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# Lysosomal storage diseases form a category of genetic disorders result

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Intern
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03 Oct 2015, 15:26
Hi,

About question 2. The explanation to the question states that A, B, D and E are out because it refers to "Tay-Sachs disease" and not to "lysosomal storage diseases" in general.

The thing is that to infer answer C you also need information about the "Tay-Sachs disease". As the answer asserts "C can be inferred from combining two statements in the passage: paragraph 3, which states that “those in the infantile category had little to no normal activity” and paragraph 2, which states that “children [with the infantile form of the disease] rarely live beyond 3 years old.” "Little... activity," while low, is still not zero activity." Hence, I am completely lost because, in fact, no of the answer referse specifically to "lysosomal storage diseases".

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20 May 2016, 11:59
I had this passage on my practice exam today and answered all questions correctly except for # 2.

I honestly still don't understand why the right answer is C.

These are the official answer explanations from Manhattan:

A) This choice states that it can be inferred that lysosomal storage diseases "are generally caused by mutations to the hexosaminidase gene." The passage only states that mutations in this gene are responsible for Tay-Sachs disease. There is no information suggesting that it is responsible for the entire class of storage diseases.

(B) This choice states that it can be inferred that lysosomal storage diseases "are undetectable until physical symptoms are present." The passage, however, discusses some specific genetic mutations that are linked to Tay Sachs diseases, a type of lysosomal storage disease. This indicates, if anything, that the disease might be detectable before physical symptoms are present.

(C) CORRECT. This choice states that it can be inferred that lysosomal storage diseases "can be fatal even when allowing some enzymatic activity." This can be inferred from combining two statements in the passage: paragraph 3, which states that “those in the infantile category had little to no normal activity” and paragraph 2, which states that “children [with the infantile form of the disease] rarely live beyond 3 years old.” "Little... activity," while low, is still not zero activity.

(D) This choice states that it can be inferred that lysosomal storage diseases "are most lethal when onset is in a patient's infancy." The information in the passage relating to infant mortality is given in the specific context of Tay-Sachs disease. We cannot know whether this pattern holds true for other diseases of this type. In addition, while those with the infantile form do die of the disease, so do those with the juvenile form, making the disease equally lethal.

(E) Choice E states that it can be inferred that the causes of lysosomal storage diseases were unknown before the 1950s. The passage states, however, that the causes of Tay-Sachs disease were unknown before that time. We do not have any information about the causes of lysosomal storage diseases generally.

Okay so all these answer choices except for C were wrong because they were taken from the Tay-Sachs passage which is only one type of lysosomal storage disease.

HOWEVER.... answer choice C ALSO takes information from the paragraph about Tay Sachs disease and applies it to the answer about lysosomal disease in general. So what the what????? I don't get it. The lines referred to in answer choice C refer to Tay Sachs disease.

Does anyone understand why C is correct and the other answer choices are not because they supposedly only talk about Tay Sachs disease?
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20 May 2016, 12:02
Funny.... that's exactly what I just wrote in my post under yours. I guess no one has a good explanation to this interesting "phenomenon".

Is parker still an active Manhattan instructor on this forum? Maybe he/she can explain this?

bolasao wrote:
Hi,

About question 2. The explanation to the question states that A, B, D and E are out because it refers to "Tay-Sachs disease" and not to "lysosomal storage diseases" in general.

The thing is that to infer answer C you also need information about the "Tay-Sachs disease". As the answer asserts "C can be inferred from combining two statements in the passage: paragraph 3, which states that “those in the infantile category had little to no normal activity” and paragraph 2, which states that “children [with the infantile form of the disease] rarely live beyond 3 years old.” "Little... activity," while low, is still not zero activity." Hence, I am completely lost because, in fact, no of the answer referse specifically to "lysosomal storage diseases".

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25 May 2016, 03:13
Tough passage, I got only #3 right in 8mins
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25 May 2016, 03:30
Silviax wrote:
Funny.... that's exactly what I just wrote in my post under yours. I guess no one has a good explanation to this interesting "phenomenon".

Is parker still an active Manhattan instructor on this forum? Maybe he/she can explain this?

bolasao wrote:
Hi,

About question 2. The explanation to the question states that A, B, D and E are out because it refers to "Tay-Sachs disease" and not to "lysosomal storage diseases" in general.

The thing is that to infer answer C you also need information about the "Tay-Sachs disease". As the answer asserts "C can be inferred from combining two statements in the passage: paragraph 3, which states that “those in the infantile category had little to no normal activity” and paragraph 2, which states that “children [with the infantile form of the disease] rarely live beyond 3 years old.” "Little... activity," while low, is still not zero activity." Hence, I am completely lost because, in fact, no of the answer referse specifically to "lysosomal storage diseases".

Let me try to exchange the idea by my own understanding after re-read the passage several time.

Sentence 6-11 said:

"When any one of the lysosomal enzymes is defective, the molecules requiring that specific enzyme for their degradation will accumulate and cause that individual's lysosomes to swell enormously. The physiological effects of such swelling on the individual include motor and mental deterioration, often to the point of premature death."

So the line of reasoning is that:

Any (>=1) LE failed --> swell enormously --> physiological effects...premature death: sound pretty serious and fatal to me!

C. They can be fatal even when allowing some enzymatic activity.

Up to this point, it becomes very tricky because "These enzymes do their work in the lysosome" and you only get issue "When any one of the lysosomal enzymes is defective"

But how do you define "some enzymatic activity" in this sense - since all the rest of the passages are only presented about TSD (not fully cover LSD), the best of my guest is that some enzymatic activity also includes the defective enzyme's work/activity as well.

Here is when the word "C. They can be fatal " is played its role here.

Voila, so there is a possibility that (by the word: CAN) enzyme is defective and is active --> fatal.

Therefore, C - is the best choice out of 5.
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Re: Lysosomal storage diseases form a category of genetic disorders result  [#permalink]

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09 Jun 2016, 00:35
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~11 mins. Got all correct but tricked by last one.
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17 Aug 2016, 05:01
sikalvag wrote:
answer for the second question is 'C' i got it from other forums
Explanation is (C) CORRECT. This choice states that it can be inferred that lysosomal storage diseases "can be fatal even when allowing some enzymatic activity." This can be inferred from the fact that people suffering from juvenile Tay-Sachs have "extremely crippled hexosaminidase activity" (lines 91-93) and generally live to only 15 years of age (line 49).

But its specifically valid for Tay-Sachs disease not all lysosomal storage diseases???
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02 Sep 2016, 11:53
Long , dense and very difficult
Got second incorrect , took around 10 mins
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24 Oct 2016, 18:21
Got all wrong..

What is the difficultly level of the passage.

kapsdeep wrote:
Lysosomal storage diseases form a category of genetic disorders resulting from defective enzymes that normally function to degrade unneeded molecules in cells. These enzymes do their work in the lysosome, a small compartment in a cell analogous to a garbage disposal. The lysosome contains between thirty and forty different degradative enzymes. When any one of the lysosomal enzymes is defective, the molecules requiring that specific enzyme for their degradation will accumulate and cause that individual's lysosomes to swell enormously. The physiological effects of such swelling on the individual include motor and mental deterioration, often to the point of premature death. But each disease resulting from one specific defective lysosomal enzyme has its own characteristic pathology. The age of onset, rate of progression, and severity of the clinical symptoms observed in patients with the same defective lysosomal enzyme are highly variable. For many years, this variability in patients with the same defective enzyme puzzled scientists. Only recently have researchers begun to answer the riddle, thanks to a genetic analysis of a lysosomal storage disorder known as Tay-Sachs disease.

As in most lysosomal storage diseases, patients suffering from Tay-Sachs disease show both mental and motor deterioration and variability in age of onset, progression, and severity. Physicians have categorized the patients into three groups: infantile, juvenile, and adult, based on onset of the disease. The infantile group begins to show neurodegeneration as early as six months of age. The disease advances rapidly and children rarely live beyond 3 years old. The first symptoms of the disease appear in juvenile cases between 2 and 5 years of age, with death usually occurring around age 15. Those with the adult form generally live out a normal lifespan, suffering from milder symptoms than do those with the infantile and juvenile forms. Researchers hoped that the categorization would yield insight into the cause of the variability of symptoms among Tay-Sachs patients, but this turned out not to be the case.

In Tay-Sachs disease, undegraded materials accumulate mainly in the lysosomes in the brains of patients, but the kinds of molecules left undegraded and the specific identity of the defective lysosomal enzyme responsible for the malfunction were not discovered until the 1950s and 60s, respectively. The main storage molecule was found to be a lipid-like material known as GM2 ganglioside. The defective enzyme was later identified as hexosaminidase. In 1985, the gene coding for the normal hexosaminidase enzyme was cloned and its DNA sequence determined. Shortly thereafter, the DNA sequences of genes encoding hexosaminidase from many Tay-Sachs patients were studied. It soon became apparent that not one or two but many different types of mutations in the hexosaminidase gene could result in Tay-Sachs disease. Some of the mutations prevented the synthesis of any hexosaminidase, preventing all such enzyme activity in the cell. Patients with this type of mutation all had the infantile form of Tay-Sachs disease. Other mutations were found in certain regions of the gene coding for areas of the enzyme known to be critical for its catalytic activity. Such mutations would allow for only extremely crippled hexosaminidase activity. Most of the patients with these mutations clustered in the juvenile category. Adult Tay-Sachs patients presented mutations in the regions of the hexosaminidase gene that were less important for the enzyme's activity than were those affected in juvenile patients. Scientists quickly hypothesized that the variation in age of onset and severity of Tay-Sachs disease correlated with the amount of residual enzymatic activity allowed by the genetic mutation. Though more research is needed to demonstrate similarity with other lysosomal storage diseases, the work done on Tay-Sachs disease has already offered a promising glimpse into the underlying mechanisms of these disorders.
Q1:
The passage suggests that which of the following lines of inquiry would be most useful in determining the relevance of the research done on Tay-Sachs disease to lysosomal storage diseases generally?
A. Do patients suffering from other lysosomal storage diseases have the same mortality rate as those suffering from Tay-Sachs?
B. Do other lysosomal storage diseases affect the hexosaminidase gene?
C. How many different mutations are present in the defective genes responsible for other lysosomal storage diseases?
D. Does the onset of other lysosomal storage diseases vary with the location of mutations in DNA sequences?
E. What purpose does GM2 ganglioside serve in the human body?

Q2:
It can be inferred from the passage that which of the following statements is true of lysosomal storage diseases?
A. They are generally caused by mutations to the hexosaminidase gene.
B. They are undetectable until physical symptoms are present.
C. They can be fatal even when allowing some enzymatic activity.
D. They are most lethal when onset is in a patient's infancy.
E. Their causes were unknown before the 1950s.

Q3:
The author of the passage is primarily concerned with
A. illuminating the physiological consequences of Tay-Sachs disease
B. explaining the importance of research on a specific disease to other diseases of that type
C. arguing for a more detailed examination of lysosomal storage diseases
D. challenging a traditional view of a class of diseases as incomplete
E. describing the implications of genetic mutations for mortality rates

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23 Dec 2016, 07:58
Is there any way how I can solve this paragraph as a Non-nativ speaker?
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20 May 2018, 23:06
It took me aruond 11 minutes to figure out answers with choices 1. C(I know its incorrect)2. C 3. B, However, my question is how to efficiently tackle such a paragraph on timely basis?
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22 May 2018, 17:42
It took me more than 10 minutes but got only 1 question correct and 2 wrong. This is one tough passage
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23 May 2018, 03:45
OMG!!

Such a tough passage
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19 Dec 2018, 06:34
parker wrote:
Oh my goodness, I'm so sorry I just saw that I hadn't replied to this! You may have already taken your test but just in case--

1. Yes, I absolutely write notes. There's way too much information to hold in my brain, so I make a structural map of the passage as I go along-- we teach something called the "skeletal sketch" in classes; this method focuses on comprehending much of the first paragraph and only the gist of the second. Within that technique there is a still a spectrum of how much/little people write for their own comfort levels--I tend to read pretty quickly but need to stay active to not have my attention wander, so I may write a little more than others. The important thing is to avoid getting bogged down in details during the entire passage-- comprehending every single thing is not your goal (it would take waaay to long and probably not yield you many points. The heavy detail work is for (1) when you're reading the beginning of the passage to get the gist and (2) when you go back to the passage while answering specific questions).

2. The answer to your second question is related to the answer to your first-- do NOT try to comprehend everything-- there's not enough time, so don't stress out if you don't grasp every little detail. Structure and main point are your goals for the first read. The little details can be dealt with if (and only if!) you're asked about them in the questions--you get points for correct answers, not for total comprehension

Hi! I would like to understand your technique ("skeletal sketch") . In your case, I understand that you read the first paragraph and then read the second to know the gist of the text. What about the other paragraphs?

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04 Jan 2019, 02:00
The answer to question number 2 seems more clearer in D.
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22 Jun 2019, 02:57
Tough passage:

Can anyone explain the option choice D in question 1

workout carcass

(D) Does the onset of other lysosomal storage diseases vary with the location of mutations in DNA sequences?

I just didnt mark this because of the word location.It is not dependent on location where the mutation is taking place but on the mutations themselves.

Can some one please clarify this.

Regards
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22 Jun 2019, 07:41
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Quote:
Some of the mutations prevented the synthesis of any hexosaminidase, preventing all such enzyme activity in the cell. Patients with this type of mutation all had the infantile form of Tay-Sachs disease.Other mutations were found in certain regions of the gene coding for areas of the enzyme known to be critical for its catalytic activity. Such mutations would allow for only extremely crippled hexosaminidase activity. Most of the patients with these mutations clustered in the juvenile category. Adult Tay-Sachs patients presented mutations in the regions of the hexosaminidase gene that were less important for the enzyme's activity than were those affected in juvenile patients. Scientists quickly hypothesized that the variation in age of onset and severity of Tay-Sachs disease correlated with the amount of residual enzymatic activity allowed by the genetic mutation.

Hope is clear now why is D. It is a related chain.

Regards
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