Question

Question 4-12 points Biologists use gel electrophoresis to sont DNA segments by size. DNA segments are placed at one end of a gel. DNA is negatively chargod (with a charge of two electrons per base pair). When you "run the gel" you are generating an electric field by connecting anodes and cathodes at the ends of the gel This causes the negatively charged DNA segments to move towards the positive electrode. After nunning the gel, smaller DNA segments have moved farther from the starting end The overall theme for this question is: Why do the smaller DNA segments move farther? Langer DNA Segment Shotw DNA Segment (a) Each base pair of a DNA molecule has a negative charge of-2e. Defining whatever variables you find appropriate, come up with an expression for i) the total charge of a DNA segment of N base pairs (1 point) i) the total mass of a DNA segment of N base pairs(1 point (b) To understand how electrophoresis might work we will start with a simple model. We wi目ignore the gel and assume that the only force acting on the DNA segments is the electric force due to a constant electric field Starting with a free body diagram, produce an oquation that describes how the electrostatic force acts on DNA segments of decide how this force would affect the motion of different-sized segments of DNA. Does this explain how electrophoresis separates DNA segments by size? (2 points) diffierent sizes Use Newton's 2 law to Continues on the mest page.. HW 2 PH 142 Total: 35 Points Due:01/25/19 at 5pm (c) In reality the gel exerts a significant drag force on the DNA segments. Drag forces are proportional to the cross-sectional area of an object, as we saw last semester. Here we want to learn something about the structure of DNA in solution based on the behavior observed in the electrophoresis gel. We will choose between three models for the structure of DNA that describe how its size and shape change with the number of base paars

Answer 1