Bio Achiever Question

[vindicate]

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Question went something like:

Which of the following is not exist in the small intestine?
A) fructase
B) nuclease
C) pepsin
D) maltase
E) aminopeptidase

I knew A, D, E are there.
nuclease at the time didn't register to me.
I knew pepsin is released by chief cells of gastric glands of stomach and exist only in low pH environment of stomach. I assumed as chyme goes into SI, for a brief period, as acidity of bile triggers pancreas to release HCO3-, pepsin exists there.

So I chose B. Apparently though, nuclease exists there, but I can't recall every reading about it in digestion. Afterward, I realized that Ecoli in SI might have nuclease.

 

[vindicate]

2) Another question as it relates to digestion:

Can humans digest chitin?

I figured we could eat mushrooms, so I assumed yes. Why not?
​

 

[Avery07]

My answer is C but I'm not sure if that is correct or not? I just don't see pepsin existing in the small intestine. Doesn't make much fundamental sense to me.

As for the nuclease.. why I think that is in the small intestine is that is it not everywhere? I would assume nuclease to exist wherever DNA exists and given this.. nuclease is all over the freaking place.

Maybe I'm wrong?

 

[BossOfFloss]

From what I remember, humans do not have the necessary enzyme to digest chitin. I'm almost positive it becuase chitin is made from Beta 1,4 linkages and humans can digest Alpha 1,4 glycosidic linkages

 

[Troyvdg]

From what I remember, humans do not have the necessary enzyme to digest chitin. I'm almost positive it becuase chitin is made from Beta 1,4 linkages and humans can digest Alpha 1,4 glycosidic linkages

yessir 👍

 

[vindicate]

How can we eat fungus then (e.g. mushrooms)?

Is it a bacteria in the gut that digests it for us (somewhat similar to lactose cataclysm in people with lactose intolerance?)

 

[sfoksn]

When they ask for substances that exist in the small intestine, it is asking for substances that will be present throughout the small intestine. I guess pepsin would be present in small amount in the entrance of duodenum, but nothing more than that.

 

[UndergradGuy7]

A) fructase
B) nuclease
C) pepsin
D) maltase
E) aminopeptidase

Small intestine has stuff to break down carbs, proteins, nucleic acids, and fats.

So fructase, maltase, aminopeptidase should be known right away. Nuclease breaks down nucleic acids and is also there. Also know lacteals are there to absorb fats. Pepsin is made in the stomach and not in the small intestine and works in the acidic conditions of the stomach. Once it gets to the small intestine it is denatured because the pH becomes basic. Inactive form of pepsin = pepsinogen right? So its not pepsin.

 

[vindicate]

A) fructase
B) nuclease
C) pepsin
D) maltase
E) aminopeptidase

Small intestine has stuff to break down carbs, proteins, nucleic acids, and fats.

So fructase, maltase, aminopeptidase should be known right away. Nuclease breaks down nucleic acids and is also there. Also know lacteals are there to absorb fats. Pepsin is made in the stomach and not in the small intestine and works in the acidic conditions of the stomach. Once it gets to the small intestine it is denatured because the pH becomes basic. Inactive form of pepsin = pepsinogen right? So its not pepsin.

yeah, but SI releases secretin in response to acidity of chyme.
pepsin becomes pepsinogen after pancreas releases bicarb

so until bicarb reaches the SI, there is pepsin in the SI.

 

[jirotrom]

pretty sure the pancreas releases nucleases