Methods in Biology

Low-percentage acrylamide gels are also used to separate DNA. Gels of between 10 and 20% acrylamide are used in techniques such as SDS–gel electrophoresis, where the smaller pore size now introduces a sieving effect that contributes to the separation of proteins according to their size. 

#Id: 2489

#Unit 13. Methods in Biology

Sodium Dodecyl Sulfate (SDS)-Polyacrylamide Gel Electrophoresis is based on the separation of proteins according to size, it can also be used to determine the relative molecular mass of proteins.

#Id: 2490

#Unit 13. Methods in Biology

SDS (H3C-(CH2 )10 –CH2 -OSO3 – Na+ ) is an anionic detergent used to create negative on sample  On average, one SDS molecule binds for every two amino-acid residues.

#Id: 2491

#Unit 13. Methods in Biology

SDS–PAGE are firstly boiled for 5 min in sample buffer containing - mercaptoethanol or dithiothreitol ( DTT) and SDS. Mercaptoethanol or DTT reduce any disulfide bridges

#Id: 2492

#Unit 13. Methods in Biology

In conventional discontinuous gel electrophoresis two type of GEL system is used on top with comb there is a stacking gel with pH 6.8 and below resolving with gel pH 8.8 phenomenon known as isotachophoresis.