Parkinsons Disease

[goelmohit2002]

Hi All,

In the below question, OA = D....can someone please tell why not B ?

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Symptoms of Parkinson’s Disease, such as tremors, are thought to be caused by low dopamine levels in the brain. Current treatments of Parkinson’s disease are primarily reactionary, aiming to replenish dopamine levels after dopamine-producing neurons in the brain have died. Without a more detailed understanding of the behavior of dopamine-producing neurons, it has been impossible to develop treatments that would prevent the destruction of these neurons in Parkinson’s patients.

Recent research provides insight into the inner workings of dopamine-producing neurons, and may lead to a new drug treatment that would proactively protect the neurons from decay. By examining the alpha-synuclein protein in yeast cells, scientists have determined that toxic levels of the protein have a detrimental effect on protein transfer within the cell. More specifically, high levels of alpha-synuclein disrupt the flow of proteins from the endoplasmic reticulum, the site of protein production in the cell, to the Golgi apparatus, the component of the cell that modifies and sorts the proteins before sending them to their final destinations within the cell. When the smooth transfer of proteins from the endoplasmic reticulum to the Golgi apparatus is interrupted, the cell dies.

With this in mind, researchers conducted a genetic screen in yeast cells in order to identify any gene that works to reverse the toxic levels of alpha-synuclein in the cell. Researchers discovered that such a gene does in fact exist, and have located the genetic counterpart in mammalian nerve cells, or neurons. This discovery has led to new hopes that drug therapy could potentially activate this gene, thereby suppressing the toxicity of alpha-synuclein in dopamine-producing neurons.

While drug therapy to suppress alpha-synuclein has been examined in yeast, fruitflies, roundworms, and cultures of rat neurons, researchers are hesitant to conclude that such therapies will prove successful on human patients. Alpha-synuclein toxicity seems to be one cause for the D€@th of dopamine-producing neurons in Parkinson’s patients, but other causes may exist. Most scientists involved with Parkinson’s research do agree, however, that such promising early results provide a basis for further testing.

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It can be inferred from the passage that a yeast cell with toxic levels of alpha-synuclein will die because

a) low levels of dopamine will disrupt the flow of proteins from the endoplasmic reticulum to the Golgi aparatus
b) the gene that suppresses alpha-synuclein is missing or is not functioning properly in such yeast cells
c) drug therapy has proven to be ineffective in yeast cells
d) the normal distribution of proteins to the different cell components outside the Golgi apparatus will be affected
e) alpha-synuclein is by nature a toxic protein

[RonPurewal]

Hi All,

In the below question, OA = D....can someone please tell why not B ?

choice (b) stems from a misunderstanding of the question stem.

the question stem is
It can be inferred from the passage that a yeast cell with toxic levels of alpha-synuclein will die because...

this means that you're looking for the DIRECT CAUSE of cell death. that direct cause is the interruption of "the smooth transfer of proteins from the endoplasmic reticulum to the golgi apparatus" (cf end of second paragraph).
you're answering the question backwards - you're giving the reason why the cells discussed in the passage HAVE high levels of a-synuclein in the first place, rather than discussing why this will cause them to die.
moreover - and much more importantly - the phrasing of the question indicates that you have to pick an answer that applies to the death of ALL cells with toxic levels of a-synuclein, regardless of why the cells have those levels. choice (d) explains this correctly, per the passage, while choice (b) fails to do so.

--

this is perhaps most easily explained by analogy.

let's say a passage includes the following:
major industrial accidents can lead to injuries that cause massive hemorrhaging of blood. if not treated quickly, that hemorrhaging will lead to certain death by massive blood loss.

question prompt -->
It can be inferred from the passage that a person with massive hemorrhaging will die because...

choice (b) --> he/she was involved in a major industrial accident
choice (d) --> he/she will suffer massive blood loss

it should be clear why (b) is wrong and (d) is correct in this case.

this problem, while certainly more difficult, is structured in exactly the same way.

[tienvunguyen]

I do not understand this discrepancy.

Text: When the smooth transfer of proteins from the endoplasmic reticulum to the Golgi apparatus is interrupted, the cell dies.

Answer: d) the normal distribution of proteins to the different cell components outside the Golgi apparatus will be affected

The text clearly says 'transfer TO the Golgi' itself, not 'to DIFFERENT components outside the Golgi'. How can this be the right answer?

[tim]

Because the Golgi apparatus only sorts proteins before sending them where they are needed. The question is expecting you to make the connection that the Golgi apparatus is merely a conduit of proteins to the places where they are actually needed..

I do not understand this discrepancy.

Text: When the smooth transfer of proteins from the endoplasmic reticulum to the Golgi apparatus is interrupted, the cell dies.

Answer: d) the normal distribution of proteins to the different cell components outside the Golgi apparatus will be affected

The text clearly says 'transfer TO the Golgi' itself, not 'to DIFFERENT components outside the Golgi'. How can this be the right answer?

[rte.sushil]

a) low levels of dopamine will disrupt the flow of proteins from the endoplasmic reticulum to the Golgi aparatus

why A can't be the answer?
explanation says that: (A) According the second paragraph, "high levels of alpha-synuclein disrupt the flow of proteins from the endoplasmic reticulum...to the Golgi apparatus," not low levels of dopamine.

but this question is inferred based, so high levels of alpha-synuclein will reduce levels of dophamine ( Symptoms of Parkinson’s Disease, such as tremors, are thought to be caused by low dopamine levels in the brain---> so level is low when the parkisnson's disease is present and this will be low when alpha-synuclein is high because it will act as toxic for dophamine level which will be reduced )where i am wrong in inferring this? :(

please help!!

thanks!!!

[jlucero]

a) low levels of dopamine will disrupt the flow of proteins from the endoplasmic reticulum to the Golgi aparatus

why A can't be the answer?
explanation says that: (A) According the second paragraph, "high levels of alpha-synuclein disrupt the flow of proteins from the endoplasmic reticulum...to the Golgi apparatus," not low levels of dopamine.

but this question is inferred based, so high levels of alpha-synuclein will reduce levels of dophamine ( Symptoms of Parkinson’s Disease, such as tremors, are thought to be caused by low dopamine levels in the brain---> so level is low when the parkisnson's disease is present and this will be low when alpha-synuclein is high because it will act as toxic for dophamine level which will be reduced )where i am wrong in inferring this? :(

please help!!

thanks!!!

2 reasons:

1) because inference-based questions on the GMAT really just ask you to spit out what the text already said. don't read too much into anything and especially not into anything that's more than a sentence or two away from the topic at hand

2) because the questions asks- It can be inferred from the passage that a yeast cell with toxic levels of alpha-synuclein will die because...

The first paragraph isn't talking about yeast cells, it's talking about Parkinson's disease in humans. There seems to be a relationship between dopamine and alpha-synuclein proteins, but we don't know specifically know what that relationship is.

[nasheen_shaikh]

Hi Ron,

Below question is from same passage:
I don't have OA of these question,but i have chosen answer as 'D' is it correct?
Reason: Recent research provides insight into the inner workings of dopamine-producing neurons, and may lead to a new drug treatment that would proactively protect the neurons from decay.

old research may lead to new one.

But i was confuse about even in option 'C'

as it is stated that "Without a more detailed understanding of the behavior of dopamine- producing neurons, it has been impossible to develop treatments"

but doesn't mean dopamine producing neurons is neglected in previous study.
correct me if i am wrong
2. It can be inferred from the passage that current treatments of Parkinson’s Disease
A. repair damaged cells by replenishing dopamine levels
in the brain
B. are ineffective in their treatment of Parkinson’s symptoms, such as tremors
C. were developed without a complete understanding of dopamine-producing neurons
D. will inevitably be replaced by new drug therapy to
suppress alpha-synuclein toxicity
E. were not developed through research on yeast cells

[jlucero]

nasheen_shaikh, your logic is correct here and that's why C is correct. From that same sentence you quoted, how would you explain that you can infer answer choice D?

[JacobW468]

Bump question #2...

It can be inferred from the passage that current treatments of Parkinson’s Disease...

(a) repair damaged cells by replenishing dopamine levels in the brain

(b) are ineffective in their treatment of Parkinson’s symptoms, such as tremors

(c) were developed without a complete understanding of dopamine-producing neurons

(d) will inevitably be replaced by new drug therapy to suppress alpha-synuclein toxicity

(e) were not developed through research on yeast cells

I thought A, both times (during practice and review) but the answer is C. Can you provide more color on why "repaired damaged cells" is wrong and how I can avoid this mistake in the future?