Cell Bio Final_Exam 2_2019

Question 1

1. What accounts for the differences in function between the types of ER?
   1) The location of the ER
   2) The proximity of the ER to the nucleus
   3) The protein content of the ER
   4) The shape of its component lipids

Answer 1

C: 3

Question 2

2. Which of the following is NOT a function associated with the smooth endoplasmic reticulum in at least some cells?
   A. Synthesis of steroid hormones
   B. Detoxification of many organic compounds, like barbiturates and ethanol
   C. Synthesis of some kind of lipid
   D. Synthesis of integral protein
   E. Sequestration of calcium Ca2+ ions within the cisternal space

Answer 2

D: Synthesis of integral protein

Question 3

3. What is the arrangement of organelles in a secretory cell from the basal end to the apical end, an arrangement that reflects the flow of secretory products from synthesis to discharge?
   A. Golgi complex- nucleus and RER- secretory vesicles
   B. Nucleus and RER- Golgi complex- secretory vesicles
   C. Nucleus and RER- secretory vesicles- nucleus and RER
   D. Golgi complex- secretory vesicles- nucleus and RER
   E. Secretory vesicles- nucleus and RER- Golgi complex

Answer 3

B: Nucleus and RER- Golgi complex- secretory vesicles

Question 4

4. What are the two sites within a cell at which protein synthesis is generally thought to occur?
   A. Cytosolic surface of RER and cisternal surface of RER
   B. Cytosolic surface of RER and free ribosomes
   C. Cisternal surface of RER and free ribosomes
   D. Free ribosomes and cytosolic surface of RER
   E. Cytosolic surface of RER and cytosolic surface of SER

Answer 4

B: Cytosolic surface of RER and free ribosomes

Question 5

5. Blobel, Sabatini, and Dobberstein proposed that the site of protein synthesis is determined by information contained in the N-terminal portion of the protein, the first part to emerge from the ribosome. What did they call their proposal?

Answer 5

D: The signal hypothesis

Question 6

6.	What effect does the binding of SRP to the growing polypeptide chain and the ribosome have on protein synthesis?
A.	Protein synthesis accelerates 
B.	Protein synthesis ceases temporarily 
C.	Protein synthesis ceases permanently
D.	Protein synthesis is terminated
E.	The ribosome dissociates

Answer 6

B: Protein synthesis ceases temporarily

Question 7

7. Why is the ER so well-suited and ideally constructed for its role as a port of entry for secretory proteins?
   1) It has a large surface area allowing the attachment of many ribosomes.
   2) The ER cisternae lumen favors folding and assembly of proteins.
   3) The RER can segregate secretory, lysosomal and cytoplasmic proteins from other newly made proteins, allowing their modification, and sends them to their final destination

Answer 7

D: 1 and 2

Question 8

8. How are integral membrane proteins thought to enter the lipid bilayer?
   A. They insert into the membrane from the RER lumen after their synthesis is complete.
   B. The aqueous translocon channel seems to have a gate that continuously opens and closes, giving each nascent polypeptide segment a chance to partition itself into the lipid bilayer’s hydrophobic core.
   C. They insert into the membrane from the cytosol after their synthesis is complete.
   D. It is thought that they burrow into the lipid bilayer.
   E. It is thought that they are enzymatically implanted in the lipid bilayer.

Answer 8

B: The aqueous translocon channel seems to have a gate that continuously opens and closes, giving each nascent polypeptide segment a chance to partition itself into the lipid bilayer’s hydrophobic core.

Question 9

9. How and where is the asymmetry of the phospholipid bilayers initially established?
   A. It is initially established in the Golgi complex during lipid and protein modification
   B. It is initially established in the ER during lipid and protein synthesis
   C. It is initially established in the secretory vesicles during lipid and protein modification
   D. It is initially established in the mitochondria by random insertion into the membranes
   E. All of these are correct

Answer 9

B: It is initially established in the ER during lipid and protein synthesis

Question 10

10.	To what residue of a polypeptide are N-linked oligosaccharide chains attached as that polypeptide enters the RER lumen through the translocon? 
A.	Arginine
B.	Asparagine
C.	Serine
D.	Threonine
E.	Ninhydrin

Answer 10

B: Asparagine

Question 11

11. How do protein coats select the cargo molecules to be carried by the vesicles they help to form?
    A. They electromagnetically attract the correct cargo proteins
    B. The protein coats have a specific affinity for the cytosolic tails of integral membrane proteins that reside in the donor membrane
    C. The coats have a specific affinity for the luminal tails of integral membrane proteins that reside in the donor membrane
    D. The coat proteins directly attach to the cargo proteins in the lumen of the forming vesicles
    E. The coat proteins attach to the extracellular matrix

Answer 11

B: The protein coats have a specific affinity for the cytosolic tails of integral membrane proteins that reside in the donor membrane

Question 12

12. The coat vesicles that transport materials around the cell interior __________.
    1) Is composed of two distinct protein layers
    2) Possesses an outer cage or scaffolding that forms the framework for the coat
    3) Possesses adaptors that are able to select specific cargo molecules
    4) Possesses an inner layer of adaptors that serves primarily to bind the vesicle’s cargo
    A. 1 + 2 + 4
    B. 2 + 3 + 4
    C. 1 + 3 + 4
    D. 1 + 2 + 3
    E. 1 + 2 + 3 + 4

Answer 12

E: 1 + 2 + 3 + 4

Question 13

13.	What would happen to the movement of vesicles toward their eventual target if a microtubule inhibitor, which can prevent assembly of the microtubule, were added to the cells?
A.	The vesicles would disintegrate
B.	The vesicles would move faster
C.	Vesicle movement would slow or stop
D.	Vesicles will shrink
E.	Vesicles will swell

Answer 13

C: Vesicle movement would slow or stop

Question 14

14.	Which of the following enzymes are typically found in lysosomes?
A.	Hydrolytic enzyme (acid hydrolases)
B.	Oxidoreductases
C.	Transferases
D.	Lyases
E.	Ligases

Answer 14

A: Hydrolytic enzyme (acid hydrolases)

Question 15

15. What is thought to shield lysosomal membranes against attack by their enclosed enzymes?
    A. DNA
    B. Basic RNA
    C. Carbohydrate chains attached to integral membrane proteins
    D. Carbohydrate chains attached to peripheral membrane proteins
    E. The lipid bilayer itself

Answer 15

C: Carbohydrate chains attached to integral membrane proteins

Question 16

16.	What process is responsible for organelle turnover in the cell and carious out the regulated destruction of the cell’s own organelles for the purpose of recycling the components of which they are made? 
A.	Autolysis
B.	Autophagolysosome
C.	Apoptosis
D.	Autophagy
E.	Autonomy

Answer 16

D: Autophagy

Question 17

17.	The two separate (basic) categories of uptake of extracellular materials into cytoplasmic vesicles are \_\_\_\_\_ and \_\_\_\_\_\_\_. 
A.	Phagocytosis, exocytosis
B.	Pinocytosis, exocytosis
C.	Phagocytosis, endocytosis
D.	Pinocytosis, endocytosis
E.	Exocytosis, endocytosis

Answer 17

C: Phagocytosis, endocytosis

Question 18

18. What types of molecules below can a cell internalize by receptor-mediated endocytosis?
    A. Hormones and growth factors
    B. Enzymes
    C. Bloode-borne proteins carrying certain nutrients
    D. Hormones and growth factors and enzymes
    E. All of these are correct

Answer 18

E: All of these are correct

Question 19

19.	Which of the following organelle does not belong to the endomembrane system? 
A.	Endoplasmic reticulum
B.	Golgi complex
C.	Endosomes
D.	Lysosomes
E.	Mitochondria

Answer 19

E: Mitochondria

Question 20

20.	The microtubule wall is composed of globular proteins arranged in longitudinal rows called \_\_\_\_\_\_\_.
A.	Microfilaments
B.	Protofilaments
C.	Protubules
D.	Protubulins
E.	Microtubular units

Answer 20

B: Protofilaments

Question 21

21.	Initiation site for microtubule nucleation is: 
A.	Centrosome
B.	Centriole
C.	Pericentriolar materials (PCM)
D.	A tubule
E.	B tubule

Answer 21

C: Pericentriolar materials (PCM)

Question 22

22.	Which type of cytoskeletal element is described as tough, ropelike fibers composed of a variety of related proteins like keratin?
A.	Microfilaments
B.	Microtubules
C.	Intermediate filaments
D.	Macrofilaments
E.	Indeterminate filaments

Answer 22

C: Intermediate filaments

Question 23

23. Which of the following is a function performed by the cytoskeleton?
    A. Provides structural support that determines cell shape and resists deforming faces
    B. Positions various organelles within the cell interior
    C. Provides a network of tracks over which materials like mRNA and organelles move within cells
    D. Serves as a force-generating apparatus that moves cells from one place to another
    E. All of these choices

Answer 23

E: All of these choices

Question 24

24.	What is the direct source of energy that powers molecular motors?
A.	Hydrolysis of GTP 
B.	Hydrolysis of ATP
C.	A proton gradient
D.	A H+ gradient
E.	Condensation of ATP

Answer 24

B: Hydrolysis of ATP

Question 25

25. The current model for the nucleation of microtubules is that a helical array of y-tubulin subunits forms an open, lock-washer-like-ring-shaped template upon which the first row of αβ-tubulin dimers assembles. How does this model account for the polarity of microtubulues?
    A. Only the α-tubulin of a heterodimer can bind to the ring of y-subunits
    B. Only the β-tubulin of a heterodimer can bind to the ring od y-subunits
    C. The ring structure straightens out the microtubule
    D. The ring structure interacts with a homodimer instead of a heterodimer.
    E. Only the β-tubulin of a heterodimer can bind to the ring of y-subunits and the ring structure straightens out the mictrotubule

Answer 25

A: Only the α-tubulin of a heterodimer can bind to the ring of y-subunits

Question 26

26.	Which MTOC gives rise to cilia and flagella?
A.	A centrosome
B.	Basal surface
C.	Centriole
D.	PCM
E.	The plus end

Answer 26

B: Basal surface

Question 27

27.	To which end of microtubulues are tubulin subunits primarily added in vitro?
A.	The minus end
B.	The N-terminal end
C.	The plus end
D.	The C-terminal end
E.	The 5’-end

Answer 27

C: The plus end

Question 28

28. With which of the following structures are intermediate filaments associated?
    A. The nuclear envelope in the center of the cell
    B. Hemidesmosomes
    C. Desmosomes
    D. The neurofilaments of neuron axons
    E. All of these choices

Answer 28

B: All of these choices

Question 29

29. Which of the following description of assembly of microfilament in vitro is (are) correct?
    1) ATP-bound actin monomer is the building block for microfilaments
    2) Nucleation of microfilament in vitro requires performed microfilament as a seed
    3) Assemble of microfilaments have polarity, i.e., fast-growth end and slow-growing end
    4) When reach steady state, length of microfilament and free ATP-actin remain constant

Answer 29

E: 1 + 2 + 3 + 4

Question 30

30. What kinds of forces are thought to hold microtubular structure together?
    A. Strong interactions
    B. Noncovalent interactions
    C. Covalent interactions
    D. Magnetism
    E. Strong interactions and covalent interactions

Answer 30

B: Noncovalent interactions