---

Question 1:

What is the principle behind electrophoresis?

A) Diffusion of particles in a liquid medium
B) Separation based on molecular weight
C) Movement of charged particles in an electric field
D) Interaction between antigens and antibodies

Show Answer

Explanation: The correct answer is C) Movement of charged particles in an electric field. The principle behind electrophoresis is the migration of charged particles (such as proteins or nucleic acids) in an electric field. The particles move towards the electrode with the opposite charge, allowing for their separation based on size, charge, or other factors.

---

Question 2:

Which of the following techniques is used to separate DNA fragments based on size using electrophoresis?

A) Gel electrophoresis
B) Capillary electrophoresis
C) Isoelectric focusing
D) Two-dimensional electrophoresis

Show Answer

Explanation: The correct answer is A) Gel electrophoresis. Gel electrophoresis is a commonly used technique in molecular biology to separate DNA fragments based on size. DNA samples are loaded onto a gel matrix and subjected to an electric field, causing the fragments to migrate through the gel. Smaller fragments move faster and travel farther, resulting in separation based on size.

---

Question 3:

Which electrophoretic technique is used to separate proteins based on their isoelectric point?

A) Gel electrophoresis
B) Capillary electrophoresis
C) Isoelectric focusing
D) Two-dimensional electrophoresis

Show Answer

Explanation: The correct answer is C) Isoelectric focusing. Isoelectric focusing is an electrophoretic technique used to separate proteins based on their isoelectric point (pI), which is the pH at which a protein has no net charge. In isoelectric focusing, a pH gradient is established in a gel or a capillary, and proteins migrate until they reach their respective pI values, resulting in separation based on charge.

---

Question 4:

Which electrophoretic technique is commonly used for DNA sequencing?

A) Gel electrophoresis
B) Capillary electrophoresis
C) Isoelectric focusing
D) Two-dimensional electrophoresis

Show Answer

Explanation: The correct answer is B) Capillary electrophoresis. Capillary electrophoresis is commonly used for DNA sequencing. In this technique, DNA fragments are separated in a narrow capillary filled with a polymer matrix. The fragments migrate through the capillary under the influence of an electric field, and the separation is detected by fluorescence-based methods, allowing for the determination of the DNA sequence.

---

Question 5:

What is the purpose of loading a molecular weight marker in electrophoresis?

A) To estimate the amount of DNA or protein in the sample
B) To determine the separation efficiency of the gel
C) To identify specific proteins or DNA fragments
D) To determine the molecular weight of the sample components

Show Answer

Explanation: The correct answer is D) To determine the molecular weight of the sample components. Loading a molecular weight marker in electrophoresis helps in determining the molecular weight of the sample components. The marker contains known-sized fragments of DNA or proteins with known molecular weights. By comparing the migration of the sample bands with the marker bands, the approximate molecular weight of the sample components can be estimated.