BIO 344 Final Exam Questions and
Correct Verified Answers Rated
A+(2025-2026) Reviewed.
How do proteins get moved between the nucleus and cytosol - Answer Nucleus- Gated
transport
Mitochondria- trans membrane transport
ER- trans membrane transport then to vesicle transport to get to golgi
What are nuclear pore complexes (NPC) - Answer Large structure that perforate the nuclear
envelope and transports macromolecules bidirectionally in ER
What is a nuclear import receptor - Answer initiates nuclear import, cytosolic proteins that
bind the signal on the protein to be transported to the NPC then to cytsol
What molecule delivers energy to facilitate transport of large proteins into the nucleus - Answer
GTPase Ran
Describe the sub compartments of mitochondria and chloroplasts - Answer Mito- inner and
outer space with matrix in center.
Chloroplast- Thylakoid space and stroma in middle
What are protein translocators - Answer mediate protein translocation across mitochondria
TOM- outer membrane
TIM- inner membrane
Why does it matter that the mitochondrial signal sequence for protein import forms an alpha
helix? Describe the properties of this alpha helix - Answer When folded as alpha helix, it is
amphiphillic. One side alpha helix is polar, other side charged
Describe how proteins are imported into mitochondrial matrix - Answer -Cross the membrane
separately or both at once.
-Bind to their signal sequences
, What molecule provides energy for transport of proteins into the mitochondria - Answer ATP
hydrolysis
How do proteins get directed to the membrane space? - Answer -Matrix space has to cross
two different spaces at once
- has to have separate signaling sequence to be transferred to the inter membrane space
What is the difference between smooth ER and rough ER - Answer Smooth- make
phospholipid fatty acids, no ribosomes,
Rough- is rough, Yes ribosomes, where translation and synthesis of proteins occur
Where does protein synthesis start - Answer Protein synthesis begins in the cytosol in free
ribosomes
How does a protein get directed to the ER - Answer The signal sequence binds to the Signal-
Recognition Particle(SRP) which is possible due to the crystal structure of the SRP
protein( accommodates many shapes, sizes and sequences)⇒ SRP binds to ribosome
⇒ribosome binds to ER during the protein synthesis block(ensures protein will not be released
into cytosol)⇒ SRP-ribosome complex binds to SRP Receptor⇒ goes to protein translocator, SRP
and SRP receptor are released ⇒The protein is then pulled by translocator across the
membrane
What is the signal recognition particle and the SRP receptor do - Answer - changes shape
-binds to ER
- recognizes signal squence
What happens to the signal sequence after a protein has passed into the ER - Answer The
signal sequence continues until it is blocked by a stop-signal sequence
How do transmembrane proteins end up in the ER membrane - Answer 3 Ways:
ER signal sequences that have start and stop transfer signals
1. N-terminal signal sequence initiates translocation⇒an additional hydrophobic segment in the
polypeptide chain stops the transfer process⇒ stop transfer signal enters translocator and
anchors the protein in the membrane⇒conformation of translocator changes and discharges
protein laterally into the lipid bilayer
Correct Verified Answers Rated
A+(2025-2026) Reviewed.
How do proteins get moved between the nucleus and cytosol - Answer Nucleus- Gated
transport
Mitochondria- trans membrane transport
ER- trans membrane transport then to vesicle transport to get to golgi
What are nuclear pore complexes (NPC) - Answer Large structure that perforate the nuclear
envelope and transports macromolecules bidirectionally in ER
What is a nuclear import receptor - Answer initiates nuclear import, cytosolic proteins that
bind the signal on the protein to be transported to the NPC then to cytsol
What molecule delivers energy to facilitate transport of large proteins into the nucleus - Answer
GTPase Ran
Describe the sub compartments of mitochondria and chloroplasts - Answer Mito- inner and
outer space with matrix in center.
Chloroplast- Thylakoid space and stroma in middle
What are protein translocators - Answer mediate protein translocation across mitochondria
TOM- outer membrane
TIM- inner membrane
Why does it matter that the mitochondrial signal sequence for protein import forms an alpha
helix? Describe the properties of this alpha helix - Answer When folded as alpha helix, it is
amphiphillic. One side alpha helix is polar, other side charged
Describe how proteins are imported into mitochondrial matrix - Answer -Cross the membrane
separately or both at once.
-Bind to their signal sequences
, What molecule provides energy for transport of proteins into the mitochondria - Answer ATP
hydrolysis
How do proteins get directed to the membrane space? - Answer -Matrix space has to cross
two different spaces at once
- has to have separate signaling sequence to be transferred to the inter membrane space
What is the difference between smooth ER and rough ER - Answer Smooth- make
phospholipid fatty acids, no ribosomes,
Rough- is rough, Yes ribosomes, where translation and synthesis of proteins occur
Where does protein synthesis start - Answer Protein synthesis begins in the cytosol in free
ribosomes
How does a protein get directed to the ER - Answer The signal sequence binds to the Signal-
Recognition Particle(SRP) which is possible due to the crystal structure of the SRP
protein( accommodates many shapes, sizes and sequences)⇒ SRP binds to ribosome
⇒ribosome binds to ER during the protein synthesis block(ensures protein will not be released
into cytosol)⇒ SRP-ribosome complex binds to SRP Receptor⇒ goes to protein translocator, SRP
and SRP receptor are released ⇒The protein is then pulled by translocator across the
membrane
What is the signal recognition particle and the SRP receptor do - Answer - changes shape
-binds to ER
- recognizes signal squence
What happens to the signal sequence after a protein has passed into the ER - Answer The
signal sequence continues until it is blocked by a stop-signal sequence
How do transmembrane proteins end up in the ER membrane - Answer 3 Ways:
ER signal sequences that have start and stop transfer signals
1. N-terminal signal sequence initiates translocation⇒an additional hydrophobic segment in the
polypeptide chain stops the transfer process⇒ stop transfer signal enters translocator and
anchors the protein in the membrane⇒conformation of translocator changes and discharges
protein laterally into the lipid bilayer
