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- Mon Feb 27, 2017 4:35 pm
#33163
Passage Discussion
Paragraph One:
The author opens the first passage with the definition of an infection: when a pathogen, or disease causing agent, creates a “viable presence” in an organism, an occurrence that necessitates the pathogen’s being able to reproduce within the host. “Until recently,” the author provides, it was believed that only four agents could cause infection: 1) viruses; 2) bacteria; 3) fungi; and 4) parasites, all of which reproduce and live using genetic material made up of nucleic acid, specifically either DNA or RNA. As such, the corresponding belief was that all pathogens have such genetic material.
Paragraph Two:
The second paragraph opens with the basis for a challenge to the beliefs discussed above (not surprising, given the author’s use of the foreshadowing term, “until recently” in the first paragraph): Creutzfeldt-Jakob disease, or CJD, is a type of degenerative dementia which creates tiny holes in the brain, suggesting the death of a significant number of nerve cells. Four symptoms of the disease are then listed: loss of muscle control, mental sharpness, and memory, as well as chronic insomnia. The pathogen that causes CJD appears to be comprised primarily of protein rather than nucleic acid, like the other four types of disease-causing agents discussed in the first paragraph. Researchers named the protein pathogen “prion.”
Paragraph Three:
Here the author continues the discussion of the prions, which normally appear in many body tissues as harmless protein cells but are able to transform into a dangerous shape and can lead to a chain reaction, changing normal prions into pathogenic ones on contact. The pathogenic prions create a thread-like plaque that eventually destroys nerve cells as it collects in the brain. Further, the body’s immune system does not react to prions as it does other pathogens, because prions are proteins that are normally present in the body. Since there is no effective way to fight the prion reproductive chain reaction, CJD is always eventually fatal, although the disorder varies both in degree of aggressiveness and incubation time.
Paragraph Four:
After initial skepticism regarding the link between prions and CJD, research has provided support for the characterization of prions as a new class of pathogen, and while prions’ processes of reproduction and destruction are not completely understood, similar protein malformation is thought to be involved in more common conditions such as Alzheimer’s and Parkinson’s.
VIEWSTAMP Analysis:
The only Viewpoints presented in this passage are those of the author, who simply presents the facts, and of the general scientific community.
The Tone of the passage is well-reasoned and somewhat academic; the author provides a scholarly presentation of recent scientific pathogen research.
The Structure of the passage is as follows:
Paragraph One:
The author opens the first passage with the definition of an infection: when a pathogen, or disease causing agent, creates a “viable presence” in an organism, an occurrence that necessitates the pathogen’s being able to reproduce within the host. “Until recently,” the author provides, it was believed that only four agents could cause infection: 1) viruses; 2) bacteria; 3) fungi; and 4) parasites, all of which reproduce and live using genetic material made up of nucleic acid, specifically either DNA or RNA. As such, the corresponding belief was that all pathogens have such genetic material.
Paragraph Two:
The second paragraph opens with the basis for a challenge to the beliefs discussed above (not surprising, given the author’s use of the foreshadowing term, “until recently” in the first paragraph): Creutzfeldt-Jakob disease, or CJD, is a type of degenerative dementia which creates tiny holes in the brain, suggesting the death of a significant number of nerve cells. Four symptoms of the disease are then listed: loss of muscle control, mental sharpness, and memory, as well as chronic insomnia. The pathogen that causes CJD appears to be comprised primarily of protein rather than nucleic acid, like the other four types of disease-causing agents discussed in the first paragraph. Researchers named the protein pathogen “prion.”
Paragraph Three:
Here the author continues the discussion of the prions, which normally appear in many body tissues as harmless protein cells but are able to transform into a dangerous shape and can lead to a chain reaction, changing normal prions into pathogenic ones on contact. The pathogenic prions create a thread-like plaque that eventually destroys nerve cells as it collects in the brain. Further, the body’s immune system does not react to prions as it does other pathogens, because prions are proteins that are normally present in the body. Since there is no effective way to fight the prion reproductive chain reaction, CJD is always eventually fatal, although the disorder varies both in degree of aggressiveness and incubation time.
Paragraph Four:
After initial skepticism regarding the link between prions and CJD, research has provided support for the characterization of prions as a new class of pathogen, and while prions’ processes of reproduction and destruction are not completely understood, similar protein malformation is thought to be involved in more common conditions such as Alzheimer’s and Parkinson’s.
VIEWSTAMP Analysis:
The only Viewpoints presented in this passage are those of the author, who simply presents the facts, and of the general scientific community.
The Tone of the passage is well-reasoned and somewhat academic; the author provides a scholarly presentation of recent scientific pathogen research.
The Structure of the passage is as follows:
- Paragraph 1:
Define “infection,” provide the list of four infectious agents that was previously believed to include every category.
Paragraph 2: Introduce example of Creutzfeldt-Jakob disease and the concept of the prion, a recently discovered protein pathogen.
Paragraph 3: Discuss more on the topic of prions, the effects of pathogenic prions, and the fact that a lack of response from the immune system means that the disease is always fatal.
Paragraph 4: Close the passage with the fact that prions have, after initial skepticism, been characterized as a new class of pathogen, and that other more common conditions are now believed to be attributable to similar protein malformations.