Cell 201 - Midterm 3
Comprehensive Questions
with Verified Answers
Graded A+
1. endomembrane system includes Answer: nuclear envelope, endoplasmic reticulum
(ER), Golgi apparatus, lysosomes, endosomes, vesicles, vacuoles, and plasma membrane
-Connected directly or indirectly through vesicle transport.Ves
2. What is vesicular transport? Answer: Most proteins and lipids are transcribed and
incorporated into mem- branes in the ER. From there, they are transported to their destinations.
This process includes endocytosis and exocytosis, anterograde transport and retrograde transport,
and transition vesicles and secretory vesicles.
3. What is anterograde transport? Answer: movement of materials towards plasma
membrane (away from ER)
4. How do vesicles get recycled in a cell? Answer: In anterograde transport, when
vesicles made of ER membrane travel all the way to the plasma membrane, the membrane from ER
becomes part of the plasma membrane after exocytosis. The reverse occurs in retrograde transport.
,5. What is retrograde transport? Answer: Retrograde transport is the flow of vesicles
from the PM and other compartments back to the ER
6. Why is vesicular transport important to the cell? Answer: critical for
balancing the flow of lipids and membrane proteins toward the plasma membrane and
tinuous network
maintaining ORGANELLE IDENTITY. of
7. What is the Endoplasmic Reticulum? Answer: The endoplasmicnd sacs are
reticulum (ER) is a con flattened sacs, tubules, and vesicles through the cytoplasm
of a eukaryotic cell. The membrane-bou ER cisternae and the space inside them is the
ER lumen.
8. ER cisternae Answer: membrane bound sacs in ER
9. ER lumen Answer: The area enclosed by the ER membrane.
10. What are the 2 types of ER? Answer: 1. Rough ER
2. Smooth ER
11. How do the 2 types of ER differ in structure and function?
Answer: 1) Rough endoplasmic reticulum (rough ER) is where proteins are inserted into the
ER. Has many Sec61 translocon complexes with ribosomes
,on the cytosolic side of the membrane.
2) Smooth ER lacks ribosomes but is a major site of membrane and lipid biosynthesis.
12. What is the Translational ER (tER) Answer: Transitional ER (tER) is located at the
edge of the rough ER and plays a role in the formation of vesicles that shuttle lipids and proteins
from the ER to the Golgi complex. Kickstarts the process of anterograde transport.
13. How do you distinguish b/w Rough ER and Smooth ER? Answer: -
Rough ER ---> forms large flattened sheets (can see the tiny dots on the sheets which are
bound ribosomes).
-Smooth ER ---> forms tubular structures.
14. What is the relative variation in amounts of Rough ER to
Smooth ER ratio present in cells? Answer: - Cells involved in synthesis of secretory
proteins have prominent rough ER networks (b/c bound ribosomes synthesize proteins destined
for secretion).
-Cells producing steroid hormones tend to have extensive networks of smooth ER (b/c lipids are made
in the Smooth ER).
15. How does Rough ER synthesize and process proteins? Answer: -
Cells producing steroid hormones tend to have extensive networks of smooth ER.
-Folding of secreted and membrane proteins (chaperones, PDI, etc).
-Addition of carbohydrates to glycoproteins (not shown) (glycosylation enzymes, etc).
-recognition and removal of misfolded proteins (chaperones, etc).
-Assembly and budding of vesicles for transport to other compartments or secretion.
16. How does the Translational ER package proteins into transport
, vesicles?-
Answer: Assembly and budding of vesicles for transport to other compartments or secretion (Sec12,
Sar1, COPII proteins (Sec13/31, Sec23/24)).
17. What does the Smooth ER do? Answer: 1) drug detoxification
2) carbohydrate metabolism
3) calcium storage (Ca2+ ions)
4) steroid biosynthesis (fats/lipids)
18. How does the smooth ER detoxify drugs? Answer: 1) Drug detoxification
often involves hydroxylation Answer: adding hydroxyl groups to a drug increases solubility,
making them easier to excrete from the body.
2) Enzymes involved in this process can be upregulated and smooth ER can proliferate due to drug
exposure.
19. proliferate Answer: to reproduce, increase, or spread rapidly
Comprehensive Questions
with Verified Answers
Graded A+
1. endomembrane system includes Answer: nuclear envelope, endoplasmic reticulum
(ER), Golgi apparatus, lysosomes, endosomes, vesicles, vacuoles, and plasma membrane
-Connected directly or indirectly through vesicle transport.Ves
2. What is vesicular transport? Answer: Most proteins and lipids are transcribed and
incorporated into mem- branes in the ER. From there, they are transported to their destinations.
This process includes endocytosis and exocytosis, anterograde transport and retrograde transport,
and transition vesicles and secretory vesicles.
3. What is anterograde transport? Answer: movement of materials towards plasma
membrane (away from ER)
4. How do vesicles get recycled in a cell? Answer: In anterograde transport, when
vesicles made of ER membrane travel all the way to the plasma membrane, the membrane from ER
becomes part of the plasma membrane after exocytosis. The reverse occurs in retrograde transport.
,5. What is retrograde transport? Answer: Retrograde transport is the flow of vesicles
from the PM and other compartments back to the ER
6. Why is vesicular transport important to the cell? Answer: critical for
balancing the flow of lipids and membrane proteins toward the plasma membrane and
tinuous network
maintaining ORGANELLE IDENTITY. of
7. What is the Endoplasmic Reticulum? Answer: The endoplasmicnd sacs are
reticulum (ER) is a con flattened sacs, tubules, and vesicles through the cytoplasm
of a eukaryotic cell. The membrane-bou ER cisternae and the space inside them is the
ER lumen.
8. ER cisternae Answer: membrane bound sacs in ER
9. ER lumen Answer: The area enclosed by the ER membrane.
10. What are the 2 types of ER? Answer: 1. Rough ER
2. Smooth ER
11. How do the 2 types of ER differ in structure and function?
Answer: 1) Rough endoplasmic reticulum (rough ER) is where proteins are inserted into the
ER. Has many Sec61 translocon complexes with ribosomes
,on the cytosolic side of the membrane.
2) Smooth ER lacks ribosomes but is a major site of membrane and lipid biosynthesis.
12. What is the Translational ER (tER) Answer: Transitional ER (tER) is located at the
edge of the rough ER and plays a role in the formation of vesicles that shuttle lipids and proteins
from the ER to the Golgi complex. Kickstarts the process of anterograde transport.
13. How do you distinguish b/w Rough ER and Smooth ER? Answer: -
Rough ER ---> forms large flattened sheets (can see the tiny dots on the sheets which are
bound ribosomes).
-Smooth ER ---> forms tubular structures.
14. What is the relative variation in amounts of Rough ER to
Smooth ER ratio present in cells? Answer: - Cells involved in synthesis of secretory
proteins have prominent rough ER networks (b/c bound ribosomes synthesize proteins destined
for secretion).
-Cells producing steroid hormones tend to have extensive networks of smooth ER (b/c lipids are made
in the Smooth ER).
15. How does Rough ER synthesize and process proteins? Answer: -
Cells producing steroid hormones tend to have extensive networks of smooth ER.
-Folding of secreted and membrane proteins (chaperones, PDI, etc).
-Addition of carbohydrates to glycoproteins (not shown) (glycosylation enzymes, etc).
-recognition and removal of misfolded proteins (chaperones, etc).
-Assembly and budding of vesicles for transport to other compartments or secretion.
16. How does the Translational ER package proteins into transport
, vesicles?-
Answer: Assembly and budding of vesicles for transport to other compartments or secretion (Sec12,
Sar1, COPII proteins (Sec13/31, Sec23/24)).
17. What does the Smooth ER do? Answer: 1) drug detoxification
2) carbohydrate metabolism
3) calcium storage (Ca2+ ions)
4) steroid biosynthesis (fats/lipids)
18. How does the smooth ER detoxify drugs? Answer: 1) Drug detoxification
often involves hydroxylation Answer: adding hydroxyl groups to a drug increases solubility,
making them easier to excrete from the body.
2) Enzymes involved in this process can be upregulated and smooth ER can proliferate due to drug
exposure.
19. proliferate Answer: to reproduce, increase, or spread rapidly
