Question 1

Which principle allows differential centrifugation to separate cellular organelles?

Accepted Answer

Organelles are separated based on their density and size.

Question 2

During differential centrifugation, which organelle is most likely to pellet first at low speed?

Accepted Answer

Nuclei

Question 3

What is the role of the nuclear localization signal (NLS) in protein transport?

Accepted Answer

It directs proteins to enter the nucleus through the nuclear pore complex.

Question 4

A protein is synthesized in the cytosol and contains an NLS. What is its most likely destination?

Accepted Answer

It will be transported into the nucleus.

Question 5

Which of the following best describes the 'lock and key' model of enzyme-substrate interaction?

Accepted Answer

The enzyme and substrate have complementary shapes and chemical properties.

Question 6

What is the main function of the Golgi apparatus in the endomembrane system?

Accepted Answer

Sorting and modifying proteins for their final destinations

Question 7

Which process is responsible for the formation of vesicles that transport proteins from the Golgi to other cellular locations?

Accepted Answer

Pinching off of the Golgi membrane by receptor clustering

Question 8

A protein with an ER signal sequence is most likely to be synthesized by:

Accepted Answer

Ribosomes bound to the rough endoplasmic reticulum

Question 9

Which of the following is NOT a function of the cytoskeleton?

Accepted Answer

Synthesizing DNA

Question 10

Which motor protein is responsible for moving vesicles along microtubules toward the cell periphery?

Accepted Answer

Kinesin

Question 11

What is the primary difference between phagocytosis and receptor-mediated endocytosis?

Accepted Answer

Phagocytosis engulfs large particles or cells, while receptor-mediated endocytosis is specific for molecules bound to cell surface receptors.

Question 12

Which equation best represents the relationship between force, mass, and acceleration in the context of centrifugation?

Accepted Answer

$$F = m 	imes a$$

Question 13

A protein is found in the nucleus after an NLS is added to its sequence. What does this experiment demonstrate?

Accepted Answer

The NLS is sufficient to direct nuclear import of proteins.

Question 14

Which of the following statements about protein sorting in the cell is correct?

Accepted Answer

Proteins are sorted by specific amino acid tags that are recognized by receptors in the Golgi apparatus.

Question 15

Which cytoskeletal filament is primarily involved in muscle contraction?

Accepted Answer

Actin filaments

Question 16

What is the function of shuttle proteins in nuclear transport?

Accepted Answer

They bind to NLS sequences and facilitate passage through the nuclear pore complex.

Question 17

Which process describes the recycling of worn-out organelles in the lysosome?

Accepted Answer

Autophagy

Question 18

Which of the following is true regarding the synthesis location of proteins destined for secretion?

Accepted Answer

They are synthesized by ribosomes bound to the rough endoplasmic reticulum.

Question 19

Which of the following is NOT a modification that can occur in the Golgi apparatus?

Accepted Answer

Addition of NLS to proteins

Question 20

Which cytoskeletal motor protein is responsible for the movement of cilia and flagella?

Accepted Answer

Dynein

Cellular Processes: Protein Activity, Nuclear Transport, Endomembrane System, and Cytoskeleton

Study Guide - Practice Questions