BIOL 3000 Exam 2 Study Questions And
100% Accurate Answers.
What do the vast majority of proteins routed through the secretory pathway have in common?
A. They will be secreted.
B. The are post-translationally targeted to their final destination.
C. They are initially post-translationally inserted into the endoplasmic reticulum (ER) lumen.
D. They are co-translationally inserted into the ER lumen. - Answer D. They are co-translationally
inserted into the ER lumen.
Feedback: Fig. 13-1
Which of the following accurately describes targeting proteins to the mitochondrial matrix or the
nucleus?
A. Both mitochondrial matrix and nuclear proteins are co-translationally targeted to their destinations.
B. Both mitochondrial matrix and nuclear proteins are folded only after they reach their destinations.
C. Proteins targeted to the nucleus are completely folded in the cytoplasm. Proteins targeted to the
mitochondrial matrix are unfolded while being inserted into the mitochondria and are refolded within
the matrix.
D. Proteins targeted to the mitochondrial matrix are completed folded in the cytoplasm. Proteins
targeted to the nucleus are unfolded while being inserted into the nucleus and are refolded within the
nucleus.
E. None of these statements are correct. - Answer D. Proteins targeted to the mitochondrial matrix are
completed folded in the cytoplasm. Proteins targeted to the nucleus are unfolded while being inserted
into the nucleus and are refolded within the nucleus.
Feedback: Fig. 13-1
Which method or combination of methods would you use to optimally separate nuclei and mitochondria
from each other?
A. Differential centrifugation
B. Equilibrium density-gradient centrifugation
,C. ion exchange chromatography
D. (a) and (b)
E. (a) (b) and (c) - Answer A. Differential centrifugation
Feedback: Figs. 4-36, 4-37
Humans have 3 primary lipid transport particles that differ by mass (in kDa) and protein:lipid ratios: VLDL
(very low density lipoprotein particles) ~10 kDa; protein:lipid = 1:100 LDL (low density lipoprotein
particles) ~ 2 kDa; protein:lipid = 25:100 HDL (high density lipoprotein particles) ~0.2 kDa; protein:lipid =
90:100 Which combination of the following procedures would you use to most completely
separate/purify intact (no-denatured) VLDL, LDL and HDL particles from each other?
A. Equilibrium-density gradient sedimentation + SDS-PAGE.
B. Equilibrium-density gradient sedimentation + gel filtration (exclusion) chromatography.
C. Equilibrium-density gradient sedimentation + ion exchange chromatography.
D. Gel filtration (exclusion) chromatography + differential centrifugation.
E. Ion exchange chromatography + SDS-PAGE - Answer B. Equilibrium-density gradient sedimentation +
gel filtration (exclusion) chromatography.
Feedback: Figs. 4-36, 4-37, 3-40
The figure below shows the structure of the commonly used ion exchange DEAE (Diethyl-amino-ethyl) at
neutral pH. You want to separate the following mixture of 3 polypeptides on a DEAE column: Peptide 1:
MSRNVIKDCKTERYF Peptide 2: MEQNVNQDCKTERYD Peptide 3: MKDHSELDCEHEDHF What will be the
order in which these peptides elute from the column as you progressively increase the concentration of
KCl in pH 7.0 buffer applied to the column. To keep it simple, we'll just refer to low salt; medium salt;
high salt eluted fractions.
DEAE.pdf 9 KB
A. Peptide 1 low salt; Peptide 2 medium salt; Peptide 3 high salt.
B. Peptide 1 low salt; Peptide 3 medium salt; Peptide 2 high salt.
C. Peptide 2 low salt; Peptide 1 medium salt; Peptide 3 high salt.
D. Peptide 2 low salt; Peptide 3 medium salt; Peptide 1 high salt.
E. Peptide 3 low salt; Peptide 1 medium salt; Peptide 2 high salt.
, F. Peptide 3 low salt; Peptide 2 medium - Answer A. Peptide 1 low salt; Peptide 2 medium salt; Peptide
3 high salt.
Feedback: Peptide 1 has an overall charge of +2 at neutral pH so it will only bind weakly to the DEAE
column. Peptide 2 has an overall charge of -2 at neutral pH so it binds more tightly than Peptide 1, but
less tightly than Peptide 3 which has an overall charge of -5 at neutral pH. The 3 Histidines in peptide 3
do not influence its charge at neutral pH. If the experiment was performed in pH 5.0 buffer, then the
Histidines in peptide 3 would be protonated reducing its overall negative charge from -5 to -2. It would
then co-elute with peptide 2 in medium salt.
Indirect immunofluorescence microscopy utilizes:
A. A fluorescently tagged primary antibody that binds by its Fc region to an epitope on its corresponding
antigen.
B. A fluorescently tagged primary antibody that binds by its CDR to an epitope on its corresponding
antigen.
C. A fluorescently tagged secondary antibody that binds by its CDR to the Fc region of a primary
antibody bound by its CDR to an epitope on its corresponding antigen.
D. A fluorescently tagged secondary antibody that binds by its Fc region to the CDR of a primary
antibody bound by its Fc region to an epitope on its corresponding antigen.
E. A GFP-tagged protein that is directly visualized in a living cell. - Answer C. A fluorescently tagged
secondary antibody that binds by its CDR to the Fc region of a primary antibody bound by its CDR to an
epitope on its corresponding antigen.
Feedback: Fig. 4-14
How would you use epifluorescence microscopy to examine the localization of a chimeric GFP fusion
protein in a living cell? The λexcite for GFP is 395 nm & λemission is 509 nm.
A. Irradiate or illuminate the cell at 395 nm & view it at 509 nm.
B. Irradiate or illuminate the cell at 509 nm & view it at 395 nm.
C. Just view the cell at 395 nm as GFP is self-fluorescing.
D. Just view the cell at 509 nm as GFP is self-fluorescing. - Answer A. Irradiate or illuminate the cell at
395 nm & view it at 509 nm.
Feedback: Fig. 4-9
100% Accurate Answers.
What do the vast majority of proteins routed through the secretory pathway have in common?
A. They will be secreted.
B. The are post-translationally targeted to their final destination.
C. They are initially post-translationally inserted into the endoplasmic reticulum (ER) lumen.
D. They are co-translationally inserted into the ER lumen. - Answer D. They are co-translationally
inserted into the ER lumen.
Feedback: Fig. 13-1
Which of the following accurately describes targeting proteins to the mitochondrial matrix or the
nucleus?
A. Both mitochondrial matrix and nuclear proteins are co-translationally targeted to their destinations.
B. Both mitochondrial matrix and nuclear proteins are folded only after they reach their destinations.
C. Proteins targeted to the nucleus are completely folded in the cytoplasm. Proteins targeted to the
mitochondrial matrix are unfolded while being inserted into the mitochondria and are refolded within
the matrix.
D. Proteins targeted to the mitochondrial matrix are completed folded in the cytoplasm. Proteins
targeted to the nucleus are unfolded while being inserted into the nucleus and are refolded within the
nucleus.
E. None of these statements are correct. - Answer D. Proteins targeted to the mitochondrial matrix are
completed folded in the cytoplasm. Proteins targeted to the nucleus are unfolded while being inserted
into the nucleus and are refolded within the nucleus.
Feedback: Fig. 13-1
Which method or combination of methods would you use to optimally separate nuclei and mitochondria
from each other?
A. Differential centrifugation
B. Equilibrium density-gradient centrifugation
,C. ion exchange chromatography
D. (a) and (b)
E. (a) (b) and (c) - Answer A. Differential centrifugation
Feedback: Figs. 4-36, 4-37
Humans have 3 primary lipid transport particles that differ by mass (in kDa) and protein:lipid ratios: VLDL
(very low density lipoprotein particles) ~10 kDa; protein:lipid = 1:100 LDL (low density lipoprotein
particles) ~ 2 kDa; protein:lipid = 25:100 HDL (high density lipoprotein particles) ~0.2 kDa; protein:lipid =
90:100 Which combination of the following procedures would you use to most completely
separate/purify intact (no-denatured) VLDL, LDL and HDL particles from each other?
A. Equilibrium-density gradient sedimentation + SDS-PAGE.
B. Equilibrium-density gradient sedimentation + gel filtration (exclusion) chromatography.
C. Equilibrium-density gradient sedimentation + ion exchange chromatography.
D. Gel filtration (exclusion) chromatography + differential centrifugation.
E. Ion exchange chromatography + SDS-PAGE - Answer B. Equilibrium-density gradient sedimentation +
gel filtration (exclusion) chromatography.
Feedback: Figs. 4-36, 4-37, 3-40
The figure below shows the structure of the commonly used ion exchange DEAE (Diethyl-amino-ethyl) at
neutral pH. You want to separate the following mixture of 3 polypeptides on a DEAE column: Peptide 1:
MSRNVIKDCKTERYF Peptide 2: MEQNVNQDCKTERYD Peptide 3: MKDHSELDCEHEDHF What will be the
order in which these peptides elute from the column as you progressively increase the concentration of
KCl in pH 7.0 buffer applied to the column. To keep it simple, we'll just refer to low salt; medium salt;
high salt eluted fractions.
DEAE.pdf 9 KB
A. Peptide 1 low salt; Peptide 2 medium salt; Peptide 3 high salt.
B. Peptide 1 low salt; Peptide 3 medium salt; Peptide 2 high salt.
C. Peptide 2 low salt; Peptide 1 medium salt; Peptide 3 high salt.
D. Peptide 2 low salt; Peptide 3 medium salt; Peptide 1 high salt.
E. Peptide 3 low salt; Peptide 1 medium salt; Peptide 2 high salt.
, F. Peptide 3 low salt; Peptide 2 medium - Answer A. Peptide 1 low salt; Peptide 2 medium salt; Peptide
3 high salt.
Feedback: Peptide 1 has an overall charge of +2 at neutral pH so it will only bind weakly to the DEAE
column. Peptide 2 has an overall charge of -2 at neutral pH so it binds more tightly than Peptide 1, but
less tightly than Peptide 3 which has an overall charge of -5 at neutral pH. The 3 Histidines in peptide 3
do not influence its charge at neutral pH. If the experiment was performed in pH 5.0 buffer, then the
Histidines in peptide 3 would be protonated reducing its overall negative charge from -5 to -2. It would
then co-elute with peptide 2 in medium salt.
Indirect immunofluorescence microscopy utilizes:
A. A fluorescently tagged primary antibody that binds by its Fc region to an epitope on its corresponding
antigen.
B. A fluorescently tagged primary antibody that binds by its CDR to an epitope on its corresponding
antigen.
C. A fluorescently tagged secondary antibody that binds by its CDR to the Fc region of a primary
antibody bound by its CDR to an epitope on its corresponding antigen.
D. A fluorescently tagged secondary antibody that binds by its Fc region to the CDR of a primary
antibody bound by its Fc region to an epitope on its corresponding antigen.
E. A GFP-tagged protein that is directly visualized in a living cell. - Answer C. A fluorescently tagged
secondary antibody that binds by its CDR to the Fc region of a primary antibody bound by its CDR to an
epitope on its corresponding antigen.
Feedback: Fig. 4-14
How would you use epifluorescence microscopy to examine the localization of a chimeric GFP fusion
protein in a living cell? The λexcite for GFP is 395 nm & λemission is 509 nm.
A. Irradiate or illuminate the cell at 395 nm & view it at 509 nm.
B. Irradiate or illuminate the cell at 509 nm & view it at 395 nm.
C. Just view the cell at 395 nm as GFP is self-fluorescing.
D. Just view the cell at 509 nm as GFP is self-fluorescing. - Answer A. Irradiate or illuminate the cell at
395 nm & view it at 509 nm.
Feedback: Fig. 4-9
