In chapter 5, I learned that an adult human contains ten times as many foreign microbial cells as mammalian cells. I also learned a lot about host manipulation in animals from spiders to humans. I found it really intriguing that the cold virus actually triggers your sneezing reflex so that it can infect others around you. Other viruses, such as cholera and some STDs, also use various degrees of host manipulation to find transmission channels. I also found it interesting that our sense of disgust at certain smells that have a load of infectious material, such as spoiled food, really helps us avoid infection. Additionally, a human’s fear of strangers (xenophobia) might be due to the instinctive avoidance of disease. A key point in chapter 5 was that the degree of virulence is determined by how a parasite gets from host to host. The final fact I learned in chapter 5 was that anthrax can exist outside a host for over ten years. In chapter 6, I learned that the first vaccine was protection from smallpox with cowpox infection. I also learned that less than 3% of your DNA contains instructions for building cells, and that a third of your DNA is derived from viruses. Additionally, I learned that humans have a total of approximately 25,000 genes. Also, I learned about jumping genes and their role in brain development and the immune system. Moreover, I read a simple description of how antibodies are built. Finally, I read that at least 8% of the human genome is composed of retroviruses, which was quite unexpected. After reading these two chapters, the questions that I still have are: why does T. gondii only have guaranteed survival in cats? Also, I don’t really understand the difference between antigenetic drift and antigenetic shift. Lastly, if the genome system react to a knocked-out gene and get a body built the same way, then why are some genetic mutations so harmful?
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