Question

Fill in the blanks that are numbered.

In alligators and many other reptiles, the gender of the offspring are determined more by the external exposure of certain hormones in the water on the eggs during development vs. the function of the _41__ chromosomes for females or the _42__ chromosome in males.
Let’s say that 85% of Floridian women in and around the Everglades water system take an estrogen based birth control. Excess estrogen is flushed into the waterways of the Everglades where it comes in contact with the growing eggs of alligators throughout the area. The development of ovaries in alligators is activated or turned on by the presence of estrogen. Thus, estrogen is acting like a __43___ to the operon of ovary development. In this operon, we might see that estrogen would bind to the normally present __44__ that keeps the expression of the ____45___genes turned off or repressed. In this repressed state, the ___46__ cannot bind to the ___47__ and transcribe the genes needed to make ovaries.

Now, with the increased amount of estrogen in the water, the ovary operon would be ___48__ and we might expect to count a higher number of __49__ alligators hatching from nests throughout the Everglades. However, in the northeast corner of the Everglades a __50____ arose from an error in the DNA replication that took place in the formation of a subpopulation of alligator gametes. These gametes now could only express a malformed ___51___ that could no longer bind to the promoter region of the ovary operon when estrogen was not present. We could thus predict that there would be a higher number of __52___ vs. males just like we saw in the above situation. Of course, the presence of a __53___ in the genomes of this subpopulation may be of more concern for the alligators since it could be propagated through multiple generations of alligator cells that have to under go ___54_____replication and then cell division through __55___to produce gametes. Whereas, we could develop a filtering system to remove the extra estrogen from the water before it returns to the water system of the Everglades and thus, the __56____ of the ovary operon would be reduced to normal levels.

Answer 1

In alligators and many other reptiles, the gender of the offspring are determined more by the external exposure of certain hormones in the water on the eggs during development vs. the function of the _41__ chromosomes for females or the _42__ chromosome in males.
Let’s say that 85% of Floridian women in and around the Everglades water system take an estrogen based birth control. Excess estrogen is flushed into the waterways of the Everglades where it comes in contact with the growing eggs of alligators throughout the area. The development of ovaries in alligators is activated or turned on by the presence of estrogen. Thus, estrogen is acting like a Inducer to the operon of ovary development. In this operon, we might see that estrogen would bind to the normally present repressor that keeps the expression of the structural genes turned off or repressed. In this repressed state, the RNA polymerase cannot bind to the promoter and transcribe the genes needed to make ovaries.

Now, with the increased amount of estrogen in the water, the ovary operon would be active and we might expect to count a higher number of female alligators hatching from nests throughout the Everglades. However, in the northeast corner of the Everglades a mutation arose from an error in the DNA replication that took place in the formation of a subpopulation of alligator gametes. These gametes now could only express a malformed repressor that could no longer bind to the promoter region of the ovary operon when estrogen was not present. We could thus predict that there would be a higher number of female vs. males just like we saw in the above situation. Of course, the presence of a mutation in the genomes of this subpopulation may be of more concern for the alligators since it could be propagated through multiple generations of alligator cells that have to under go DNA replication and then cell division through meiosis to produce gametes. Whereas, we could develop a filtering system to remove the extra estrogen from the water before it returns to the water system of the Everglades and thus, the expression of the ovary operon would be reduced to normal levels.