Sucrose molecules contain a number of polar oxygen-hydrogen bonds, each with an effective positive or negative charge. In a sugar crystal, a number of sucrose molecules are held together by attraction between these polar bonds, with negatively charged bonds attracting positively charged bonds and vice-versa. This attraction holds the sugar together in solid form, but when sugar enters water, the polar bonds …show more content…
It is based on the principle that nucleic acids, like DNA and RNA, are negatively charged. This means that if you put nucleic acids in an electric field, they will migrate away from the negative end of the field and toward the positive end. The nucleic acids are placed inside the gel for two main reasons. One, the gel is a way of holding them to know where they are. Two, the migration needs to occur in a manner that allows for the separation of different-sized pieces of DNA or RNA. The gel has many microscopic holes through which the nucleic acids wiggle as they migrate within the electric field. The smaller the nucleic acid sequence, the easier it is for it to wiggle through the holes. So, smaller pieces of DNA and RNA run through the gel faster than larger pieces. Returning to our forensic science example, this means that the individual pieces of DNA in each sample are sorted within the gel—the larger pieces appear at the top of the chamber and the smaller pieces appear at the bottom of the chamber. The scientist compares the pattern of the pieces of the crime scene DNA to the pattern of the suspect's' DNA and looks to see if there is an exact