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Molecular Cell Biology Chapter 11
Questions and Correct Answers
Sorting and targeting of proteins to appropriate destinations are important
tasks for?
Ans✅✅: eukaryotic cells
These structures are associated with protein processing and connected by
vesicular transport
Ans✅✅: Endoplasmic reticulum, Golgi apparatus, endosomes, lysosomes
Network of membrane-enclosed tubules and sacs (cistern)- extends from
nuclear membrane throughout cytoplasm
Ans✅✅: Endoplasmic reticulum (ER)
Has ribosomes on the outer surface
Ans✅✅: Rough ER
Is responsible for lipid metabolism
Ans✅✅: Smooth ER
Newly synthesized proteins were labeled with?
Ans✅✅: radioisotopes
After labeling, incubation with non-labeled amino acids for different lengths of
time allowed them to track the labeled proteins through the?
Ans✅✅: ER, Golgi apparatus, secretory vesicles, and then outside the
cell
Pretest - Stuvia US
,2
These experiments defined the ______. Rough Er-> Gogl->secretary vesicles-
> cell exterior. Further studies showed a similar pathway for non-secreted
proteins.
Ans✅✅: secretory pathway
In eukaryotic cells, initial sorting takes place while _____ is in progress.
Ans✅✅: translation
Proteins synthesized on _____ stay in the cytosol or are transported to the
nucleus and other organelles
Ans✅✅: free ribosomes
Proteins synthesized on ____ are translocated directly into the ER.
Ans✅✅: membrane-bound ribosomes
on membrane-bound ribosomes
Ans✅✅: cotranslational translocation
on ribosomes that are free in the cytosol
Ans✅✅: Posttranslational translocation
Targeted to the ER by a signal sequence
Ans✅✅: cotranslational pathway
When cells are disrupted and the nuclei centrifuged out, the ER breaks up into
small vesicles called?
Ans✅✅: microsomes
These two scientist found that translation of secretory proteins on free
ribosomes retained the signal sequences and were slightly larger in 1975
Pretest - Stuvia US
, 3
Ans✅✅: Blobel and Sabatini
When microsomes were added, the signal sequences were removed by?
Ans✅✅: proteolytic cleavage
Signal sequences (about 20 amino acids) include a stretch of ______, and are
usually located at the amino terminus of the polypeptide chain
Ans✅✅: hydrophobic residues
Cotranslational targeting bound by a?
Ans✅✅: signal recognition particle (SRP)
SRPs consist of ____ polypeptides and a small cytoplasmic RNA
Ans✅✅: 6
The SRP binds the ribosome and the signal sequence, inhibiting further?
Ans✅✅: translation
The entire complex binds to a ____ on the rough ER membrane
Ans✅✅: SRP receptor
The SRP is then released, and the ribosome binds to a membrane channel or?
Ans✅✅: translocon
The signal sequence is inserted into the translocon, and?
Ans✅✅: translation resumes
The signal sequence is cleaved by _____ and released into the ER lumen
Ans✅✅: signal peptidase
Pretest - Stuvia US
Molecular Cell Biology Chapter 11
Questions and Correct Answers
Sorting and targeting of proteins to appropriate destinations are important
tasks for?
Ans✅✅: eukaryotic cells
These structures are associated with protein processing and connected by
vesicular transport
Ans✅✅: Endoplasmic reticulum, Golgi apparatus, endosomes, lysosomes
Network of membrane-enclosed tubules and sacs (cistern)- extends from
nuclear membrane throughout cytoplasm
Ans✅✅: Endoplasmic reticulum (ER)
Has ribosomes on the outer surface
Ans✅✅: Rough ER
Is responsible for lipid metabolism
Ans✅✅: Smooth ER
Newly synthesized proteins were labeled with?
Ans✅✅: radioisotopes
After labeling, incubation with non-labeled amino acids for different lengths of
time allowed them to track the labeled proteins through the?
Ans✅✅: ER, Golgi apparatus, secretory vesicles, and then outside the
cell
Pretest - Stuvia US
,2
These experiments defined the ______. Rough Er-> Gogl->secretary vesicles-
> cell exterior. Further studies showed a similar pathway for non-secreted
proteins.
Ans✅✅: secretory pathway
In eukaryotic cells, initial sorting takes place while _____ is in progress.
Ans✅✅: translation
Proteins synthesized on _____ stay in the cytosol or are transported to the
nucleus and other organelles
Ans✅✅: free ribosomes
Proteins synthesized on ____ are translocated directly into the ER.
Ans✅✅: membrane-bound ribosomes
on membrane-bound ribosomes
Ans✅✅: cotranslational translocation
on ribosomes that are free in the cytosol
Ans✅✅: Posttranslational translocation
Targeted to the ER by a signal sequence
Ans✅✅: cotranslational pathway
When cells are disrupted and the nuclei centrifuged out, the ER breaks up into
small vesicles called?
Ans✅✅: microsomes
These two scientist found that translation of secretory proteins on free
ribosomes retained the signal sequences and were slightly larger in 1975
Pretest - Stuvia US
, 3
Ans✅✅: Blobel and Sabatini
When microsomes were added, the signal sequences were removed by?
Ans✅✅: proteolytic cleavage
Signal sequences (about 20 amino acids) include a stretch of ______, and are
usually located at the amino terminus of the polypeptide chain
Ans✅✅: hydrophobic residues
Cotranslational targeting bound by a?
Ans✅✅: signal recognition particle (SRP)
SRPs consist of ____ polypeptides and a small cytoplasmic RNA
Ans✅✅: 6
The SRP binds the ribosome and the signal sequence, inhibiting further?
Ans✅✅: translation
The entire complex binds to a ____ on the rough ER membrane
Ans✅✅: SRP receptor
The SRP is then released, and the ribosome binds to a membrane channel or?
Ans✅✅: translocon
The signal sequence is inserted into the translocon, and?
Ans✅✅: translation resumes
The signal sequence is cleaved by _____ and released into the ER lumen
Ans✅✅: signal peptidase
Pretest - Stuvia US
