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1. Read the following passage and then answer the questions that follow.
Anti-aging , by Mark A. Lane, Donald K. Ingram and George S. Roth
An abstract from Scientific American, Volume 287 Number 2, August 2002. P.26.
A. How can aging be delated ?
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To reduce the production of free radicals by the interruption of glucose processing and ATP
production may retard aging.
B. What is meant by “caloric-restriction mimetic”
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“Caloric-restriction mimetic” meant the situation similar to limiting the processing of glucose by
reducing the uptake of glucose by cells.
C. What would be the benefit of “caloric-restriction mimetic” over “caloric-restriction” ?
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“Caloric-restriction” is the situation in which the supply of glucose is limited. So, the processing
of glucose for the production of ATP is reduced.
Usually, this requires the reduction of eating.
“Caloric-restriction mimetic” is a situation that resembles the effect of “caloric-restriction”. Under
this situation, the subject has no need to reduce eating, but just to reduce the intake of glucose by
cells.
D. What chemical can be a “caloric-restriction mimetic” ?
Complete its structural formula in below.
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The chemical 2DG, 2-deoxy-D-glucose can be one of the caloric-restriction mimetic”. Its structural
formula is as follow.
E. One of the theoies explaining the triggering-on of anti-aging mechanism by the production of ATP.
Give a brief description for this hypothesis.
In the production of ATP,
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free radicals are emitted. These free radicals are thought to
contribute to aging and to such age-related diseases as cancer by damaging cells.
F. From the three diagrams in lower right corner, you can know how ATP is formed. From these
diagrams
(i)
Where do these reactions take place ?
Give evidence for your answer.
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These reactions take place in the inner membrane of the mitochondria. From the
diagram it is found that there are some proteins related to the production of ATP bound
inside the lipid bilayer structure. The bilayer structure represents the structure of the
membrane. It is shown in the diagram in above that the location of the membrane is in
the inside of the mitochondrion. So, ATP production occurs in the inner membrane of the
mitochondria.
(ii)
What are the type of materials involved in these reactions in related to their locations
and functions.
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The materisl involved in these reactions are respiratory enzymes or co-enzymes.
G. In the lower left corner, the 3 diagrams illustrate the processes of reactions.
(i) Which is the enzymatic reaction model using for explanation ?
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It is the lock and key hypothesis.
(ii) The last diagram illustrates a type of inhibition. What is the type of inhibition ?
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It is the competitive inhibition.
(iii) Describe the characteristic of this type of inhibition.
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The characteristic of the competitive inhibition is that it is a reversible reaction.
The
2DG competes with the glucose intermediate against the active site of enzyme 2. If plenty
of glucose or glucose intermediate is supplied, the inhibition can be minimized and the
reaction rate can be restored to the original level.
H. State the characteristics of enzymatic reactions.
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An enzymatic reaction is (1) specific. An enzyme can act on one substrate only. It gives no
reaction to other chemicals.
(2) The enzyme will involved in the reaction, but eventually, it would be released and the amount
will not decrease. It is reversible.
(3) Enzymes can shorten the time for teaching equilibrium of the chemical reaction, but not
increase the production of products.
I. Why this anti-aging method is not tested in human ?
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This anti-aging method is not tested in human because the chemical, 2DG is poisonous. – 0.5%
Discussion ---- 1%
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