Sweet Spot: Carbohydrates
>> Hello and in today’s episode I want to talk about one of the macromolecules of life, carbohydrates. So let’s get eating. If you go to the grocery store you’re going to see lots of examples of carbohydrates. This tutorial is going to explore the biology, some chemistry and some nutritional aspects of this really important group. We use carbohydrates for short-term energy storage. These carbohydrates actually have to be converted into ATP, which is what your cells actually use to do work. But carbohydrates are really the source of most of that ATP. We use carbs for long-term energy storage, and we also build a lot of things. We use them for structural components. You’ll see some examples of that in a little bit. Carbohydrate literally means hydrated carbon. These molecules have a ratio of carbon to hydrogen to oxygen is 1 to 2 to 1. You’re going to see o-s-e as a suffix in describing and naming carbohydrates.
And some examples, if you’ve got 5 carbons in your carbohydrate, we call that a pentose. Six carbons we call a hexose. If the carbonyl carbon has an aldehyde on it, we call it an aldose. And if the carbonyl carbon has a ketone on it, we call it a ketose. So just so you can recognize some of these terms when you see them. So let’s look at some carbohydrates. We’re going to start with the monosaccharides. Mono means one, and saccharide is Greek for sugar. These are single chains either five or six carbons long. This is glucose. This monosaccharide is the fuel for life. This is really what your cells are burning so that your body can do all the amazing things that it does. This is what our fuel molecule really looks like. Now, if you take two monosaccharides and you join them together in a reaction call dehydration synthesis, you get a disaccharide. Di just means two, and sucrose is what you know as table sugar. Another disaccharide you know is if you take two glucose monomers, two glucose monosaccharides and you join them together in a particular way you get maltose or malt sugar, which you know from beer.
Another disaccharide is lactose or milk sugar. Now, oligosaccharides, that term comes from the Greek meaning few or a little. Well, that’s about 3 to 10 monosaccharides linked together. If you link individual oligosaccharides together, you can make a polysaccharide. Poly means many. Some oligosaccharides react with lipids to make lipopolysaccharides. Some of them react with sides chains of amino acids especially asparagine — there it is — to form a glycoprotein. Glycoproteins turn out to be really important and they’re all over the place. One example of a glycoprotein, one of my favorites is the family of Mucins because I love mucous. Mucus is life’s lubricant. We use them in the mucosa epithelium. It turns out that the sugars attached to the protein gives the molecule a really good ability to soak up and hold water kind of like a sponge, and they can form basically molecules that behave a lot like your hair gel and that makes them really useful for things like will you be lubrication, chemical barriers, and other stuff, too.
Here’s a really important molecule called Mucin 1. And nacre formation in molluscs, that mother of pearl happens because of mucins. Echinoderms can make their endoskeleton with the help of mucins. Mucins also control some of our bone formation. So it’s important for bones, also for part of the immune system response. And it turns out we’re finding that you if you over express or you change the way that the carbohydrates attached to mucins you can have problems. And we see this in many types cancer. So Mucins and other glycoproteins really important. If you have many individual monosaccharides joined together you make a polysaccharides.
And poly just means many. And nutritionally we’re talking about grains and all kinds of relatives of grains. This is kind of a neat image. These are all chains of glucose, but they’re all linked together in different ways. And turns out that some of them we can digest, we can break these bonds and use them for energy, and some we can’t. Starch is a go. We have then enzyme that breaks down the bonds between the glucose units, and we can break down starch and use the glucose for energy. We can use glycogen. We can break those bonds, too. But cellulose, cellulose, we can’t. We cannot break the bonds between the glucose subunits and use cellulose for energy. We call it fiber. So where we get carbohydrates in the diet you probably know. Monosaccharides come from fruits and berries and honey. Disaccharides, you got table sugar, cane sugar, milk, some other fruits. Starch polysaccharides, we got cereals and whole grains and pasta. Non-starch polysaccharides, we’re talking about the cellulose in the leafy greens’ cell walls. We don’t get energy out of that, but as you know dietary fiber is really important for the diet.
It’s good for your colon. We get vitamins and minerals and all kinds of good stuff, but we just don’t get the energy. The naturally occurring sugars are really important, and they’re part of a healthy diet. The nutritional concern is added sugar that we find in processed foods and beverages. Now, the American Heart Association recommends these maxima for men, women and children. This is, again, added sugar. Not the sugar found in your normal, healthy diet when you eat fruits and vegetables and whole grains and all that. This is added sugar, ok. These are the maxima. But the average American eats — are you ready for this? — 22 teaspoons of added sugar every day. Now, if you want to know what that looks like. Oh my goodness. That’s a lot of sugar. That is an insane amount of sugar, people. That is insane. You’ve probably heard about the glycemic index, people saying, well, not all carbohydrates are the same in the body and that’s true. The glycemic index measures how blood glucose levels change after you ingest different types of carbohydrates.
So the idea is that foods that quickly digest and immediately release glucose into the blood, they have a high glycemic index. You can also look at the insulin index. This is a related value and that just measures the response of insulin secretion to different carbohydrates. So here’s the idea. Glycemic index range 55 or less we consider a low value and that’s good. What that means is that these foods when you ingest them they increase your satiety so you’ll feel satisfied, but they very, very slowly release glucose into the blood. So the idea is you don’t get this big glucose rush. Medium glycemic index kind of in the middle. The high glycemic index, that’s really the very highly processed grains, the really sugary breakfast cereals.
When you eat those foods, you get a really big sugar rush, and that’s what you want to avoid. So when you are eating carbohydrates, the lower the glycemic index, the healthier. Hopefully you learned something new about carbohydrates today. As always, thank you for visiting the Penguin Prof Channel. Please support by clicking like, share, and subscribe. Join us on Facebook, follow on Twitter. Good luck..
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