Question

During cellular fractionation, which organelle typically forms part of the pellet when centrifuged at 1000g for 10 minutes?

• A. Ribosomes
• B. Nucleus
• C. Endoplasmic Reticulum
• D. Lysosomes

Hint:

In differential centrifugation:
{Low speed → Large organelles (Nucleus)}
{Higher speed → Smaller organelles}.

Answer 1

The Correct Option is B

Concept: Cellular fractionation is a laboratory technique used to separate cellular components based on their size and density using differential centrifugation. During centrifugation, heavier and larger organelles sediment faster and form pellets at lower centrifugal speeds.
Step 1:Principle of differential centrifugation.
When a homogenized cell extract is centrifuged at increasing speeds, organelles sediment in the order of their size and density. Larger organelles pellet first, while smaller components remain in the supernatant.
Step 2:Low-speed centrifugation.
At approximately (1000g) for about 10 minutes, the largest and heaviest cellular structures sediment. These typically include: [ \text{Nuclei, unbroken cells, and large cell debris} ]
Step 3:Subsequent centrifugation steps.
Higher centrifugal forces are required to pellet smaller organelles:

• (10,000g): mitochondria and lysosomes
• (100,000g): microsomes and fragments of endoplasmic reticulum
• (>100,000g): ribosomes

Thus, during centrifugation at (1000g) for 10 minutes, the organelle that forms part of the pellet is the nucleus.