Carbohydrates AP Biology Topics 1.4 & 1.5
Summary
TLDRThis educational video script delves into the chemistry of carbohydrates, focusing on their structure and function. It covers the photosynthesis process where plants convert carbon dioxide and water into glucose. The script explains different types of monosaccharides like glucose, fructose, and galactose, and their role in forming disaccharides and polysaccharides through dehydration synthesis. It further discusses the functions of polysaccharides in plants, such as starch for energy storage and cellulose for structural support, and in animals, like glycogen for short-term energy storage. The script also touches on the conversion of excess glucose into fatty acids for long-term energy storage and the role of hydrolysis in breaking down carbohydrates during digestion.
Takeaways
- 🌿 **Photosynthesis**: Plants convert carbon dioxide and water into glucose, a carbohydrate, through photosynthesis.
- 🍬 **Monosaccharides**: Glucose, fructose, and galactose are examples of monosaccharides, which are single sugars composed of carbon, hydrogen, and oxygen.
- 🔗 **Disaccharides**: Two monosaccharides can join together through dehydration synthesis to form a disaccharide, like sucrose (glucose + fructose).
- 🔄 **Hydrolysis**: The process of breaking down disaccharides into monosaccharides by adding water is called hydrolysis.
- 🌱 **Starch and Cellulose**: Starch is a polysaccharide used for energy storage in plants, while cellulose provides structural support.
- 📦 **Polysaccharides**: Polysaccharides are long chains of glucose molecules, including starch, glycogen, and cellulose, each serving different functions.
- 🥩 **Glycogen**: In animals, glycogen is the storage form of glucose, similar to starch in plants, and is stored in the liver and muscles.
- 🍔 **Carbohydrate Metabolism**: Excess glucose is converted into fatty acids for long-term energy storage when glycogen stores are full.
- 🏋️♂️ **Exercise and Glycogen**: During exercise, stored glycogen is broken down into glucose to raise blood sugar levels and provide energy.
- 🔑 **Structural Differences**: The structure of polysaccharides, such as the straight chains in cellulose and branched chains in glycogen, determines their function.
Q & A
What are the primary elements used to build carbohydrates?
-Carbohydrates are primarily built using carbon (C), hydrogen (H), and oxygen (O), which plants obtain from carbon dioxide in the air and water from the soil.
How does the process of photosynthesis contribute to the formation of glucose?
-Photosynthesis is the process by which plants rearrange carbon dioxide and water into glucose, a simple sugar. This process involves the rearrangement of these molecules to form glucose, which has a hexagonal shape.
What is the chemical formula for glucose?
-The chemical formula for glucose is C6H12O6.
What is the scientific term for a single sugar, and what does it mean?
-The scientific term for a single sugar is 'monosaccharide', where 'saccharide' means sugar and 'mono' means one.
How do glucose and fructose differ in their molecular structure?
-Glucose is a six-carbon sugar, while fructose is a five-carbon sugar. Both are composed of carbon, hydrogen, and oxygen.
What is a disaccharide and how is it formed?
-A disaccharide is a carbohydrate formed by the joining of two monosaccharides through a dehydration synthesis reaction, which involves the removal of a water molecule to form a covalent bond between the two sugars.
What is the term for the bond formed between two monosaccharides in a disaccharide?
-The bond formed between two monosaccharides in a disaccharide is called a glycosidic linkage.
How does the process of hydrolysis relate to the digestion of disaccharides?
-Hydrolysis is the process of breaking down a disaccharide by adding a water molecule, which is facilitated by enzymes in saliva. This process splits the disaccharide into its constituent monosaccharides.
What are the two main functions of glucose in plants?
-In plants, glucose serves two main functions: it can be used as an immediate energy source, or it can be stored for later use, often in the form of starch or cellulose.
What is the difference between starch and cellulose in plants?
-Starch is an energy storage polysaccharide in plants, while cellulose provides structural support and forms the cell walls. The difference lies in the type of glycosidic linkages between glucose monomers, with starch having alpha linkages and cellulose having alternating alpha and beta linkages.
Why is cellulose indigestible to humans?
-Cellulose is indigestible to humans because we lack the enzymes necessary to hydrolyze the glycosidic linkages between the glucose monomers in cellulose, which are alpha and beta alternately linked.
How does the body manage excess glucose after a carbohydrate-rich meal?
-When blood sugar levels rise after consuming carbohydrates, the body responds by releasing insulin, which signals the liver and muscles to store excess glucose as glycogen through a process called dehydration synthesis.
What happens when the body's glycogen storage is full and blood sugar levels remain high?
-If glycogen storage is full and blood sugar levels are still high, the body converts excess glucose into fatty acids, which are then stored as fat for long-term energy storage.
Outlines
🌿 Carbohydrates: Structure and Function
This paragraph introduces the topic of carbohydrates, focusing on their structure and function, particularly in the context of AP Biology's unit on the chemistry of life. It explains how plants use carbon dioxide and water to create glucose through photosynthesis, highlighting the chemical formula for glucose (C6H12O6). The paragraph also discusses monosaccharides, specifically glucose, fructose, and galactose, and how they are formed from carbon dioxide and water. The concept of dehydration synthesis is introduced, explaining how two monosaccharides can combine to form a disaccharide through this process, creating a glycosidic linkage.
🌱 Plant Utilization of Glucose
The second paragraph delves into the dual functions of glucose in plants: energy storage and structural support. It describes how plants convert excess glucose into polysaccharides, which are chains of glucose molecules linked by glycosidic linkages. The paragraph introduces three main types of plant polysaccharides: starch (for energy storage), cellulose (for structural support), and briefly mentions chitin. It explains the process of photosynthesis, where plants convert glucose into starch for energy storage and cellulose for building cell walls. The difference between starch and cellulose is highlighted, with starch being digestible by humans due to our enzymes' ability to hydrolyze the glycosidic linkages, while cellulose is indigestible due to the different arrangement of glucose monomers.
🍽️ Carbohydrate Metabolism in Animals
Paragraph three explores the role of carbohydrates in animal metabolism, particularly in humans. It discusses how excess glucose from digestion is managed by the body to maintain homeostasis. The liver and muscles store excess glucose as glycogen, a polysaccharide similar to plant starch but used for short-term energy storage. When blood sugar levels are too high, insulin is released, signaling the liver and muscles to store glucose. If glycogen storage is maxed out, the body converts excess glucose into fatty acids for long-term energy storage. The paragraph also explains how exercise can deplete glycogen stores, leading to an increase in hunger as the body signals the need to replenish these stores.
🏋️♂️ Glycogen and Exercise
The final paragraph focuses on the role of glycogen during physical activity. It explains how the hormone glucagon triggers the hydrolysis of glycogen into monosaccharides to raise blood sugar levels during exercise, providing the necessary energy. The paragraph also touches on the different structural forms of carbohydrates, comparing the straight chains of cellulose, the single chains of amylose (a component of starch), and the branched structure of glycogen, which allows for efficient energy release by breaking off sections of glucose monomers.
Mindmap
Keywords
💡Carbohydrates
💡Photosynthesis
💡Monosaccharides
💡Disaccharides
💡Polysaccharides
💡Glycolysis
💡Dehydration Synthesis
💡Hydrolysis
💡Glycosidic Linkage
💡Cellulose
💡Glycogen
Highlights
Carbohydrates are essential organic molecules built from carbon dioxide and water during photosynthesis.
Glucose is a hexagon-shaped monosaccharide with the chemical formula C6H12O6.
Monosaccharides include glucose, fructose, and galactose, all composed of C, H, and O.
Disaccharides are formed by joining two monosaccharides through a dehydration synthesis process.
The bond formed between monosaccharides in a disaccharide is called a glycosidic linkage.
Cellular respiration begins with glycolysis, which is the splitting of sugar molecules.
Plants use glucose for energy storage or to build structural components like cell walls.
Starch is a polysaccharide used by plants for energy storage, found in high amounts in potatoes.
Cellulose is a polysaccharide that provides structural support and forms the cell walls in plants.
Humans cannot digest cellulose due to the lack of enzymes to break the glycosidic linkages.
Glycogen is the animal equivalent of starch, used for short-term energy storage.
The human body converts excess glucose into fatty acids for long-term energy storage.
Fatty acids are a compact form of potential energy that can be carried by the body.
Exercise depletes stored glycogen, leading to an increase in hunger as the body signals the need to replenish energy stores.
The structure of carbohydrates varies; cellulose forms rigid chains, starch forms straight chains, and glycogen has a branched structure.
Herbivores have bacteria that help them break down cellulose to obtain energy.
The body maintains homeostasis by regulating blood sugar levels with the help of insulin and glucagon.
Transcripts
okay so in this video we're gonna look
at the structure and function of
carbohydrates if you're in ap biology
this is unit 1 chemistry of life with a
major focus on one point four and one
point five okay so when we look at life
on Earth and what we have available to
build the organic molecules particularly
carbohydrates plants are going to take
that carbon dioxide and water from the
air and that's where they get the C H
and O in order to build carbohydrates so
here this carbon dioxide and this water
is going to be rearranged into a
molecule of glucose during the process
of photosynthesis so here this glucose
has CH and O and comes in like this
hexagon shape here and really um here's
what it is though a single sugar glucose
now when we look at these macromolecules
plants give their carbon hydrogen and
oxygen from the air and from the water
in the soil now ultimately for other
macromolecules they'll need nitrogen and
phosphorus but for carbohydrates we're
looking at C H and O okay so the
chemical formula for glucose is c6h12o6
all right so when we talk about sugars
or carbohydrates um the scientific name
is mono saccharide for one single sugar
so saccharide means sugar and mono means
one when we look at the different single
sugars or monosaccharides on earth we
have glucose which is going to be our
main monosaccharide and then we have
fructose which is fruit sugar and if you
look at the differences between these
two monosaccharides you can see that
glucose comes in a six carbon structure
and then fructose is five carbon sugar
they both however are made of C H and O
and then we have galactose and galactose
is part of the sugars in the breast milk
so that one is a little bit less common
on earth and so when we look at these
though they were all made
carbon dioxide and water during the
process of photosynthesis so if you were
to add however two sugars together like
this this is called a disaccharide dye
meaning two sugars and so if we think
about how do you join two
monosaccharides or two monomers together
in order to build a disaccharide well
we're going to do dehydration synthesis
and we're going to remove a water so now
we have a covalent bond right here in
the middle between the two
monosaccharides and the process of
removing a water to build is called
dehydration synthesis so this type of
bond though does have a name so we look
at the bond that was just formed by
dehydration synthesis removing a
hydrogen and a hydroxyl group from the
two monosaccharides this bond is called
a glycosidic linkage a lot of times when
you see the prefix with a GTL why it's
in reference to sugars or carbohydrates
so when we get to cellular respiration
that begins with glycolysis which is a
splitting of sugar okay so let's go
ahead and see when we take a
monosaccharides or a glucose and another
glucose an enzyme will actually
facilitate this reaction and remove the
water in dehydration synthesis and now
we have our disaccharide now enzymes are
pretty cool proteins that can be used
over and over and over again so here
we're taking monosaccharides to build
disaccharides
so here the monomer is a monosaccharide
or a glucose and then we don't quite
have a polymer but we do have a two
sugar molecule called disaccharide
now if we were to digest a disaccharide
like when you eat white table sugar for
example that's a sucrose molecule made
of glucose and fructose and what will
happen is our enzymes
saliva are going to add a water to split
in the process called hydrolysis so when
we split bonds by adding water that's
called hydro lysis or adding water to
split okay so let's talk a little bit
more about carbohydrates and their
functions so here we have chloroplasts
and chloroplasts do photosynthesis in
both the light and the dark reactions so
when a planet is going through
photosynthesis it's building technically
g3p but if you take a g3p and a g3p it
builds glucose together so plant is
building glucose and now what does it do
with it right well there's actually two
different functions that a plant can use
glucose for so here again as it does
photosynthesis it's going to one of the
functions could be that it saves the
extra excess glucose for a day when it's
not sunny or something so when a plant
though takes these excess glucose
molecules and builds them into a chain
there's many glucose molecules so we
call this poly saccharide so we look at
carbohydrates the monomer or the
building block is a single sugar a
single monosaccharides
this is called glucose then a polymer is
many glucose molecules so here we have
our polymer that we call a poly
saccharide now in between each of these
um glucose molecules these monomers is a
glycosidic linkage so in order to build
this molecule you see here this
polysaccharide we would actually have
produced 1 2 3 4 5 water molecules in
the building of this polysaccharide now
in our class there are there's actually
4 different types of polysaccharides
this one here we don't talk too much
about chitin but chitin is actually the
polysaccharide used to build
exoskeletons in lobsters and crabs and
beetles but this one we don't talk about
too much
now the other three are important and
all three of these starch glycogen and
cellulose they are all polysaccharides
all made from repeating glucose
molecules however they do serve
different functions so if you were to
compare and contrast them one thing they
have in common is they're all a chain of
glucose molecules okay so let's go ahead
and see what plants do with these
polysaccharides so in plants that are
two main types of polysaccharides we
have starch and we have cellulose so
starch is going to be the energy storage
for plants when you eat a potato you
were eating starch and that is a chain
of glucose molecules being saved by the
plant when you grow up and you hear that
plants make their own food this is it
they're making glucose and they're
storing it for times when they need
energy and then plants will use
cellulose another type of polysaccharide
however cellulose is used for structural
reasons this is what builds the cell
walls in plants so when we look at the
polysaccharides in plants they are both
a chain of glucose molecules however one
is for energy storage and one is for
structural support and then fiber for us
as well
so if I have the leaves of a plant doing
photosynthesis and it's gonna save the
glucose molecules for later the
photosynthesis happens in the leaves but
the sugars will travel from the leaves
and then be stored here in the plant now
plants though so this molecule is gonna
be starch an energy storage
polysaccharide however a plant also
grows and when you think about well how
does it build new cells and new cell
walls those cell walls are going to be
made from glucose as well however the
bonds from those glucose is joining
together are going to be slightly
different than the bonds you find in
starch and it's these the different ways
these
two monomers joined together that
results in the different properties okay
so let's go ahead and look at cellulose
so silos are those rigid AB cell walls
and plants to offer support and
protection now another cool thing about
cellulose is that we do not have the
enzymes to hydrolyze cellulose we cannot
break down this chain of glucose and
therefore cellulose is not free
available energy you will not get enough
energy to support life if you just eat
lettuce every day there's not enough
energy in it to support us you may be
thinking about herbivores though and
herbivores have bacteria in their
stomachs and intestines to help them
break these bonds and break it down and
get the energy from these molecules okay
so let's go ahead and see what makes
them different well we have two
different types of glucose we have the
alpha ring form and we have the beta
ring form and you can kind of see it
here slight variations and the two
glucose molecules now this is
significant for when they join by
dehydration synthesis to form a
polysaccharide so in starch it is made
of alpha alpha alpha alpha glucose
monomers joined together now in
cellulose it's made of alpha glucose
beta glucose alphabet glucose beta
glucose so the it like alternates a type
of glucose monomers so if i zoom into
those glycosidic linkages I see this
linkage and this one and they are
different we can to adjust and break
apart the monomers in starch however we
cannot break that glycosidic linkage
between an alpha glucose and a beta
glucose so therefore cellulose is
indigestible by us so starch while we
have the enzymes that can do hydrolysis
we can add waters and break that
polysaccharide down into its individual
monomers of glucose however cellulose is
hard
to digest and we do not have the enzymes
to break those bonds therefore it
remains intact as we eat it okay now for
animals we also have a polysaccharide
but we're not gonna use starch because
I'm not a plant instead we eat those
plants and we eat that starch and we
don't use cellulose because we don't
build cell walls but let's take our
blood sugar for example we have sugar
flowing in our blood and we try real
hard to maintain homeostasis and keep
things balanced however when we eat a
meal that's full of sugar carbohydrates
as our enzymes hydrolyze and break down
those large carbohydrates into
individual sugars our blood sugar Rises
and now we're not in homeostasis anymore
so our body kind of like had too much
sugar we have to do something about it
and so what we do is we have our liver
and our muscles and our liver at our
muscles store this extra sugar for us we
can store about 24 hours worth of sugar
in our livers so what happens is when
our blood sugar is too high our pancreas
will release insulin and that will
communicate to our liver and our muscles
that it's time to take sugar out of our
blood and store it so that's a really
cool thing so right now as that second
sugar came down dehydration synthesis is
happening right here to form a
glycosidic linkage
here's another glycosidic linkage etc so
we end up with the chain of glucose
monomers joined together in our liver
and our are we back in homeostasis not
quite we still have a couple of extra
glucose but for now the name of this
polysaccharide in animals is glycogen so
its purpose however is very similar to
starch in a plant while starch in a
plant is storing glucose for energy this
glycogen stores our glucose for energy
for like a short-term amount for us as I
mentioned earlier we store about 24
hours
the glucose in our liver and we store it
as the polysaccharide called glycogen so
let's say though that your your liver is
full it's at capacity you can't fit any
more glucose molecules in it like your
glycogen czar maxed out and you still
have too high of blood sugar well then
your body has the ability now let's
think about this your carbohydrates are
made of C H and O your lipids are made
of C H and O so what we can do with that
excess sugar that excess glucose is we
actually convert it into fatty acids you
can see all the hydrogen's and carbons
here we call this a fatty acid which is
a non-polar molecule it's a part of the
lipid category of macromolecules and so
what we'll do is that's how we're gonna
take that extra sugar out of our blood
and now the cool thing about fatty acids
is this we are saving this potential
energy and we can carry it around with
us so this fat is actually like a
survival mechanism for humans we eat
when we have a lot of food available to
us and then any energy we don't need in
the next 24 hours we can save for later
for times when we don't have access to
food so these hydrocarbons right here
are actually a lot of potential energy
and a nice compact shape being carried
around with us okay so when we look back
at homeostasis um let's say you go and
exercise well as you exercise you're
gonna use that blood sugar to power your
workout and this is where that stored
glycogen so the hormone is glucagon but
this polysaccharide was glycogen and
that's where we will actually do
hydrolysis so right here we're gonna do
how this hormone right here is going to
activate an enzyme that will do
hydrolysis to break that polysaccharide
into monosaccharides and Rhea
or right yeah raise our blood sugar back
so we can continue our workout this
empty liver here is also why you're
really hungry after you exercise
that's your brains way of telling you Oh
fill your liver back up okay so um now
when we look at the different shapes of
carbohydrates
you can see how cellulose which forms
like a rigid cell wall so it makes sense
that they're in very straight chains and
then starch um it amylose is our main
one is like a a single line a chain of
glucose monomers and then look at this
glycogen though we can just its branched
and we can just break off like sections
I have these carbohydrates to add to our
blood sugar to keep us on homeostasis
alright good job
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