The process of gel electrophoresis‼️ Gel electrophoresis allows you… — Biotechnology Books & Pdf — TG.ME

The process of gel electrophoresis‼️ Gel electrophoresis allows you to take DNA fragments prepared using restriction endonucleases or polymerase chain reaction and separate them based on their size. Gel electrophoresis is a laboratory technique used by scientists to measure the size of DNA fragments. It is typically used after a sample of DNA has been cut up using restriction endonucleases or after a short sequence of DNA has been amplified using the polymerase chain reaction. The process of gel electrophoresis is described in the following steps: 1 The DNA samples are placed in the wells at one end of the gel using a micropipette. A standard ladder of DNA fragments with known sizes is also typically loaded into one well. This is required for estimating the size of any unknown DNA fragments by comparing them to the known fragments in the standard ladder. The gel is made of agarose, a sponge-like jelly that is filled with tiny pores to allow movement of the DNA fragments. This agarose gel is immersed in a buffer solution which helps carry an electric current. 2 An electric current is passed through the gel using two electrodes – one positive, one negative. The negative electrode is positioned near the wells and the positive electrode is at the opposite end of the gel. Since DNA is negatively charged due to the phosphate backbone, it is attracted to the positive electrode. When the electrical current is applied, DNA fragments will move from the wells, through the tiny pores in the agarose gel, towards the positive electrode. 3 Smaller DNA fragments move faster through the gel and so travel further than larger fragments, which don’t move as easily through the pores in the agarose. After a few hours, the current is switched off and the DNA fragments stop moving in the gel and settle into bands. The DNA fragments are now separated based on size. 4 DNA is difficult to see with the naked eye so the gel is stained with a fluorescent dye such as ethidium bromide, allowing the bands of DNA to be visualised under an ultraviolet (UV) lamp. This dye can be included in the gel before the experiment or applied after. When gel electrophoresis separates DNA fragments based on size, long fragments of DNA collect in bands of DNA near the well, while shorter fragments form bands further from the well. So, if person A’s allele for eye colour is 10 kb long, and person B’s allele for eye colour is 15 kb long, person A’s band will move further from the well. If they shared the same allele (e.g. person A and C), the bands would end up at the same distance from the well.