Give the name of one or more polysaccharides that matches each of the following descriptions:
(a) not digestible by humans

Question

Give the name of one or more polysaccharides that matches each of the following descriptions:

(a) not digestible by humans

Accepted Answer

All right. Hello everyone. So this question is asking us which of the following best explains why some polysaccharides are non digestible by humans. And here we have four different answer choices labeled A through D which we'll discuss later on in this video. But for now, lets go ahead and give some context to what the question is referring to. Now recall that this particular question is referring to what's known as dietary fiber. Dietary fiber is another way of referring to non digestible polysaccharides. So complex carbohydrates that we as humans cannot break down. So why can't we break it down? Well, the reason why we're not able to break down the polysaccharides referred to as dietary fiber is because humans simply lack the enzymes needed to digest them. And so because we're talking about polysaccharides, what we lack as humans are the enzymes necessary to break some of these glyco cytic linkages making up these complex carbohydrates. So basically, these cannot be broken down into monosaccharide. So examples of non digestible polysaccharides include, for example, cellulose which is found in the plant walls or cell walls of plants and also certain types of hemic cellulose. Now, what's interesting is that even though we as humans cannot digest and absorb these complex carbohydrates, they still play a role in promoting our health. So now let's look at these answer choices starting off with option A which says that they contain beta 14 glyco cytic bonds, which humans lack the enzymes to break down. This is actually true, right? Because polysaccharides like cellulose have characteristic beta 14 glyco cytic bonds between its glucose monitors because humans don't have the enzyme cellulose. These bonds cannot be broken down, which means that cellulose cannot be digested. Now, option B says they are too large to be absorbed through the intestinal wall. Now, the reason why Option B is incorrect is because even though these complex carbohydrates are indeed large molecules, that's not the reason why they cannot be absorbed. Now recall that the intestinal wall can only absorb monosaccharide. So, carbohydrates, polysaccharides that can be absorbed are polysaccharides that can be broken down into their monosaccharide units because these particular poly saccharide cannot be broken down into their monosaccharide units. That's why they cannot be digested. Not because they're too big. Option C says they have a highly branch structure which that prevents enzyme access and C is also incorrect because while it's true for these complex carbohydrates, they don't necessarily prevent enzyme access because glycogen, for example, is a complex carbohydrate that does have a branch structure but can still be broken down into monosaccharide units for digestion So really the problem here is the type of bond present which cannot be broken, not necessarily the branching that determines whether or not it can be digested. And last but not least option D says they are composed of monosaccharide that are not found in human digestive enzymes. Now, this is not correct because as mentioned before, it's monosaccharide that actually can be digested by our intestinal walls. The problem here is that these polysaccharides have specific chemical bonds, specific glyco cytic linkages, which we do not have the appropriate enzymes to break down. So there you have it once again, our correct answer is going to be option a in the multiple choice. And so with that being said, thank you so very much for watching and I hope you found this helpful.

Give the name of one or more polysaccharides that matches each of the following descriptions:
(a) not digestible by humans

Verified video answer for a similar problem:

Key Concepts

Polysaccharides

Digestibility

Cellulose

Give the name of one or more polysaccharides that matches each of the following descriptions:(a) not digestible by humans

Verified video answer for a similar problem:

Key Concepts

Polysaccharides

Digestibility

Cellulose

Give the name of one or more polysaccharides that matches each of the following descriptions:
(a) not digestible by humans