Please see link for image of the problem: https://i.imgsafe.org/acb03acb2a.png a. A geneticist has devised a strategy to study protein translocation into the endoplasmic reticulum (ER) in yeast cells. She is interested in two different signal sequences that are thought to operate via slightly different translocation mechanisms. Using genetic engineering, she has fused the first signal sequence to a protein whose cytosolic expression is absolutely necessary for cell survival in the selective medium, but is inactive when in the ER. In the same cell, she has also fused the second signal sequence to a toxic protein whose cytosolic expression leads to cell lysis but is harmless when in the Whereas wild-type cells undergo lysis upon the expression ofthese fusion proteins, she has been able to identify viable mutants, each of which has a loss-of-function mutation in a gene encoding a protein involved in membrane translocation. The products of these genes are probably involved In the general transport of protelns Into the ER regardless of the type of signal sequence. involved in the transport of proteins with the first signal sequence but not the second one. Involved In the transport of protelns with tne second signal sequence but not the first one Involved in the transport of protelns with a novelsignal sequence (l.e.nether the first signal sequence nor the second one- 9. In the following graph, the magnitude of concentration difference across the nuclear pore complexes (NPCs) is plotted for four molecules (A to D) as a function of time, starting from an arbitrarily chosen initial concentration difference. Which of the following curves describes: 1) a large protein that is being actively transported across the NPC and 2) a large protein that is NOT actively transported into or out of the nucleus 10 Time (min) 1A, 2C 10. Considering the following hydropathy plot for a protein with 4 transmembrane domain. This protein functions in the plasma membrane. The position of positively charged residues near the first transmembrane helixis indicated by an asterisk on the plot. Are the protein termini expected to be located inside (l) or outside (O of the cell? Which of the regions indicated as 2 and 3 in the plot is expected to have more positively charged residues? Hydropathy index 1000 200 Residue number O, 2 Solution 8. A geneticist has devised a strategy to study protein translocation into the endoplasmic reticulum (ER) in yeast cells. She is interested in two different signal sequences that are thought to operate via slightly different translocation mechanisms. Using genetic engineering, she has fused the first signal sequence to a protein whose cytosolic expression is absolutely necessary for cell survival in the selective medium, but is inactive when in the ER. In the same cell, she has also fused the second signal sequence to a toxic protein whose cytosolic expression leads to cell lysis but is harmless when in the ER. Whereas wild-type cells undergo l.

1. Please see link for image of the problem:
https://i.imgsafe.org/acb03acb2a.png a. A geneticist has devised a strategy to study protein
translocation into the endoplasmic reticulum (ER) in yeast cells. She is interested in two different
signal sequences that are thought to operate via slightly different translocation mechanisms.
Using genetic engineering, she has fused the first signal sequence to a protein whose cytosolic
expression is absolutely necessary for cell survival in the selective medium, but is inactive when
in the ER. In the same cell, she has also fused the second signal sequence to a toxic protein
whose cytosolic expression leads to cell lysis but is harmless when in the Whereas wild-type
cells undergo lysis upon the expression ofthese fusion proteins, she has been able to identify
viable mutants, each of which has a loss-of-function mutation in a gene encoding a protein
involved in membrane translocation. The products of these genes are probably involved In the
general transport of protelns Into the ER regardless of the type of signal sequence. involved in
the transport of proteins with the first signal sequence but not the second one. Involved In the
transport of protelns with tne second signal sequence but not the first one Involved in the
transport of protelns with a novelsignal sequence (l.e.nether the first signal sequence nor the
second one- 9. In the following graph, the magnitude of concentration difference across the
nuclear pore complexes (NPCs) is plotted for four molecules (A to D) as a function of time,
starting from an arbitrarily chosen initial concentration difference. Which of the following curves
describes: 1) a large protein that is being actively transported across the NPC and 2) a large
protein that is NOT actively transported into or out of the nucleus 10 Time (min) 1A, 2C 10.
Considering the following hydropathy plot for a protein with 4 transmembrane domain. This
protein functions in the plasma membrane. The position of positively charged residues near the
first transmembrane helixis indicated by an asterisk on the plot. Are the protein termini expected
to be located inside (l) or outside (O of the cell? Which of the regions indicated as 2 and 3 in the
plot is expected to have more positively charged residues? Hydropathy index 1000 200 Residue
number O, 2
Solution
8. A geneticist has devised a strategy to study protein translocation into the endoplasmic
reticulum (ER) in yeast cells. She is interested in two different signal sequences that are thought
to operate via slightly different translocation mechanisms. Using genetic engineering, she has
fused the first signal sequence to a protein whose cytosolic expression is absolutely necessary for
cell survival in the selective medium, but is inactive when in the ER. In the same cell, she has
also fused the second signal sequence to a toxic protein whose cytosolic expression leads to cell

2. lysis but is harmless when in the ER. Whereas wild-type cells undergo lysis upon the expression
of these fusion proteins, she has been able to identify viable mutants, each of which has a loss-
of-function mutation in a gene encoding a protein involved in membrane translocation. The
products of these genes are probably ...
A. involved in the general transport of proteins into the ER, regardless of the type of signal
sequence.
B. involved in the transport of proteins with the first signal sequence but not the secondone.
C. involved in the transport of proteins with the second signal sequence but not the first one.
D. involved in the transport of proteins with a novel signal sequence (i.e. neither the first signal
sequence
nor the second one).
Answer is option B.
9. In the following graph, the magnitude of concentration difference across the nuclear pore
complexes (NPCs) is plotted for four molecules (A to D) as a function of time, starting from an
arbitrarily chosen initial concentration difference. Indicate which curve corresponds to each of
the following molecules. Your answer would be a four-letter string composed of letters A to D
only, e.g. ABCD
Answer is Option A
10. Considering the following hydropathy plot for a protein with 4 transmembrane domain. This
protein functions in the plasma membrane. The position of Positively charged residues near the
first transmembrane helix is indicated by an asterisk on the plot?
Which of the regions indicated as 2 and 3 in the plot is expected to have positively charged
residues?
Answer is option B. I,3
curves below the line shows us they are internal which are hydrophobic and above curves shows
they are hydrophillic and Outer membrane. Both the curves are below the line in the graph, so I
..Inside the cell
More the positively charged residues, they repel each other so the curve should be broader/
bigger. So 3 is the answer.