OAT Cell and Molecular Biology 4

Question 1

Which protein complex coats COPII vesicles that transport cargo from the ER to the Golgi?

Accepted Answer

Sec23/Sec24 and Sec13/Sec31

Answer

COPII vesicles are coated by the Sec23/Sec24 inner layer and Sec13/Sec31 outer cage, driven by the small GTPase Sar1.

Question 2

Which checkpoint ensures that all chromosomes are properly attached to the spindle before anaphase onset?

Accepted Answer

Spindle assembly checkpoint (SAC)

Answer

The SAC monitors kinetochore-microtubule attachment and inhibits the APC/C via the mitotic checkpoint complex until all chromosomes are bi-oriented.

Question 3

In the lac operon, cAMP-CAP binding to the promoter is required when:

Accepted Answer

Lactose is present and glucose is absent

Answer

Low glucose causes cAMP to accumulate; cAMP-CAP binding to the lac promoter is needed for maximal transcription when lactose is the carbon source.

Question 4

What is the function of telomerase reverse transcriptase (TERT)?

Accepted Answer

It synthesizes telomeric repeats using an RNA template it carries

Answer

Telomerase uses its built-in RNA component (TERC) as a template to extend the 3' G-rich overhang of linear chromosomes.

Question 5

Which protein anchors the actin cytoskeleton to the plasma membrane at focal adhesions?

Accepted Answer

Talin

Answer

Talin links integrin cytoplasmic tails to actin filaments, forming a critical mechanical bridge at focal adhesion complexes.

OAT - Optometry Admission Test Practice Test