Carbohydrates | Biochemistry
Summary
TLDRIn this video, Dr. Mike discusses carbohydrates, one of the four major macromolecules, alongside proteins, fats, and nucleic acids. He explains that carbohydrates are composed of carbon, hydrogen, and oxygen, and exist in various forms: monosaccharides, disaccharides, and polysaccharides. Glucose, fructose, and galactose are common monosaccharides with the same chemical formula but different structures. The video also covers the digestion and storage of carbohydrates, lactose intolerance, and the difference between plant polysaccharides like cellulose, which humans cannot digest, and glycogen, which the body stores for energy.
Takeaways
- π‘ Carbohydrates are one of the four major macromolecules, along with proteins, fats, and nucleic acids.
- 𧬠Carbohydrates are composed of carbon, hydrogen, and oxygen atoms (carbo = carbon, hydrate = water).
- π Carbohydrates mainly function as a source of energy in the body and are found in cells and cell membranes.
- π¬ The three main types of monosaccharides are glucose, fructose, and galactose, all of which have the same chemical formula (C6H12O6) but differ in structure.
- π Glucose is the primary monosaccharide used for energy production in the body, while fructose and galactose are converted to glucose in the liver.
- π Disaccharides are formed by joining two monosaccharides through a dehydration reaction (removal of water). Examples include sucrose (glucose + fructose) and lactose (glucose + galactose).
- π§ͺ Lactose intolerance occurs when the body lacks the enzyme lactase, preventing the breakdown of lactose into glucose and galactose, which can lead to diarrhea due to osmotic effects.
- πΎ Polysaccharides, or complex carbohydrates, can be ingested from plants (starch, cellulose) or animals (glycogen).
- π₯¬ Humans cannot digest cellulose from plants (e.g., in leafy greens) due to the lack of necessary enzymes, while animals like cows can.
- 𧱠Glucose can be stored in the body as glycogen, a highly branched polysaccharide, for later energy use.
Q & A
What are the four major types of macromolecules mentioned in the script?
-The four major types of macromolecules are carbohydrates, proteins, fats, and nucleic acids.
What elements make up carbohydrates?
-Carbohydrates are made up of carbon, hydrogen, and oxygen.
What are the three main types of monosaccharides?
-The three main types of monosaccharides are glucose, fructose, and galactose.
How do glucose, fructose, and galactose differ chemically?
-They have the same chemical formula (C6H12O6) but differ in the arrangement of their atoms, making them isomers.
What happens to galactose and fructose in the liver?
-In the liver, galactose and fructose are converted into glucose for energy use or storage as glycogen.
What is a dehydration reaction, and how does it relate to carbohydrates?
-A dehydration reaction removes a water molecule to link sugar molecules together, forming disaccharides like sucrose and lactose.
Why do people with lactose intolerance experience digestive issues?
-People with lactose intolerance lack the enzyme lactase, which breaks down lactose. Without this enzyme, lactose remains undigested, leading to water retention in the intestines and resulting in diarrhea.
What is the difference between cellulose, starch, and glycogen?
-Cellulose is a long linear chain of glucose found in plants, starch is branched glucose from plants, and glycogen is highly branched glucose used by animals for energy storage.
Why can cows digest cellulose but humans cannot?
-Cows have the necessary enzymes to break down cellulose into glucose, while humans do not, making cellulose indigestible for us.
What role do polysaccharides play in the human diet?
-Polysaccharides like starch and glycogen can be broken down for energy in humans, while cellulose acts as fiber, aiding in digestion by bulking up stool.
Outlines
π¬ Carbohydrates: Composition and Structure
This paragraph introduces carbohydrates as one of the four major macromolecules, alongside proteins, fats, and nucleic acids. It explains that carbohydrates are composed of carbon, hydrogen, and oxygen. The basic structure of carbohydrates is hydrocarbons, and many carbohydrates form ring-shaped molecules. Carbohydrates can exist as monosaccharides (single sugar units), disaccharides (two sugar units), or polysaccharides (many sugar units). Their primary role in the body is energy production, although they are also found in cell membranes and genetic material.
π’ Types of Monosaccharides and Isomers
This section focuses on monosaccharides, highlighting three primary types: glucose, fructose, and galactose. Despite having the same chemical formula (C6H12O6), their structural arrangements differ, making them isomers. Glucose is the main monosaccharide used for energy. The liver converts fructose and galactose into glucose after absorption. Additionally, it explains the process of converting glucose into glycogen for storage. The paragraph discusses the role of monosaccharides in energy production and their structural properties.
βοΈ Disaccharides Formation and Lactose Intolerance
This paragraph explores the formation of disaccharides, like sucrose and lactose, through dehydration reactions where water is removed to link monosaccharides. It describes how sucrose (glucose + fructose) and lactose (glucose + galactose) are formed. The focus shifts to lactose intolerance, where some individuals lack the enzyme lactase, which is needed to break down lactose. Without lactase, lactose remains undigested in the intestines, leading to an osmotic effect where water is drawn into the intestines, resulting in diarrhea.
πΏ Polysaccharides and Fiber
This paragraph explains the differences between polysaccharides derived from plants and animals. It describes starch and cellulose from plants and glycogen from animals. Humans lack the enzymes needed to digest cellulose, which becomes dietary fiber that helps bulk up stool and move material through the intestines. In contrast, humans can digest starch and glycogen. The structural differences between these polysaccharides are explained, with cellulose being linear, starch slightly branched, and glycogen highly branched. The paragraph concludes by highlighting how carbohydrates are stored and used by the body.
Mindmap
Keywords
π‘Carbohydrates
π‘Monosaccharides
π‘Disaccharides
π‘Polysaccharides
π‘Dehydration reaction
π‘Glucose
π‘Lactose intolerance
π‘Glycogen
π‘Cellulose
π‘Isomers
Highlights
Carbohydrates are one of the four major macromolecules, alongside proteins, fats, and nucleic acids.
Carbohydrates are composed of carbon, hydrogen, and oxygen, similar to other macromolecules.
Monosaccharides are single sugar molecules, such as glucose, fructose, and galactose, all sharing the same chemical formula C6H12O6.
Glucose is the primary monosaccharide used for energy production in the human body.
Galactose and fructose are converted into glucose in the liver, where it can either be used for energy or stored as glycogen.
Disaccharides, such as sucrose and lactose, are formed through dehydration reactions, which involve the removal of water molecules.
Lactose intolerance occurs when the enzyme lactase is not present to break down lactose into glucose and galactose, leading to digestive issues like diarrhea.
Polysaccharides are long chains of sugar molecules and include starch (from plants), cellulose (from plants), and glycogen (from animals).
Humans can digest starch and glycogen but cannot digest cellulose, which forms dietary fiber.
Cellulose is a polysaccharide found in plant material like leafy greens and grass, but humans lack the enzymes to break it down.
Cows can digest cellulose because they possess the necessary enzymes to break down these polysaccharides.
Glycogen is the stored form of glucose in animals and is highly branched compared to plant starch.
The dehydration process links monosaccharides to form disaccharides, whereas rehydration (adding water) breaks these bonds.
The osmotic effect of undigested lactose pulling water into the intestines explains why lactose intolerance often results in diarrhea.
Fiber from indigestible polysaccharides bulks up stool and aids in digestion by pushing food through the intestines.
Transcripts
[Music]
I've run dr. Mike here let's talk about
carbohydrates as one of the four major
types of macromolecules remember you got
carbs proteins fats and nucleic acids
also known as nucleotides now
carbohydrates if we think about what
they composed of you'll find that
carbohydrates are composed of carbo
being carbon atoms hydrate talking about
water we know water is made up of
hydrogen and oxygen so carbohydrates are
made up of carbon hydrogen and oxygen
that's basically it you'll find that all
these macromolecules whether it be
proteins fats carbs or nucleic acids are
simply made up of hydrocarbons being a
bunch of carbons connected to a bunch of
hydrogen's now when we look at
carbohydrates pretty much all of them
are in this ring shaped fashion and you
can either have them alone which we call
monosaccharides meaning one sugar you
can have them connected together which
we call disaccharides so that's two
sugar molecules click together or you
can have a whole bunch of them click
together which we call polysaccharides
now the human body by mass is made up of
1% carbohydrates and predominately we
use carbohydrates for energy you'll find
carbohydrates on cells in cell membranes
you'll find them associated with genetic
material but predominantly the
functional role for carbohydrates is
going to be energy production now if we
have a look there's three main types of
monosaccharides the simple return the
simple sugars and this includes glucose
fructose and galactose which you've
probably heard of before now if you have
a look they are all made up of carbons
hydrogen's and oxygens and you'll
actually find that they have the exact
same chemical formula c6 h-12 o-6 so
there's six carbons 12 hydrogen's and
six oxygens the only difference between
those three is that they're arranged
differently so glucose which is our
primary monosaccharide this is the main
one we used to produce energy you can
see this is the arrangement of all the
carbons or the hydrogen's or the oxygens
okay you can see the carbon ring
with all the hydrogen and oxygen coming
off then when we look at fructose still
c6h12o6 it looks very similar but there
are a couple of differences same goes
for galactose very similar couple of
differences they're termed isomers of
glucose in actual fact when you ingest
foodstuffs what will happen is once it's
absorbed from the intestines into your
bloodstream it goes to your liver your
liver will convert galactose and
fructose to glucose either to use the
glucose for energy or to store the
glucose as a polysaccharide which we
term glycogen but I'll get to that in
one second now what can happen is you
can ingest these carbohydrates as
disaccharides and when you have a look
at these carbohydrates for example if
you were to connect a glucose and
galactose together you'd have to do it
through a process called dehydration
you've heard that term before
dehydration it means you don't have
enough water in your body right so a
dehydration reaction simply means you
release or you remove a water molecule
from the reaction it's very easy if we
first start off by connecting a glucose
with a fructose for example that's terms
sucrose so that's sucrose is simply a
glucose connected to a fructose the way
you do it through a dehydration reaction
is water needs to be removed water is
h2o two hydrogen one oxygen there's a
hydrogen there's a hydrogen there's an
oxygen so you remove them away and then
those two carbons can click together
that's how you form a sucrose in a
dehydration reaction when you want to
separate them it's a rehydration
reaction you're going to put that water
molecule back in now if we were to
connect glucose and galactose together
we form something that's called lactose
and some people are lactose intolerant
which means when they ingest milk
products where you predominately find
glucose and galactose stuck together
you need an enzyme in your body that
snips
off that to bonds so remember you got
that water molecule that's you've taken
away that water molecule the carbons are
held together you need to rehydrate to
break them apart and you need an enzyme
to do this rehydration process when
you're rehydrating that of lactose it's
an enzyme called lactase ASAE
for some of us we no longer produce
lactase and so we don't have the
scissors that allows for us to cut that
bond and so what happens is the glucose
and the galactose remain stuck together
and continue to move through our
intestines we need to break this down
into glucose and galactose in order for
it to get absorbed it from our
intestines into the bloodstream so we
can use it if it doesn't snap apart to
this hydration process they stay
together and it continues to move
through the digestive tract now this is
a larger molecule and when you've got
larger molecules moving in bulk
through your intestines it actually
pulls water towards it this is called an
osmotic effect and if it pulls water
towards it now your intestines are
filled with water and that goes out in
the fecal material which we call
diarrhea so this is why lactose
intolerance can result in diarrhea okay
the other thing is what if we were to
click together fructose and galactose
well in actual fact this doesn't happen
so you don't actually get a disaccharide
or fructose and galactose now like I
said fructose and galactose will
ultimately turn in at the liver to
glucose and so now we've got a whole
bunch of glucose molecules in our liver
we can either use it to form ATP energy
or we can store it and click all the
glucose molecules together to form what
we call polysaccharides which means many
sugars now there's different types you
can actually ingest polysaccharides from
plants and they are called starches or
cellulose okay or you can ingest it from
animals which is called glycogen and we
store our glucose as glycogen okay now
the thing is when you ingest a
polysaccharide a cellulose from a plant
material we don't have the enzymes that
break those bonds remember that
rehydrate the process so cellulose which
you find in leafy greens you also find
in lettuce you find even in grass for
example if we were to eat grass which we
don't do there's heaps of carbohydrates
there but we can't break them up into
these monosaccharides because we don't
have the enzymes now cows for example do
have the enzymes so they can get all the
energy they need from just eating grass
but we can't okay so what happens is we
eat lettuce for example we don't break
it down but it forms fiber so fire by
these indigestible polysaccharides that
we can't break down bulks up the stool
helps push everything through but we do
have the enzyme that breaks down starch
and glycogen okay and we can see is the
way they're stacked together a different
for cellulose it's one long linear bit
of glucose connected together starch is
a whole bunch of glucose molecules
connected together in a branch like
fashion and glycogen is extremely branch
and this is the way that we store
glucose so when we look at macro
molecules this is how carbohydrates are
stored and made
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