Thursday, July 15, 2010

Chapter 6

20. Briefly discuss the following terms/scientists:
a. Dr. Edward Jenner was a country physician during the eighteenth century in England. He noticed that milkmaids who contracted cowpox had immunity to the very deadly infection of smallpox. A cowpox infection protected those infected from smallpox as well. Dr. Jenner had unveiled the first vaccination known to humans.

b.The first vaccination was derived from the cowpox infection to treat smallpox. A vaccine uses a mild or harmless version of a virus, so that the immune system can produce and store antibodies that are prepared to attack once the threatening virus invades the body.

c. Antibodies are created by the immune system with the purpose of defense against a harmful virus or unknown intruder in the body. Antibodies are only stored in the body once they have been exposed to the virus. Through a vaccine, antibodies are stored and are prepared to fight any sort of real infection that comes their way.

d. B-cells are a type of white blood cells that aid in the production of antibodies on behalf of the immune system. They are a building block for antibodies because of they snip and reconstruct certain parts of their DNA to adhere to the necessary requirements for a certain antibody.

e. “Junk DNA” refers to the 97 percent of an entire person’s DNA that is not directly responsible for coding proteins that enable cells to be built. As research has progressed, many scientist have taken the “junk” out of its title, for the importance of noncoding DNA has increased. Nearly half of all noncoding DNA are jumping genes, which are closely tied with specific viruses. This means that a great amount of human DNA has components of an evolved form of viruses.

f. Lamarck was a scientist who actually turned out to be more of a philosopher. He was wrongly tied to the idea of inherited acquired traits, which stated that traits acquired by parents in their lifetime would be passed along to their offspring. He promoted this idea, along with the notion of evolution. The idea that he is famously linked to has also found a connection with jumping genes and traits that are passed down a generation.

g. Barbara McCLintlock was an avid researcher in the area of genetics, and focused a lot of her research in corn. She discovered sequences of DNA changing and placing themselves in active gene slots as the environment put stress on the organism. This phenomenon seemed like an intentional mutation, and is often known as “jumping genes”. Despite the skepticism that she received when she first introduced the idea to fellow scientists in the 1950s, she eventually gained the acclaim that she deserved at the age of 81 with a Nobel Prize.

h. The usual replication process calls for DNA to various forms of RNA. Retroviruses are made of RNA, which means that they are transcribed into RNA. something that is the opposite of the information replication process. Retroviruses have the ability to transform a person’s DNA due to the use of reverse transcriptase and rapid reproduction. Because retroviruses are embedded into one’s DNA, they are passed onto further generations- unless they are harmful.

21. What is the Weissman barrier?

The Weissman barrier can be seen as a semi-permeable membrane between germ cells and somatic cells. Germ cells contain information to be passed onto further generations, the prominent cells are the egg and sperm. Somatic cells are every other cell in the body. The Weissman barrier maintains the idea that information from the somatic cells can never be passed onto germ cells.

22. Make connections with the following terms:
a.Transposons and viruses use the same replication process in the body. They use a cut and paste process that often result into mutations. Since DNA transposons (a type of jumping gene) are so similar to viruses, it means that certain viruses have been integrated into the human gene pool through the works of evolution. This means that the viruses linked to the jumping genes have shaped up to behave in a positive way to indivduals through the works of evolution.

b. Flu epidemics and outbreaks are thought to be caused by antigenic shifts and drifts. Antigenic drifts occur when there are mutations in the DNA of a virus. The mutations can be caused by radiation, which is emitted at excessive amounts by the sun. The flaring of sunspots codes for more antigenic drift, which means results to an epidemic or outbreak.

23. Humans have about 25,000 genes and more than a million different antibodies. How is this possible?

Every virus or intruder in the body requires a specific type of antibody formed by a B-cell to fight it. Since the number of viruses out number the amount of genes that humans have, it only makes sense to have more antibodies, so that the human body can prevail in a battle against foreign intruders.

24. What is a persisting virus?

Persisting viruses have migrated into our genome for over millions of years and have established themselves as our evolutionary partners in crime. As the persisting viruses seek shelter in our genes, they have an interest in a continuous and prosperous evolutionary pathway for human beings. Since viruses have the ability to replicate at unprecedented rates, they are able to produce great amounts of valuable genes that aid in human survival and evolution at higher rates than we could ever do

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