laymans terms- simplified or easier to explain. Ie I don’t want to get into too much depth because my understanding is minimal, and I’m not a biology studen but rather a psychology student who has taken an extra biology module to better understand the bodies physiology.

I have to give a presentation on friday explaining the digestive system however, and although I have now developed a reasonable understanding on most of the digestive system, the more I read on enzymes the more I confuse myself.

For example carbohydrates are divided into 3 groups- disaccharides, monosaccharides, polysaccharides. I’m reading the aim is to break disaccharides and polysaccharides into monosaccharides, but that confuses me as I’m also reading that carbs, ie starch, need to be broken down into maltose. But maltose is a result of a substrate, whereas monosaccharides are a substrate- so how can a substrate (monosacharides) be brokwn down into…well, monosaccharides?? Does that make sense? And am I understanding it all wrong?

What do you mean my examples do now belong in one row? I’m trying to make the table from scrach based on my readings and understandings, but can’t quite formulate the basic (emphasis on basic here!) table categories I need.

See this is where I get confused. My understanding is that peptides (sorry typo in first post!) are the result of a substrate being broken down by an enzyme, but polysaccharides etc are actual substrates?

Ha this is like trying to grab smoke with my hands at the moment. Just as I think I am beginning to understand it it slips through my fingers!

I understand pepsin has nothing to do with saccharides, as they are a group of carbs- right? Pepsin is an enzyme that breaks up protein, where as amaylase breaks up carbs- ie dissacharides and polysaccharides etc?

Ok if I approach it like this:
Location: Mouth. Enzyme: Amylase: Substrate: carbs- mainly starch (Disaccharides and
Polysaccharides??): Result: maltose (and monosaccharides???)

Is that right?

Location: Stomach. Enzyme: Pepsin: Substrate: Protein Result: polypeptide?

Also I understand the enzyme Pepsin belongs to the peptidase group of enzymes, so is there a group that amylase belongs to? Or is amylase the group, and in actual fact the specific enzymes have other names?

And by the way- I really, really appreciate all the help as I can appreciate how hard this muct be to explain to someone who has no clue!

Ah right ok, it’s starting to make sense.

Ok would I be right in saying that in the stomach, the enzyme Pepsin (belonging to the enzyme group peptidase) breaks down the substrate protein into peptides. These then pass into the duodenum where the peptides now become the substrate? So the amylase trypsin (enzyme group hydrolases??) in the s.intestine breaks down the substrate peptides into…something…?

Ok that actually all made sense. I think maybe I am trying to be too reductionist and group it all into an easy to read table consisting of set categories, like enzyme, substrate, result etc when really it doesn’t quite work like that. (unfortunately!) Or at least it does but there are so many enzymes etc and substrates that it is a pointless task.

I understand amylase doesn’t work on proteins, as I see enzymes working like jigsaw pieces in that they only fit certain shaped/sized substrate molecules, so the substrate for amylase is carbs.

But you’re right, all the terminologies confused me. I saw monosaccharides, disaccharides and polysaccharides etc as simply being different types of starch that needed to be broken down into maltose. But it’s not- starch is a polysaccharide, a type of carbohydrate. Maltose is a disaccharide. So both maltose and strach effectively need to be broken down into a monosaccharide?

Can a polysaccharide be broken down straight to a monosaccharide? Or does it have to be broken down to a disaccharide, then a monosaccharide? and if so am I right in saying if starch enters the mouth, it is broken down into maltose first? Or is that just a massive generalisation, and not necessarily true?

So amylase breaks polysaccharides into disaccharides in the mouth. This disaccharide (in the form of maltose) travles through to the small intestine where maltese breaks the disaccharide into monosaccharide (glucose)?

Do you know how disaccharides reach the small intestine? I assume it isn’t through the alimantary canal?(though I could be wrong!)

Ahh polypeptides that does actually sort of answer another question I had- are polypeptides broken down into peptides? And then into amino acids? Or are polypeptides and peptides in reality the same thing? Are there ‘dipeptides’? Or have I just made that word up?

I’m going to be honest, much of that wiki link is lost on me. I understand the very basics of enzyme breakdowns, but when you start going into ‘Glc’ and the such I get lost. I’m not really a biology student, I’m just taking a sort of biology for beginners module at uni to better understand the biological side of my psychology degree! fortunately I’m not quite as inept when it comes to psychology…!

Ha my name comes from a skateboarder named Chad Muska. When I was younger I used to skate and had Chad Muska’s siganture deck, so a few people started calling me Muska and it kind of stuck ever since.

Ok I now understand what you all have been trying to explain to me for the last 2 days. (By understand I mean understand on a very basic level!) But I have managed to put it into my powerpoint presentation- huzzah! And better, I know what enzymes are for and what saccharides etc are so hopefully I won’t get caught out by the tutor! (A week ago I had never even heard of an enzyme, nevermind polypeptides and disaccharides etc!)

Honest to God if I hadn’t have come here I would still be buried neck deep in biology books trying to get my head around the whole concept (although if I had really thought about it- the clues are in the names poly/di/mono etc.) so I owe everyone who has offered me advice here massively. I really do.

Kudos for keeping patient with me as I fumbled my way around molecular biology 101 though, really is much appreciated.