Organic chemistry screencast segment 3 - Carbohydrates.mp4

Summary

In this engaging screencast, Mr. Workman delves into the world of organic chemistry, focusing on carbohydrates. He explains their chemical composition, highlighting the 1:2:1 ratio of carbon, hydrogen, and oxygen atoms. Monosaccharides, disaccharides, and polysaccharides are discussed, with examples like glucose, fructose, and sucrose. The video also touches on the hydrophilic nature of sugars due to their polar bonds and their role in energy transfer and storage. Mr. Workman emphasizes the difference between structural and energy storage polysaccharides, like cellulose and starch, and their importance in nutrition and biology.

Takeaways

• 📚 Carbohydrates are composed of carbon, hydrogen, and oxygen, with a ratio of 1:2:1 respectively.
• 🔍 The term 'carbohydrate' should not be confused with 'hydrocarbons'; the former contains oxygen, while the latter does not.
• 🍬 Monosaccharides, or simple sugars, are the basic building blocks of carbohydrates.
• 🔗 Disaccharides are formed by the linkage of two monosaccharides through a dehydration synthesis reaction.
• 🌐 Polysaccharides are complex carbohydrates formed by the repeated linkage of many monosaccharides.
• 🧪 The general empirical formula for monosaccharides is CH2O, indicating twice as many hydrogens as carbons.
• 🔑 Glucose and fructose are examples of monosaccharides that are isomers, having the same molecular formula but different structural arrangements.
• 🍰 Sucrose, commonly known as table sugar, is a disaccharide composed of glucose and fructose linked by a glycosidic linkage.
• 🥔 Starch is the energy storage polysaccharide in plants, while glycogen serves the same purpose in animals.
• 🌾 Cellulose is the structural polysaccharide in plants, and chitin serves a similar role in arthropods and some fungi.

Q & A

What is the defining ratio of atoms in a carbohydrate?

Carbohydrates have a defining ratio of carbon, hydrogen, and oxygen atoms in a 1:2:1 ratio.

How do carbohydrates differ from hydrocarbons?

Carbohydrates contain carbon, hydrogen, and oxygen, whereas hydrocarbons contain only carbon and hydrogen.

What is the basic building block of carbohydrates known as?

The basic building block of carbohydrates is known as monosaccharides.

How are disaccharides formed?

Disaccharides are formed by linking two monosaccharides together through a dehydration synthesis or condensation synthesis reaction.

What is the general empirical formula for monosaccharides?

The general empirical formula for monosaccharides is CH2O, indicating twice as many hydrogens as carbons.

What is the difference between aldose and keto sugars?

Aldose sugars have their carbonyl group (C=O) at the end of the carbon chain, forming an aldehyde, while keto sugars have their carbonyl group somewhere in the middle of the chain.

Why are monosaccharides hydrophilic?

Monosaccharides are hydrophilic due to their polar covalent bonds, particularly the O-H and C=O bonds, which allow them to interact with water.

What is the role of glycosidic linkage in carbohydrates?

Glycosidic linkage is the strong covalent bond that links monosaccharides together in disaccharides and polysaccharides.

How does the human body utilize complex carbohydrates?

The human body utilizes complex carbohydrates for energy storage and to provide sustained energy over a longer period, which can help prevent energy crashes.

What are the structural polysaccharides in plants and animals?

The structural polysaccharides in plants are cellulose molecules, while in animals, it is chitin found in exoskeletons.

Why can't humans digest cellulose?

Humans can't digest cellulose because they lack the enzyme necessary to break down the strong glycosidic linkages and cross-bridging found in cellulose.

Outlines

00:00

🔬 Introduction to Carbohydrates

This segment introduces the topic of carbohydrates in organic chemistry. Mr. Workman emphasizes the importance of taking detailed notes, including definitions, explanations, and diagrams. Carbohydrates are distinguished from hydrocarbons by their composition of carbon, hydrogen, and oxygen in a 1:2:1 ratio. The building blocks of carbohydrates are monosaccharides, which can be linked together to form disaccharides and polysaccharides through dehydration synthesis. Monosaccharides are commonly referred to as sugars, while polysaccharides are known as complex carbohydrates. The general empirical formula for sugars is Cn(H2O)n, indicating twice as many hydrogens as carbons. The segment also highlights the difference between aldose sugars like glucose and ketose sugars like fructose, despite their similar molecular composition.

05:01

🌿 Properties and Formation of Sugars

This paragraph delves into the characteristics of monosaccharides, highlighting their polar covalent bonds which make them hydrophilic. The discussion includes the various forms of monosaccharides, such as straight chains or ring structures. It explains that monosaccharides like glucose, fructose, galactose, and mannose are all isomers, having the same chemical formula but different structural arrangements. The paragraph also covers the formation of disaccharides like sucrose through glycosidic linkages, which are strong covalent bonds. The difference in the molecular formula of sucrose compared to the sum of its constituent monosaccharides is explained, accounting for the removal of water molecules during the linkage process.

10:05

🍚 Functions of Polysaccharides

The third paragraph focuses on polysaccharides, which are large and complex carbohydrates. It discusses the primary functions of monosaccharides and disaccharides as energy transfer and storage, contrasting the quick energy boost from simple sugars with the potential for a subsequent energy crash. The concept of carbo-loading is introduced, explaining how consuming complex carbohydrates like starch can provide sustained energy. The paragraph also distinguishes between energy storage polysaccharides like starch in plants and glycogen in animals, and structural polysaccharides like cellulose in plants and chitin in animals and arthropods. The importance of these molecules in building cells and tissues is emphasized.

15:06

🥗 Digestibility and Nutritional Aspects of Polysaccharides

The final paragraph discusses the digestibility of polysaccharides, noting that humans lack the enzymes to break down cellulose, which is why it provides dietary fiber. It contrasts this with the ability of cows and termites to digest cellulose due to the presence of necessary enzymes. The structural differences between cellulose and chitin are highlighted, with chitin containing nitrogen cross-linkages that make it tougher. The paragraph concludes by mentioning that while some forms of chitin, like that in soft-shell crabs, can be digested by humans, tougher exoskeletons like those of lobsters and shrimp are inedible. The segment ends with an invitation for questions and a预告 of the next screencast segment.

Keywords

💡Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen, typically in a 1:2:1 ratio. They are a crucial source of energy for living organisms. In the script, carbohydrates are distinguished from hydrocarbons, which lack oxygen. The video discusses how carbohydrates can be simple (like monosaccharides and disaccharides) or complex (like polysaccharides), and their roles in nutrition and energy storage.

💡Monosaccharides

Monosaccharides are the simplest form of carbohydrates and are also known as simple sugars. They cannot be hydrolyzed into simpler sugars. Examples include glucose, fructose, and galactose, all of which have the same chemical formula (C6H12O6) but differ in structure. The script explains that monosaccharides are the building blocks for more complex carbohydrates.

💡Disaccharides

Disaccharides are carbohydrates formed by the dehydration synthesis of two monosaccharide molecules. They are considered simple sugars. The script mentions sucrose (table sugar), which is composed of glucose and fructose, and lactose, found in milk. These are formed through a condensation reaction where water is removed, creating a glycosidic linkage.

💡Polysaccharides

Polysaccharides are complex carbohydrates consisting of long chains of monosaccharide units. They serve as energy storage or structural components. The script discusses starch (found in plants) and glycogen (found in animals) as energy storage polysaccharides, and cellulose (in plant cell walls) and chitin (in arthropod exoskeletons) as structural polysaccharides.

💡Aldose and Ketose

Aldose and ketose are terms used to describe the functional groups present in monosaccharides. Aldose sugars have an aldehyde group at the end of their carbon chain, like glucose, while ketose sugars have a ketone group elsewhere in the chain, like fructose. The script uses these terms to explain the structural differences between glucose and fructose.

💡Hydrophilic

Hydrophilic means 'water-loving' and describes molecules that interact well with water due to their polar nature. In the script, it is mentioned that monosaccharides are hydrophilic because of their polar covalent bonds, which allows them to dissolve in water and interact with other polar molecules.

💡Isomers

Isomers are molecules with the same molecular formula but different structural arrangements. The script uses glucose and fructose as examples of isomers, both having the formula C6H12O6 but differing in the arrangement of atoms, which results in different properties and functions.

💡Glycosidic Linkage

A glycosidic linkage is the covalent bond formed between two monosaccharides in a disaccharide or between monosaccharide units in polysaccharides. The script explains that this bond is strong and requires specific enzymes to break it down, which is why humans cannot digest cellulose but can digest sucrose.

💡Starch

Starch is a polysaccharide and the primary form of energy storage in plants. It is composed of glucose units and can be either amylose (linear) or amylopectin (branched). The script mentions that starch is found in foods like potatoes, pasta, and bread, and is a source of energy for humans.

💡Glycogen

Glycogen is the animal equivalent of starch and serves as the primary energy storage molecule in animals. It is a highly branched polymer of glucose. The script notes that glycogen is stored in the liver and muscles and can be quickly mobilized for energy when needed.

💡Cellulose

Cellulose is a structural polysaccharide found in the cell walls of plants. It is a long chain of glucose units linked by β-1,4-glycosidic bonds, which gives it a high degree of strength and rigidity. The script explains that humans lack the enzyme to break down cellulose, which is why it provides dietary fiber.

Highlights

Introduction to carbohydrates and their components: carbon, hydrogen, and oxygen.

Difference between carbohydrates and hydrocarbons: carbohydrates contain oxygen.

Carbohydrate ratio: 1:2:1 for carbon, hydrogen, and oxygen.

Monosaccharides are the building blocks of carbohydrates.

Dehydration synthesis links monosaccharides to form disaccharides.

Polysaccharides are complex carbohydrates formed by linking multiple monosaccharides.

Glucose is an aldose sugar with a C=O group at the end of the chain.

Fructose is a ketose sugar with the C=O group in the middle of the carbon chain.

Sugars are hydrophilic due to polar bonds and their interaction with water.

Isomers: molecules with the same chemical formula but different arrangements.

Glucose and fructose are isomers and combine to form sucrose.

Sucrose formation involves a glycosidic linkage between glucose and fructose.

Polysaccharides are used for energy storage (starch in plants, glycogen in animals).

Cellulose and chitin are structural polysaccharides in plants and animals, respectively.

Humans cannot digest cellulose, but it acts as dietary fiber in nutrition.

Transcripts

hello biology 400 this is mr. workman

and this will be your organic chemistry

screencast segment three on

carbohydrates as you view this

screencast please make sure that you

have some paper with you so that you can

take good two-column notes and write

down of course any definitions any

explanations even diagram oh and draw

some of the figures that you see that

you think are going to be important to

your understanding of carbohydrates

let's get to it so let's talk about how

you can recognize what a carbohydrate is

first of all if you look at this word

carb oh that is like carbon and if you

look at hydrate here and that looks like

hydrogen don't confuse these

carbohydrates with hydrocarbons

carbohydrates contain carbon oxygen and

hydrogen hydrocarbons on the other hand

contain just carbon and hydrogen they do

not contain any oxygen so pardon me if

you see a molecule that contains the

atoms carbon hydrogen and oxygen in a

one to two to one ratio you're most

likely looking at a carbohydrate so this

1 to 2 to 1 ratio this one to one refers

to carbon hydrogen and oxygen in other

words there are twice as many hydrogen's

as there are carbons there are also

twice as many hydrogen's as there are

oxygens and the number of carbons and

the number of oxygens will be just about

equal the building blocks of

carbohydrates the monomers the single

units that is are referred to as

monosaccharides and if you like two

monosaccharides together by way of

dehydration synthesis or the formation

of water condensation synthesis you get

what we call a dasa disaccharide and if

that process happens over and over again

we get what we call polysaccharides

monosaccharides are simply referred to

as sugars in everyday language sometimes

called simple sugars disaccharides can

be fairly classified as simple sugars as

well whereas polysaccharides are

referred to in the nutritional world as

complex carbohydrates or complex sugars

when you look at the formula of any

sugar the general empirical formula is

going to be C h2o and how often that

repeats depends on how big of a

carbohydrate we're talking about this is

just another way to show that there's

going to be twice as many hydrogen's as

there are carbons so let let's look at

this hydrocarbon hexane this word this

prefix on this word hex means six can

you see here that there are six carbons

lined up in a chain and they're

surrounded by enough hydrogen it's fully

saturated with hydrogen so that each

carbon is making four bonds as required

by its tetra valency in contrast if you

look over here these chains of six

carbons are a little bit more

interesting do you see why there are

some oxygens there's a C double bond o

here this one is another chain of six

carbons here's a C double bond o and I

want to let you know that this diagram

is actually inaccurate this hydrogen

should not be here that hydrogen would

indicate that this carbon is making five

bonds so this hydrogen is actually an

error in this diagram take a look at the

difference between these two molecules

glucose and fructose you can see here

that this is called an aldose sugar and

this is called a keto sugar but if you

count up the total number of carbons and

hydrogen's and oxygens they have the

same number of carbons they have the

same number of hydrogen's in the same

number of oxygens the way that they

differ is in how those carbons and

hydrogen's and ox

Asians are put together the way that

they're arranged and you can see here

that the C double bond o and glucose is

at the end of the chain of carbons so

it's on the last carbon and as a result

that's an aldehyde so we call glucose

and aldose sugar you might start to note

that many sugars are named with the

ending OS e okay so glucose OSE fructose

OSE fructose is a ketose sugar because

it's carbonyl it's C double bond o is

not at the end of the chain of carbons

it's somewhere in the middle of the

chain of carbons monosaccharides some

characteristics of sugar you know the

fact that they have polar bonds in them

polar covalent bonds if you remember

your electronegativity bonding rules

oxygen bonded to hydrogen is a moderate

difference in electronegativity see

carbon bonded to oxygen especially a

double bond that's gonna be a polar bond

because there's a moderate difference in

electronegativity there there's o H

bonds and they're Co bonds all over this

molecule which means because there are

lots of polar bonds in this molecule

it'll interact with water which is also

a polar molecule so because sugars will

interact with water they are literally

water loving they're called hydrophilic

because of their polar bonds that they

contain monosaccharides can be found in

six carbon chains straight chains or

sometimes they can fold back on

themselves as you see here in the form

of rings sorry about that

so look at this do you notice that this

is a roughly a hexagon shape I want you

to make note of that because we're gonna

see some diagrams you've already seen

some diagrams and you're gonna see some

more diagrams where not all these

carbons are necessarily noted glucose

and fructose as mentioned on the earlier

slide as well as galactose and mannose

are all I know saccharides and they all

have six carbons they all have 12

hydrogen's and they all have six oxygens

so let's think about why would there be

four different names for molecules that

all have this same formula with six

carbons 12 hydrogen's and six oxygens

well the answer is that these molecules

are all isomers of one another an isomer

is a molecule or isomers our molecules

that have the same chemical formula all

right so that means that have the same

types of atoms the same number of atoms

but that those atoms are arranged in a

different pattern so same pieces just

built differently so picture me giving

you 24 Legos and me giving somebody else

24 Legos and all those same Legos were

used but built up and connected

differently you know that's a fair way

to think about what an isomer is here's

glucose and here's fructose and I do

want to let you know that fructose is

named for fruit sugars we find fructose

a lot in fruit sugars and fructose can

be commonly linked to glucose to form

what we call common table sugar which is

sucrose right the stuff that you

actually sprinkle out onto your Wheaties

to make them taste better the stuff that

you know donuts and really high sugar

content

he has a ton of is sucrose sucrose of

course is what we would refer to as a

disaccharide

as stated before monosaccharides and

disaccharides are fairly classified as

simple sugars do you recall what the

formula is for a monosaccharide that's

right

it's c6 h-12 o-6 so when you link two

monosaccharides together you'd think

that there would be two times six

carbons which is 12 2 times 12

hydrogen's which is 24 and 2 times 6

oxygens which is 12 so let's think about

why this formulas for sucrose is c12 h22

o11 well you got to take out two

hydrogen's and you got to take out one

oxygen because when these are linked

together water is made so if you add up

the c6 h-12 o-6

and the c6 h-12 o-6 and you take away

two H's and 100 you get c12 h22 o11 this

bond right here between the first carbon

of this glucose and the second carbon of

this fructose is referred to as a

glycosidic linkage alright there's that

term glycosidic linkage it's a really

strong covalent bond that keeps this

monosaccharides linked to this

monosaccharide

taking that same concept further than we

have what we call polysaccharides these

of course are gonna be the large more

complex carbohydrates so if you think of

complex carbohydrates or complex sugars

as I stated nutrition in the nutritional

language those are they're gonna be the

big big big sugar molecules lots and

lots and lots and lots of

monosaccharides maybe thousands of

monosaccharides the primary purpose of

course of the monosaccharides and the

disaccharides are going to be energy

transfer and energy storage you eat

sugar you get lots of energy very

rapidly but you might crash I don't know

if you've ever heard of the sugar crash

so if you eat or drink a high sugar

content a simple sugar content food or

drink you might feel energetic for a few

minutes or maybe an hour so and then all

of a sudden a couple hours later you

feel really tired and maybe even lousy

again so sometimes athletes will

carbo-load maybe you've heard of carbo

loading you eat pasta or bread and what

you're doing when you're carbo loading

you're eating lots of complex

carbohydrates namely you're eating lots

of starch all right so you're getting

lots of sugar complex polysaccharides

sugars from plant materials and your

body has to work a little bit and it

takes a little bit of time to actually

break down this sugar because it's such

a big molecule so in a way if you carbo

load with large complex sugars it

provides you with energy for a

significant period of time and you won't

necessarily experience the crash that

you would if you are eating or drinking

a lot of simple sugars the other primary

function or purpose of large

polysaccharide molecules of course is

structural in nature so these are

materials that are used to build cells

or build tissues that cells will build

up themselves

the energy storage polysaccharides let's

make sure we write this down now the

energy storage polysaccharides the one

for plants is called starch this is a

photo graph using a microscope right so

we call it a photo micrograph is showing

you a mill applies which are starch

grains found within the cell of a plant

this is a photo micrograph or a

microscope a microscope photograph a

micrograph of animal cells and there's

been a stain used here to highlight the

glycogen material in red so starch is

the energy storage polysaccharide in

plants glycogen is the energy storage

polysaccharide in animals lactose is

another disaccharide that you might have

heard of and if you think of the word

lactate that's the process of making

milk and it's sort of an odd thing to

think about that humans are the only

mammals that drink other mammals milks

and you know we drink a lot of cow's

milk because the dairy industry tells us

it's good for us but actually for some

of us it's really not because we don't

have the enzyme that breaks down this

disaccharide not all of us do anyway and

not all of us have the enzyme that

breaks down this disaccharide that's

found in dairy material like milk or

cheese starch of course is a

polysaccharide if you eat potatoes

french fries chips pasta bread those

foods are loaded with starch if you're a

meat-eater if you're a carnivore

sometimes you might be at steak or

hamburger or chicken or pork chops or

something like that depending on what

you like to eat understand that when you

eat meat of course you're getting a

source of protein there but within those

muscle cells glycogen will also likely

be stored

these are polysaccharides

the structural polysaccharides for

plants are cellulose molecules cellulose

is a huge vast many many many many many

monosaccharides linked together in long

chains as well as cross bridges the

structural polysaccharide in animals we

call chitin and chitin is found in the

cuticle or the exoskeleton of insects

arthropods that is which are insects are

either pods or pods and so to our

crustaceans if you look at this diagram

here this is showing you a cellulose

molecule and notice that each individual

little hexagon here represents a

monosaccharide they're linked together

with glycosidic linkages but there's

also cross bridging here and the greater

the amount of cross bridging the tougher

this cellulose material is and this

cross bridging and these glycosidic

linkages are really really really

difficult to break down unless you have

the right enzyme in your digestive tract

to break it up humans don't have that

enzyme and so when we eat salad or other

cellulose material we're getting what

the nutritionists call fiber fiber helps

keep us regular and digestive ly healthy

although if you eat too much of it you

can feel kind of bloated and stopped-up

cows on the other hand can digest

cellulose which is why they chew on

grass and that's a good type of

nutrition for them and termites they can

chew on wood because they have the

enzyme that can break up the strong

cellulose fibres that make the woody

tissue the tough parts of wood tree

trunks and what have you chitin if you

look at this diagram is a little bit

different than cellulose

we've got chains of monosaccharides here

but the other key thing to look for is

that there are these nitrogen's now I

don't know if you can see this so I'm

going to zoom in here and I know it gets

fuzzy but that right there is an N

alright there's another end right there

if you zoom in there see and tighten

again that's the structural

polysaccharides in the exoskeletons of

insects and crustaceans and even in the

cell walls of some fungus like you know

mushrooms that is so for the most part

we also can't eat chitin but some

materials like soft-shell crab chitin

exoskeleton there aren't so many cross

linkages with the proteins and built in

between those nitrogen cross linkages so

the tightness material in the

exoskeleton of softshell crabs is not as

tough so we can chew it up and and

digest that but if you like eating

lobster or shrimp you know you can't eat

the shell that's just too tough for you

to eat so that'll be the end of our

screencast segment 3 here for

carbohydrates you can look forward to

screencast segment for next time

as always if you have any questions or

concern please talk to mr. gales or me

mr. workman if you have any questions

thanks everybody