What are the main organs affected by cystic fibrosis? correct answers Lungs, any organ that has epithelial cells, mucus, and secretory system which requires regulation of that mucus
Describe the main function of the CFTR protein and how it is regulated. correct answers responsible for regulating...
NROS 310 EXAM 1 || WITH ACCURATE ANSWERS
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What are the main organs affected by cystic fibrosis? correct answers Lungs, any organ that has
epithelial cells, mucus, and secretory system which requires regulation of that mucus
Describe the main function of the CFTR protein and how it is regulated. correct answers
responsible for regulating the proper flow of chloride and sodium (a component of salt) in and
out of the cell membranes in the lungs and other organs. It is regulated by its cytosolic domains:
two nucleotide binding domains (NBDs) and a regulatory (R) domain.
Why does the most common CF mutation cause a loss of function? correct answers It disrupt the
function of the chloride channels, preventing them from regulating the flow of chloride ions and
water across cell membranes.
Describe how a defect in the CFTR leads to the problems in cystic fibrosis. correct answers Cells
that line the passageways of the lungs, pancreas, and other organs produce mucus that is
unusually thick and sticky.
Outline three ways to treat patients with Cystic Fibrosis. correct answers medicines to make the
mucus in the lungs thinner and easier to cough up.
medicines to widen the airways and reduce inflammation.
special techniques and devices to help clear mucus from the lungs.
What is cholera: what is it caused by and how does it affect the body? correct answers Ingestion
of dirty water → results in dehydration.Over activation of cAMP by inhibition of G-subunit
leading to outflux of Chlorine. This leads to dehydration.
Why is glucose + sodium an effective treatment for cholera? correct answers Lessens
dehydration through Sodium-Glucose Transporter.
Would a heterozygote for a CFTR mutation be resistant to cholera? What about someone who
was homozygous for the CF mutation? correct answers they would have half of the affected
CFTR, making dehydration occur slower, leading to less dehydration.
How do proteins get to the appropriate target(s) within the cell correct answers signal sequences
What kinds of molecules can pass unaided through the nuclear pore complex? correct answers
small nonpolar
What is the nature of the nuclear localization signal? correct answers act as a signal fragment that
mediates the transport of proteins from the cytoplasm into the nucleus
Design an experiment to show that a given signal sequence is both necessary and sufficient to
target a protein to the nucleus. correct answers To show that its necessary, knockout the targeting
, sequence. If it still goes to the nucleus its not necessary, but if it does, it is necessary. To show
that it's sufficient, put the targeting sequence in a different molecule. If it still goes to the
nucleus, its sufficient, if it goes somewhere else, its not sufficient.
What does it mean if your results show that a signal for protein localization is necessary but not
sufficient for appropriate targeting? correct answers You need that piece of protein but you need
it in combination with other missing protein to properly target.
What is the difference between a signal patch and a signal sequence? correct answers a signal
patch is made up of signal sequences and the protein must fold in the correct conformation to
work
Can nuclear localization signals be regulated? If so, how? correct answers can be regulated by
phosphorylation at these sites
Why is it important that proteins get targeted to the right cellular location? correct answers
Different proteins have different functions and in order for the cell to function properly they
must be delivered to the correct location
Describe how small G proteins are regulated. correct answers G proteins are regulated by factors
that control their ability to bind and hydrolyze GTP and GDP. When they bind GTP they are
"on" and when they bind GDP they are "off"
Describe how the actions of RAN mediate import of proteins into the nucleus. correct answers -
RAN mediates import of proteins into the nucleus by binding to GTP-First importin binds to the
NLS of a cargo protein, forming a bimolecular cargo complex. The cargo complex diffuses
through the NPC by transiently interacting with FG-nucleoporins. In the nucleoplasm RAN GTP
binds to the importin which causes a conformational change that decrecreases its affinity for the
NLS and releasing the cargo. The RAN GTP complex then diffuses back through the NPC. Once
the nuclear transport receptor Ran GTP complex reaches the cytoplasmic side of the NPC. Ran
GTP, interacts with Ran GAP. Rans GTP gets hydrolized to GDP which has low affinity for the
nuclear transport receptor, so that the free nuclear transport receptor is released into the
cytoplasm where it can participate in another cycle of import
Describe how the actions of RAN mediate export of proteins into the nucleus. correct answers In
the nucleus, the exportin binds the cargo and Ran GTP and diffuses through the pore to the
cytoplasm, where the complex dissociates. Ran GTP binds GAP and hydrolyzes GTP, and the
resulting Ran GDP complex is restored to the nucleus where it exchanges its bound ligand for
GTP. Hence, whereas importins depend of Ran GTP to dissociate from their cargo, exportins
require Ran GTP in order to bind to their cargo
Describe how the localization of Ran GAP and Ran GEF regulate nuclear import and export.
correct answers Localization of the Ran-GAP and -GEF to the cytoplasm and nucleus,
respectively, is the basis for unidirectional transport of cargo proteins across the NPC
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