Bio 344 NAU Final Exam 2 Questions
and All Correct Answers (2025-2026)
Updated.
How do proteins get moved between the nucleus and the cytosol? - Answer By nuclear pore
complex. Small molecules can move across the pores via gated transport. Large molecules are
shuttled across via active transport. Nuclear import receptors bind to nuclear signal sequence.
RAN-GTP provides energy for active transport, but smaller protein will freely diffuse.
What are nuclear pore complexes? - Answer Proteins that actively transport proteins out of
the nucleus.
What is a nuclear import receptor? - Answer Soluble cytoplasmic receptors that direct
molecules to the appropriate nuclear pore complex.
What molecule delivers energy to facilitate transport of large proteins into the nucleus? What
protein is it attached to? - Answer RAN-GTP. Attached to nuclear import receptor.
Describe the subcompartments of mitochondria. - Answer Outer membrane, inner
membrane, intermembrane space, matrix.
-DNA replication occurs.
-ATP synthesis --> proton motive force.
-ATP synthase is inside the inner membrane
-Protons accumulate inside the inner membrane space and move across the inner membrane to
the matrix (ADP --> ATP)
What are protein translocators? - Answer Membrane bound proteins that mediate the
transport of another protein across an organelle membrane.
-TOM --> across outer membrane to inner membrane
-TIM --> across the inner membrane to matrix
Why does it matter that the mitochondrial signal sequence for protein import forms an alpha
helix? Describe the properties of this alpha helix. - Answer One side of the alpha helix is polar
and is recognized by receptor proteins on mitochondria.
, membranes. The signal sequence is then cleaved by a signal peptidase in the matrix. The free
signal sequence is then degraded.
How do proteins get directed to the intermembrane space? - Answer By signal sequences only
read by the TOM complex
What is the difference between smooth ER and rough ER? - Answer -Smooth ER is responsible
for lipid synthesis.
-Rough ER is where proteins are received and translation is finished. Ribosomes attach to rough
ER.
Where does protein synthesis start? - Answer On free ribosomes in cytosol
How does a protein get directed to the ER? - Answer Signal sequence binds to SRP, SRP binds
to the SRP receptor. Protein is then pulled through protein translocator.
What does the signal recognition particle and the SRP receptor do? - Answer SRP binds to free
floating ribosome in the cytosol --> translated protein has a signal sequence that tells SRP to
bind to it. SRP receptor binds SRP that is bound to ribosome and translating protein --> moves it
to a protein translocator which moves still translating protein into the RER
What happens to the signal sequence after a protein has passed into the ER? - Answer -The
signal sequence is cleaved by signal peptidases.
-Or it's a transmembrane signal sequence ending up in the ER membrane.
How do transmembrane proteins end up in the ER membrane? - Answer Start and stop
transfer sequences or signal sequence is a transmembrane sequence.
-from protein translocator laterally transfers into the ER membrane.
What are start transfer and stop transfer signal sequences? - Answer Amino acid sequences
How are proteins that pass the membrane multiple times inserted into the ER membrane? -
Answer Through start and stop transfer sequences and the direction they are in.
How are proteins glycosylated in the ER? What are they glycosylated with? What amino acid is
and All Correct Answers (2025-2026)
Updated.
How do proteins get moved between the nucleus and the cytosol? - Answer By nuclear pore
complex. Small molecules can move across the pores via gated transport. Large molecules are
shuttled across via active transport. Nuclear import receptors bind to nuclear signal sequence.
RAN-GTP provides energy for active transport, but smaller protein will freely diffuse.
What are nuclear pore complexes? - Answer Proteins that actively transport proteins out of
the nucleus.
What is a nuclear import receptor? - Answer Soluble cytoplasmic receptors that direct
molecules to the appropriate nuclear pore complex.
What molecule delivers energy to facilitate transport of large proteins into the nucleus? What
protein is it attached to? - Answer RAN-GTP. Attached to nuclear import receptor.
Describe the subcompartments of mitochondria. - Answer Outer membrane, inner
membrane, intermembrane space, matrix.
-DNA replication occurs.
-ATP synthesis --> proton motive force.
-ATP synthase is inside the inner membrane
-Protons accumulate inside the inner membrane space and move across the inner membrane to
the matrix (ADP --> ATP)
What are protein translocators? - Answer Membrane bound proteins that mediate the
transport of another protein across an organelle membrane.
-TOM --> across outer membrane to inner membrane
-TIM --> across the inner membrane to matrix
Why does it matter that the mitochondrial signal sequence for protein import forms an alpha
helix? Describe the properties of this alpha helix. - Answer One side of the alpha helix is polar
and is recognized by receptor proteins on mitochondria.
, membranes. The signal sequence is then cleaved by a signal peptidase in the matrix. The free
signal sequence is then degraded.
How do proteins get directed to the intermembrane space? - Answer By signal sequences only
read by the TOM complex
What is the difference between smooth ER and rough ER? - Answer -Smooth ER is responsible
for lipid synthesis.
-Rough ER is where proteins are received and translation is finished. Ribosomes attach to rough
ER.
Where does protein synthesis start? - Answer On free ribosomes in cytosol
How does a protein get directed to the ER? - Answer Signal sequence binds to SRP, SRP binds
to the SRP receptor. Protein is then pulled through protein translocator.
What does the signal recognition particle and the SRP receptor do? - Answer SRP binds to free
floating ribosome in the cytosol --> translated protein has a signal sequence that tells SRP to
bind to it. SRP receptor binds SRP that is bound to ribosome and translating protein --> moves it
to a protein translocator which moves still translating protein into the RER
What happens to the signal sequence after a protein has passed into the ER? - Answer -The
signal sequence is cleaved by signal peptidases.
-Or it's a transmembrane signal sequence ending up in the ER membrane.
How do transmembrane proteins end up in the ER membrane? - Answer Start and stop
transfer sequences or signal sequence is a transmembrane sequence.
-from protein translocator laterally transfers into the ER membrane.
What are start transfer and stop transfer signal sequences? - Answer Amino acid sequences
How are proteins that pass the membrane multiple times inserted into the ER membrane? -
Answer Through start and stop transfer sequences and the direction they are in.
How are proteins glycosylated in the ER? What are they glycosylated with? What amino acid is
