MCQs on Gel electrophoresis, Oligonucleotide & Microarrays – 1
1 - Question
Gel electrophoresis separates nucleic acid molecules based on ____________
a) charge on molecules
b) size of the molecules
c) nature of the molecules i.e. whether DNA or RNA
d) chemical properties of the nucleic acids
Explanation: Gel electrophoresis separates nucleic acid molecules on the basis of their size. The nucleic acid molecules move through the gel because of the force provided by the applied electric field.
2 - Question
The charge present on the DNA backbone is negative. The force required to accelerate the molecules towards anode is directly proportional to the number of ____________
a) sugar molecules
b) nitrogenous bases
c) phosphate groups
d) both phosphate group and sugar molecules
Explanation: The DNA backbone is negatively charged because of the phosphate groups. Hence, the force required to move the molecules towards anode is directly proportional to the number of phosphate groups present.
3 - Question
Force is defined as mass per unit acceleration. As the number of phosphate molecules increases, the charge also increases which increases the force required. The acceleration is dependent on the size of the molecules.
Explanation: As the charge increases, which is because of the number of phosphate molecules, the size also increases. As, the size increases, it also results in increase of mass. Thus, now the force and also the acceleration are independent of size until a retarding force is present. But, in the case of gel electrophoresis, the retarding force is provided by gel and thus separation takes place on the basis of size.
4 - Question
Which one of the following will travel fastest through the gel if the amount of DNA present is same in all?
d) Supercoiled and circular will move at same speed and faster than nicked
Explanation: The supercoiled form of DNA will travel the fastest. It is so because; the movement through the gel is based on the size. The smaller the molecule is the less retarding force it experiences when it moves. Hence, supercoiled which is having the smallest size will move the fastest. advertisement