On pages 149-150, Dr. Moalem discuses the importance of retroviruses and viruses in the evolution of human beings. This relates to Big Idea 1 (The process of evolution drives the diversity and unity of life) because in humans, it is found that 8% of the human genome is composed of retroviruses, or elements related to it that have found a permanent place in our DNA. Specifically, it is noted that a healthy placenta is a benefit from HERV and the skin disorder psoriasis is not.
Describe how the virus is able to be a part of the human DNA (offspring's DNA). Define and explain what a Weismann barrier is and how it relates to viruses/ retroviruses? How does a virus/retroviruses cross this barrier. Explain how the Weismann barrier keeps out certain viruses/retroviruses. Explain how the benefit of a healthy placenta is created. Explain how a hurtful effect of HERV, like psoriasis is created. Connect this with HIV. Compare and contrast the processes, effects, functions between HIV and HERV. Is HIV a type of HERV.
Crystal Chang (cchang3@students.d125.org)
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ReplyDeleteThe Weismann barrier stands between germ cells and somatic cells to prevent transferring of genetic information from somatic cells to germ cells (Moalem 142). For instance, the Weismann barrier prevents HIV to penetrate and to insert itself into the DNA of eggs or sperm (Moalem 149). However, Some retroviruses or viruses have the ability to go through the Weismann barrier and carry DNA from somatic cells to germ cells, which leads to adaptations may be passed on to future generations (Moalem 143). Human DNA can be changed by retroviruses; retroviruses, made of RNA, use an enzyme called reverse transcriptase to transcribe themselves from RNA into DNA (Moalem 149). This action of retroviruses is against the normal information flow; therefore, there will be a new gene expression from the newly modified DNA by retroviruses. Eventually, throughout the lifetime, the newly modified DNA will be transcribed into mRNA; mRNA will be translated into proteins, which will be expressed differently compared to before. Offspring of an organism will be born with the virus permanently encoded in its DNA if a retrovirus or virus writes itself into the DNA of cells in the germ line of an organism (Moalem 149). Human endogenous retroviruses (HERVs) that are permanently placed in human DNA compose at least 8 percent of the human genome; a particular human endogenous retrovirus may play an important role in the construction of a healthy placenta. On the other hand, the skin disorder psoriasis is linked to other human endogenous retroviruses: “persisting viruses” that are the viruses that have migrated into our genome over millions of years and may have become our partners in evolution, unlike HIV or smallpox (Moalem 151). This idea is related to Big Idea 1(The process of evolution drives the diversity and unity of life). Both HIV and HERVs are retroviruses that can reversely transcribe themselves into DNA from RNA. In result, after HIV and HERV encode themselves into DNA, the regulatory of proteins are different from the prior proteins because the DNA itself has been changed by retroviruses. In addition, both HIV and HERV are not considered as alive because they cannot reproduce or metabolize themselves. On the contrary, according to the scientific journal by Jin Yang et al, HIV is an exogenous retrovirus that is currently present and has been evolved present day while HERVs are the endogenous retroviruses that already had evolved in human DNA. For instance, it was estimated that “HERV-Ks first entered the primate genome shortly after the split of new world and old world monkeys (more than 30 million years ago).” Also, HERVs are generally found in human DNA; HIV is only found in human DNA of people who are affected by HIV (http://www.jstor.org/stable/49178). Lastly, HERVs may be beneficial to human, including having a healthy placenta; however, HIV is a “deadly parasite” to human.
ReplyDelete(Fabiola Yun, jooyun4@students.d125.org)
It has been believe that psoriasis occurs when the immune system mistakes a normal skin cell for a pathogen, and sends out faulty signals that cause overproduction of new skin cells. The psoriasis natural is not contagious. But most people experience with the condition can sometimes suffer from social exclusion and discrimination which is very sad to know.
ReplyDeleteI don't even know that there is psoriasis of the scalp. I thought is not psoriasis.
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