Nbme form 5 :Biochem question

[winston]

1 hour after eating a potato what parameter will be increased?

a) glucose
b) amylose
c) limit dextran
d) pectin
e) sucrose

[mona_zahiri]

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[beefy]

1 hour after eating a potato what parameter will be increased?

a) glucose
b) amylose
c) limit dextran
d) pectin
e) sucrose

i choose answer C

starch is ~25% amylose, ~75% amylopectin

alpha-amylase (dextrinogenic amylase) breaks down amylopectin into small dextrins, limit dextran = end products at which another enzyme must take over to continue the breakdown.. and an hour later, i don't think you'd be at that point

i could be thinking about it too much, but i dont think any nbme is a "joke"

[winston]

Sometimes questions seem really easy and then when you think about it can get a bit tricky. The "one hour" parameter made me a bit unsure so I posted it.....There was also quite a bit of physiology on the form...lots of graphs and arrows if you know what i mean.....

[cooolguy]

so whats the answer?

[Future MD | DM erutuF]

I put A (glucose) because the brush border enzymes degrade dissacharides and only monosaccharides like glucose are absorbed. I don't believe any limit dextrans would be in the blood unless defective glycogenolysis is present (like in a glycogen storage disease), and glycogenolysis is not likely to be taking place at this point.

[cooolguy]

I agree with the above poster, you will not have amylose and amylopectin in your bloodstream. They may be found in the small intestine or so but they are not directly absorbed into the blood stream.

[leenas]

I also took the new NBME form 5 ...I scored a 440 , How much did u score Winston?

I choose C too.

[restless4success]

i think its A-

[sai213]

I think its A, but it could be C coz of the 1 hour thing. Potato is carbs they building blocks of glucose. During well fed state they converted into glycogen. Someone correct me if im going the wrong way.

[sai213]

here's another thing i forgot about insulin would have kincked in by then and it would have normalized the glucose level in the bld. So would you see glucose in the bld?

[terren shadow]

i pick A cause when the body metabolizes these "potatos" it must go to its simplest form first glucose... i would think it would take a bit longer for it to be stored in the liver in the form of glycogen even in well fed state... it must always form glucose first in order to be metabolized into something else... is my thinking right or do i need to review carbohydrate metabolism all over again...

[sai213]

Sometimes the simplest answer can be right the one.