The major virulence factor produced by c. diphtheriae is diphtheria toxin. the production of diphtheria toxin during infection is controlled by a repressor, dtxr. the activity of dtxr is regulated by iron, which acts as a corepressor. during an infection, the levels of iron available in the tissues for use by c. diphtheriae are low. what effect will the decreased iron availability have on the production of diphtheria toxin
a. the lack of corepressor binding to dtxr will lead to a loss of repression and an increase in the production of toxin.
b. the corepressor will not be able to interact with the operator and will cause an increase in the production of toxin.
c. the repressor will not be active, therefore toxin production will decrease.
d. without the compressor to interact with the operator, the repressor will stay bound to the promoter leading to a decrease in the amount of toxin.

The answer to the question: What effect will the decreased iron availability have on the production of diphteria toxin, would be, A: The lack of co-repressor binding to DtxR will lead to a loss of repression and an increase in the production of toxin.

Explanation:

Diphteria is a very serious disease that is caused by the gram-negative bacteria Corynebacterium Diphtheriae, which attacks the upper respiratory tract, especially the throat, and causes a thick lining to form, complicating the normal respiratory function. In order to accomplish such a feat, this bacteria produces a toxin that attacks human cells. But the toxin will not be produced if there is a high availability of iron in the area where the bacteria intends to infect, because if that is the case, then iron will work as a co-repressor with DtxR to prevent the expression of the bacterial gene that codes for the toxin. A co-repressor means that iron will work as a coadjuvant for DtxR and will not allow the genes of the bacteria to produce the toxin. In the case of this question, the answer is A because we have a lack of iron availability, which means that DtxR will not be enough to stop the toxin from being produced.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.