Lab 8

Question 1

What is the charge of DNA? + or -?

Answer 1

Negative due to the phosphate backbone

Question 2

What is the gel made from? what does it “look like” at a molecular level?

Answer 2

the gel is made up of agarose, a polysaccharide extracted from the cell wall of algae. The gel looks like a matrix which the DNA molecule has to find its way through.

Question 3

What is the ‘loading die’ used for? what does it contain? what are the functions of the individual ingredients.

Answer 3

sucrose loading die is used. The sucrose makes the sample more dense than the surrounding buffer; thus, keeping the sample in the well. The die made of bromophenol blue helps in loading the sample into the blue. The dye also runs at a known speed which is about the same speed as a 500bp DNA fragment and lets us know when to stop the electrical current.

Question 4

Which DNA fragments will travel the farthest during gel electrophoresis?

Answer 4

Short ones as they can find their way through the matrix easier.

Question 5

What is a ‘DNA’ ladder?

Answer 5

ran beside the samples as it contains linear pieces of DNA of known lengths that can be used to compare to sample DNA to determine their size.

Question 6

What is Ethidium bromide dye used for?

Answer 6

indicating the DNA you want to detect

Question 7

Why do we have to visualize the DNA fragments in the gel using UV light?

Answer 7

Ethidium bromide inserts between base pairs in the DNA and fluoresces under UV light. Thus allows us to visualize the DNA fragments.

Question 8

What do bands on the gel constitute?

Answer 8

thousands of microscopic fragments of a given size.