Cholera toxin can affect cells by inhibiting the ability of the G protein α subunit to hydrolyze GTP to GDP. On a cellular level, which one of the following would be helpful in reducing the harmful effect of cholera toxin?
a. Increasing the amount of intracellular cAMP.
b. Inhibiting the activity of adenylyl cyclase in the cell.
c. Adding ligand for the G-protein coupled receptor in this
pathway.
d. Increasing the amount of protein kinase A activity in the
cell.
e. Inhibiting the activities of the β and γ G-protein subunits.

b. Inhibiting the activity of adenylyl cyclase in the cell.

Explanation:

Cholera toxin enters the interstitial epithelial cells with the help of 5 identical B sub units and 1 A sub unit. A sub unit is catalytic and it is endocytosed in  interstitial epithelial cells.  Inside cells, A sub unit is cleaved into two fragments A1 and A2 with the help of proteases. A1 upon interaction with a small cytosolic G protein named as ARF-6 activates Gsα protein permanently by post translation modification known as ribosylation. This Gsα protein further acts upon an intracellular adenylate cyclase. The adenylate cyclase constitutively produces cyclic AMP (cAMP) which acts upon CFTR chloride ion channel and Na⁺ and H⁺ exchanger. As a result of this, large efflux of NaCl occurs. After NaCl loss, inside condition becomes hypotonic which leads to loss of water from the cells. This condition causes diarrhea .

But if activity of adenylate cyclase can be inhibited, the signaling cascade will come to an end leading to reduced harmful effect of cholera toxin.

the sphincter muscles at the end of the digestive tract is the anus.

transcription is a process in which information is rewritten. it is something our cells must do, in a more specialized and narrowly defined way. in biology, transcription is the process of copying out the dna sequence of a gene in the similar alphabet of rna. it needs to happen in the nucleus because that's where the dna is. dna is always inside the nucleus unless the cell is dividing.

transcription is the first step in gene expression, which involves copying a gene's dna sequence to make an rna molecule. transcription is performed by rna polymerases. it has three stages: initiation, elongation, and termination. rna molecules must be processed after transcription in eukaryotes.

explanation:

long version:

the protein synthesis consists two processes which are, transcription and translation. transcription takes place in the nucleus. it uses dna as a template to make an rna molecule. rna then leaves the nucleus and goes to a ribosome in the cytoplasm, where translation occurs. transcription is the first part of the central dogma of molecular biology: dna → rna. it is the transfer of genetic instructions in dna to messenger rna (mrna). during transcription, a strand of mrna is made that is complementary to a strand of dna.  

these three stages are:

  initiation: in which   is the beginning of transcription.occuring when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

    elongation: in which is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

    termination: in which is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.