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Green Fluorescent Protein (GFP) is a protein that emits bright light i

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Green Fluorescent Protein (GFP) is a protein that emits bright light i  [#permalink]

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New post Updated on: 28 Oct 2018, 20:15
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Green Fluorescent Protein (GFP) is a protein that emits bright light in the green segment of the visible spectrum upon exposure to blue light. Its properties were first researched in 1962 by Osamu Shimomura, a Japanese scientist who studied the bioluminescence of Crystal Jellyfish, or Aequorea victoria. Shimomura discovered that such biologically-generated glow is produced when the jellyfish produces calcium ions. The ionized calcium is absorbed by a protein that produces blue luminescence upon binding with calcium, called Aequorin. Crystal jellyfish typically have nodes of Aequorin on the rim of their umbrella, but Shimomura found that these photosensitive organs are composed of another type of protein. The blue light resulting from the Aequorin calcium binding is received by the protein now known as GFP. Since GFP's major excitation peak is at a wavelength of 395nm, or in other words - blue light, it becomes active and emits visible light whose peak is at 509nm, i.e., green light. This creates a circle of greenish light around the jellyfish's umbrella. Shimomura et al received a Nobel Prize in Chemistry for the discovery and development of GFP.

GFP has numerous uses in cellular and molecular biology, most commonly as a reporter of expression. In layman's terms, Green Fluorescent Protein is used as an indicator to the activation of certain genes into which it is spliced. This means that only the cells in which those specific genes are activated will fluoresce green under a blue light. This has been tremendously useful in mapping out the connection between DNA strings in genes and the biological systems which they control.

Another field where GFP was found to be profoundly useful is fluorescence microscopy. Before the discovery of GFP and its derivatives, fluorescent microscopists used synthetic fluorophores to dye the target sample. However, such fluorophores were found to be highly phototoxic, as the light they emitted was transferred to oxygen molecules in the cells under examination. This provoked the creation of oxygen radicals that could kill a living cell in seconds. GFP has proven to be dramatically less phototoxic, thereby revolutionizing this field of science.

1. The relationship between cells under examination in fluorescence microscopy and oxygen molecules is most similar to which of the following?

A. the relationship between human beings and the air they breathe
B. the relationship between the ecosystem and industrial pollution poisoning it
C. the relationship between a sovereign state in which the citizens are deliberating a revolt and those citizens
D. the relationship between a machine and a faulty cogwheel
E. the relationship between two enemy armies ready for war

Before we try to find the correct answer for this Application question, let's establish what the relationship mentioned in the question stem is. Our Initial Reading points us to the third paragraph, which deals with fluorescence microscopy. Regarding oxygen molecules, we read that the light ... emitted was transferred to oxygen molecules in the cells under examination. This provoked the creation of oxygen radicals that could kill a living cell in seconds. Therefore, we're looking for a relationship in which the second item (oxygen molecules appear second in the question stem) is a part of the first item (cells under examination). The second sentence tells us that the second item can destroy the first if it is somehow provoked. Answer C: The citizens are a part of the state, but may overthrow (destroy) it in a revolt if they are provoked.


2. The author refers to oxygen radicals in order to point out

A. the potential danger to human life when using a certain kind of fluorophore
B. that jellyfish can use their poison to introduce toxins to their victim's system
C. the reason for which GFP is no longer used in fluoresence microscopy
D. a negative effect that the use of GFP as an alternative dye in fluoresence microscopy has significantly reduced
E. the importance of GFP in the field of cellular biology

The sentence in which oxygen radicals are mentioned states that they can kill a living cell in seconds. The following sentence tells us that GFP has proven to be dramatically less phototoxic, i.e. much less dangerous to the cells under investigation. Answer D: GFP allows scientists to dye cells for examination under the microscope without the negative effect of killing them in seconds.


3. It can be inferred from the passage that Crystal Jellyfish

A. must have a constant supply of calcium to survive
B. have enough GFP to illuminate their way in the dark
C. do not require anything to spread a green glow
D. do not require an external blue light source to spread a green glow
E. use the circle of light on their umbrella to deter underwater predators

Answer D: In the first paragraph, Crystal Jellyfish are said to have nodes of Aequorin on the rim of their umbrella. In the next sentence, we read that the blue light resulting from the Aequorin calcium binding is received by the protein now known as GFP. This tells us the jellyfish do not need an external light source to glow green; they have the light source in their bodies, in the form of Aequorin.


4. Which of the following best describes the relation of the second paragraph to the passage as a whole?

A. It creates a logical connection between the first and third paragraphs.
B. It serves an an example of the theory presented in the first paragraph.
C. It presents a certain application, which is contrasted in the third paragraph.
D. It is the first of two paragraphs describing applications of the information presented in the first parargraph.
E. It repeats the technical information presented in the first paragraph in simpler terms.

Answer D: This answer choice tells it like it is - the second paragraph is the first of two paragraphs (the second is the third paragraph) that describe applications of information presented in the first paragraph, i.e., applications of GFP's unique properties.


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Originally posted by reto on 07 Sep 2015, 11:04.
Last edited by workout on 28 Oct 2018, 20:15, edited 2 times in total.
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Re: Green Fluorescent Protein (GFP) is a protein that emits bright light i  [#permalink]

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New post 08 Sep 2015, 02:20
Well, i have
D
D
D
D

and in even in GMAT Terms that seemed a bit too strange ;)

And in my opinion D fits better for question 1 than C. The second item (the faulty cogwheel) can destroy a machine within milliseconds should such a reaction be provoked (e.g. through bad maintenance etc.) Thats just my opinion, but D makes more sense in logical terms to me. Two armies ready for war can just as well be called off and nothing would happen...
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Re: Green Fluorescent Protein (GFP) is a protein that emits bright light i  [#permalink]

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New post 08 Sep 2015, 03:47
noTh1ng wrote:
Well, i have
D
D
D
D

and in even in GMAT Terms that seemed a bit too strange ;)

And in my opinion D fits better for question 1 than C. The second item (the faulty cogwheel) can destroy a machine within milliseconds should such a reaction be provoked (e.g. through bad maintenance etc.) Thats just my opinion, but D makes more sense in logical terms to me. Two armies ready for war can just as well be called off and nothing would happen...


Don't you think that you are assuming a bit too much with the faulty cogwheel? I am not a mechanic, but can a faulty cogwheel completly destroy a machine within seconds? The whole machine or just part of the machine? If it can make it disfunction, then it would not be the same... but otherwise who knows ... :)
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Re: Green Fluorescent Protein (GFP) is a protein that emits bright light i  [#permalink]

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New post 30 Oct 2018, 15:16
reto, workout, tarunanandani, honneeey
could you please spare some time and explain why D is the answer for Q2. I really didn't follow option D at all.

2. The author refers to oxygen radicals in order to point out

A. the potential danger to human life when using a certain kind of fluorophore
B. that jellyfish can use their poison to introduce toxins to their victim's system
C. the reason for which GFP is no longer used in fluoresence microscopy
D. a negative effect that the use of GFP as an alternative dye in fluoresence microscopy has significantly reduced
E. the importance of GFP in the field of cellular biology

I referred to the last para:
Another field where GFP was found to be profoundly useful is fluorescence microscopy. Before the discovery of GFP and its derivatives, fluorescent microscopists used synthetic fluorophores to dye the target sample. However, such fluorophores were found to be highly phototoxic, as the light they emitted was transferred to oxygen molecules in the cells under examination. This provoked the creation of oxygen radicals that could kill a living cell in seconds. GFP has proven to be dramatically less phototoxic, thereby revolutionizing this field of science.

My understanding: Author mentioned about another field where GFP is useful. Author says that before GFP was discovered, synthetic fluorophores was used to dye. this could cause problems kill the cell. The author concludes that GFP is less phototoxic.

Now, if we read the option D again,
D. a negative effect that the use of GFP as an alternative dye in fluoresence microscopy has significantly reduced

"A negative effet that the use of GFP as an alt dye" <-- This statement is not given in the para. It can't be inferred as well. Author clearly stated that before discovery of GFP, some alt dye was used. GFP itself was not used as a dye.

Hence i thought E is the right answer as author concludes -->GFP has proven to be dramatically less phototoxic, thereby revolutionizing this field of science
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Re: Green Fluorescent Protein (GFP) is a protein that emits bright light i  [#permalink]

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New post 30 Oct 2018, 20:16
Cinematiccuisine wrote:
reto, workout, tarunanandani, honneeey
could you please spare some time and explain why D is the answer for Q2. I really didn't follow option D at all.

2. The author refers to oxygen radicals in order to point out

A. the potential danger to human life when using a certain kind of fluorophore
B. that jellyfish can use their poison to introduce toxins to their victim's system
C. the reason for which GFP is no longer used in fluoresence microscopy
D. a negative effect that the use of GFP as an alternative dye in fluoresence microscopy has significantly reduced
E. the importance of GFP in the field of cellular biology

I referred to the last para:
Another field where GFP was found to be profoundly useful is fluorescence microscopy. Before the discovery of GFP and its derivatives, fluorescent microscopists used synthetic fluorophores to dye the target sample. However, such fluorophores were found to be highly phototoxic, as the light they emitted was transferred to oxygen molecules in the cells under examination. This provoked the creation of oxygen radicals that could kill a living cell in seconds. GFP has proven to be dramatically less phototoxic, thereby revolutionizing this field of science.

My understanding: Author mentioned about another field where GFP is useful. Author says that before GFP was discovered, synthetic fluorophores was used to dye. this could cause problems kill the cell. The author concludes that GFP is less phototoxic.

Now, if we read the option D again,
D. a negative effect that the use of GFP as an alternative dye in fluoresence microscopy has significantly reduced

"A negative effet that the use of GFP as an alt dye" <-- This statement is not given in the para. It can't be inferred as well. Author clearly stated that before discovery of GFP, some alt dye was used. GFP itself was not used as a dye.

Hence i thought E is the right answer as author concludes -->GFP has proven to be dramatically less phototoxic, thereby revolutionizing this field of science


Hi,

You yourself have pointed to option D!

See, Even if there was some other dye that was used before GFP, option D still holds Valid in stating that the negative effects(refer "This provoked the creation of oxygen radicals that could kill a living cell in seconds. ..") is corrected by use of GFP(which has dramatically reduced the probability of cells being killed in the process).

option E starts well but ends too high to be properly substantiated by the prompt!

Can we really say the use of GFP has revolutionized the field of science? Not Sure!(Revolutions were IC engine, PCs etc).

Moreover, mere use of GFP which author has himself/herself mentioned has dramatically reduced not eradicated the phototoxicity completely.

In comparison, Choice D is a tad bit better than choice E!

Hope it helps!
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Re: Green Fluorescent Protein (GFP) is a protein that emits bright light i  [#permalink]

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New post 17 Nov 2018, 23:03
Can experts( economist gmat) explain the Q1. it is very difficult for me to assimilate.


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Green Fluorescent Protein (GFP) is a protein that emits bright light i  [#permalink]

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New post 20 Nov 2018, 13:15
3
rinkumaa4 wrote:
Can experts( economist gmat) explain the Q1. it is very difficult for me to assimilate.
Regards


rinkumaa4 :
let me try. The para is difficult so let's separate out the info.

Q1. The relationship between cells under examination in fluorescence microscopy and oxygen molecules is most similar to which of the following?

Reference para : This question refers to para 3, here's the snippet.
Para 3:
Before the discovery of GFP and its derivatives, fluorescent microscopists used synthetic fluorophores to dye the target sample. However, such fluorophores were found to be highly phototoxic, as the light they emitted was transferred to oxygen molecules in the cells under examination. This provoked the creation of oxygen radicals that could kill a living cell in seconds.

how to interpret:
a) so essentially, Synthetic FP are phototoxic; The light emitted provoked / stirred creation of oxygen radicals --> thus could kill the cell.
b) As per paragraph, author uses words such as 'provoked', 'radicals' etc.
c) we can infer that the outcome is opposite --> rather than helping a cell, the reaction could kill the cell.
d) MOST IMP: The question is asking us to compare relationship between fluorescence microscopy ('cause') and oxygen molecules ('impacted object') due to 'oxygen radicals' (causing agent/byproduct).

So essentially, in the answer choices, we need to correlate similar logic. We need to find something that indicate an opposite behavior. Something that goes against the expected cooperation/ outcome.

now let's look at each of the choices:

A. the relationship between human beings and the air they breathe
Analysis : Not relevant choice
explanation: as i mentioned, we are looking for something that shows opposite behavior. Here, we simply understand human being and air. we don't know if we are comparing bad air / fresh air / good air. so this is not an option.

B. the relationship between the ecosystem and industrial pollution poisoning it
Analysis : Not relevant choice
explanation: This is the option that most of us including myself selected. Trickier choice!!
This choice compares ecosystem (impacted object) and industrial pollution (causing agent/byproduct), whereas, question is asking us to compare 'cause' and 'impacted object'. hence this is not a correct option.
If the option was comparing, ecosystem (impacted object)and Industries('cause'), then we could've thought further. The industries('cause') are producing pollution(causing agent/byproduct). There can be multiple interpretation, but this is the best i could think of.

C. the relationship between a sovereign state in which the citizens are deliberating a revolt and those citizens
Analysis : relevant choice
explanation:
I didn't know meaning of 'sovereign' state, but simply reading the word 'revolt', i could understand that this option shows a opposing action.

What essentially we can infer is, The citizens are going against the king/monarchy (sovereign) rather than going with the king. This can be related same way--> application of fluorescence should help oxygen molecules, but rather than that, it's killing the molecules/cell. hence this seems to be more logical and correct answer choice.

D. the relationship between a machine and a faulty cogwheel
Analysis : Not relevant choice
explanation: Again, this is not a correct comparison as option already shows a faulty cogwheel; doesn't related to 'cause' .

E. the relationship between two enemy armies ready for war
Analysis : Not relevant choice
explanation: we are not comparing two opposite sides here. Question compares 'cause' and 'impacted object'. hence this is not a correct option.

---
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Re: Green Fluorescent Protein (GFP) is a protein that emits bright light i  [#permalink]

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New post 25 Nov 2018, 07:08

Passage Map:


1) GFP. How is it formed?
2) Use of GFP
3) Another use of GFP
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Re: Green Fluorescent Protein (GFP) is a protein that emits bright light i &nbs [#permalink] 25 Nov 2018, 07:08
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