Aquaporins exclude passage of hydronium ions (h3o+), but some aquaporins allow passage of glycerol, a three-carbon alcohol, as well as h2o. since h3o+ is closer in size to water than glycerol is, yet cannot pass through, what might be the basis of this selectivity?

The maintenance of electrochemical potentials can be disturbed if protons freely pass through the membrane protein. Aquaporins are proteins that form a channel to allow passage of water molecules and some uncharged molecules as glycerol, but not of hydronium ions.  The way aquaporins exclude the entry of protons (H3O+), seems to be determined by the amino acid composition of the implicated polypeptide chains, and also dipoles.

Explanation:

Aquaporins forming a tetramere, for example AQP-1, is known.  Its monomers, consisting of 6 transmembrane helical segments and 2 short helices, each containing the sequence Asn-Pro-Ala (NPA), forming transmembrane pores.  NPA are hydrophobic amino acids.  

Crucial residues of Arg and His, and electric dipoles occurring in the short helices of NPA loops supply positive charges in positions that reject a possible protons pass through the pore.   Particularly, charged positive ions (as histidine, arginine, or lysine) in certain sections of the aquaporins, repel those H3O+, as they share  similar charges.  

1.consider the following balanced equation and answer parts a through. show calculations for each part.  

3 ag(s) + 4 hno3(aq) → 3 agno3(aq) + no(g) + 2 h2o(l)  

a. calculate the number of moles of agno3 produced by the reaction of 3 moles of ag with excess hno3. if the number to the left of the compound represents the number of moles of the compound which are present, then 3 moles of ag react with 4 moles hno3 to produce 3 moles agno3 (aq).

so the answer to a would be 3 moles.

b. calculate the number of moles of agno3 produced by the reaction of 108 grams of ag with excess hno3.  

i'm not sure how to plug in the grams of silver into an equation using moles to find how many moles are produced.

c. calculate the number of grams of agno3 produced by the reaction of 108 grams of ag with excess hno3  

d. calculate the number of moles of no produced as a byproduct of the reaction of 108 grams of ag with excess hno3.  

e. calculate the number of grams of no produced as a byproduct starting with 108 grams of ag and excess hno3.  

explanation:

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:  

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them