Sweet Spot: Carbohydrates

>>Hello and welcome to
the Penguin Prof Channel. 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 video 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
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