carbohydrates and polysaccharides

What are carbohydrates made of

Carbon oxygen and hydrogen

What is the most common carbohydrates minimal formula

Cn(H2O)n

What is the other name of carbohydrates

Saccharides, sugars

Carbohydrates are major sources of energy, how do we take them

Intake from diet but mammals are also able to synthesize from small MW metabolites,

How do plants synthesize sugars

From CO2 and energy in the form of radiation

Synthesis is an overall reduction reaction, respiration is oxidation

What are the different types of carbohydrates

Monosaccharides, the simplest ch

Disaccharides, two covalently linked monos.

Polysaccharides, many covalently linked monos

What is the structure of a monosaccharides

In simple cases it contains a carbon chain, an aldehyde (aldose) or ketone (ketose) group, and hydroxyls on each carbon atoms except the carbonyl

Name these monosaccharides

Fisher projections

Which carbon atom decides whether it’s L or D

The one chiral carbon that’s furthest away from the most oxidized C atom (chiral carbon)

Are d-glucose, d-fructose and d-galactose enantiomers (mirror image of one another)?

No they are stereoisomers (Same formula different structure)

VERY IMPORTANT IN THE EXAM

YOU SHOULD SAY IT’S A POLYMER OF D-GLUCOSE NOT JUST GLUCOSE

What is the most common hexose

D-Glucose

Where is D-Glucose found in

Fruits, vegetables, corn syrup and honey

What is D-Glucose also known as in the body

Dextrose and blood sugar

What is the D-Glucose the building block of

The disaccharides; sucrose, lactose and the polysaccharides such as cellulose and glycogen

What is galactosemia

High galactose in blood

What is the formula of d-galactose

It’s an aldohexose with the formula C6H12O6

D-galactose is the building block of what

lactose

Which monosaccharide is important in the cellular membranes of the brain and nervous system

D-galactose

What happens in the condition of galactosemia

the enzyme needed to convert d-galactose to d-glucose is missing so galactose accumulates in the blood and tissue

What can galactosemia cause

The accumulation of galactose in the blood and tissue can lead to cataracts, mental retardation, failure to thrive and liver disease

D-fructose formula

Ketohexose with the formula C6H12O6

What is the sweetest carbohydrate

D-fructose

How can we obtain d-fructose

By the hydrolysis products of sucrose (so fructose isn’t the only building block of sucrose but one of them)

How can we obtain high-fructose corn syrup (HFCS)

By using an enzyme to break down sucrose to glucose and fructose

Formula of d-ribose

Aldopentose with the formula C5H10O5

What is the d-ribose component of

Ribonucleic acid (RNA) molecules

How do we obtain d-ribose

It is reduced from 2-deoxy-d-ribose which is part of the deoxyribonucleic acid (DNA) molecules

What is the difference between d-ribose and 2-deoxygenated-d-ribose

What are the reactions that monosaccharides can perform and they react as which form

-reduction

-oxidation

-aldol reaction

-reaction with amines

-formation of acetals and hemiacetals

They react as aldehydes or ketones

Reactions they can enter if they have one or more hydroxyl group and what they act as

-oxidation (Aldehydes only)

-water elimination

-formation of esters

They react as alcohols

Aldoses and ketoses ar in equilibrium between the open chain and cyclic forms. The reaction is reversible

How do we get cyclic forms in aldoses and ketoses (monosaccharides)

From an intermolecular reaction between the carbonyl and a -OH group (the different ends of the monosaccharide open chain)

Cyclic hemiacetals yielding a five or six membered ring are stable

Self explanation: when the carbonyl group reacts with the hydroxy group on the same sugar a cyclic structure is produced and it’s called a hemiacetal.

Why do we usually find sugar in a cyclic structure

Because cyclic hemiacetals yielding a five or six membered ring are stable

What are the 5-membered and 6-membered hemiacetals called

Furanose (5-membered)

Pyranose (6-membered)

What is the difference between alpha and beta-d-glucose

alpha= -OH down

Beta= -OH up

What is an anomer

A cyclic stereoisomer of a carbohydrate with isomerism involving only the arrangement of atoms or groups at the aldehyde or ketone position (meaning that it’s a stereoisomer where the only difference is on the anomeric carbon which is the carbonyl group’s carbon)

Why is the chair conformation important

-minimizes angle strain

-minimizes torsional strain

-is the lowest energy shape

(Minimize steric hindrance)

What is mutarotation

Mutarotation is the spontaneous interconversion of alpha and beta anomers of sugar in solution via the open chain form causing a gradual change in optical rotation until equilibrium is reached

Mutarotation in fructose (ketose)

What are the common monosaccharides

1- D-Glucose (6C)

2- D-Galactose (6C)

3- D-Fructose (6C)

4- D-Ribose (5C)

What are the conditions for the oxidation of monosaccharides

1- Monos. Are mostly found in cyclic forms in solutions but the small amount of the open chain form can be oxidized

2-have an aleyhe group with adjacent hydroxyl group that can be oxidized to carboxylic acid

Can ketoses undergo oxidation

No normally they can’t BUT intermolecular rearrangments make monosaccharides such a s fructose oxidizable

Are d-glucose and d-galactose stereoisomers

Yes, d-fructose is a structural isomer since it’s a ketose and d-ribose has 5 carbon atoms

What can be an oxidizing agent for an aldose

Benedict’s solution

Reduction of monosaccharides

What are alditols

Sweeteners with less calories

How are disaccharides formed

they are formed through the conensation of two cyclic monosaccharides

Hemiacetals tam anlamadım ama özetle bu

İyi çalış bu slaytı

20. Slayt

Two disaccharides

Lactose and sucrose

What is lactose found in

Breast milk

Hydrolysis of lactose

Is hydrolyzed by lactase in the intestine to galactose an glucose that are absorbed by the villi

How does lactose intolerance develop

Lactase enzyme is dose-inducible so if absent or low activity, lactose intolerance develops

What are lactose and sucrose composed of

Lactose= beta-D-galactose and alpha-D-glucose

Sucrose= alpha-D-glucose and beta-D-fructose

Why can’t sucrose undergo mutarotation

Because both its anomeric carbons are involved in the glycosidic bond

Why can’t sucrose undergo oxidation

Because it has no free aldehydes or ketone group

GLUCOSE VE SUCROSE NASIL OLUŞUR ŞEKİLLERİ O FORMÜLLERİ FALAN BİL

Yani soruğunda yazabil

The chemistry of taste

What is a polysaccharide

Many monos. Joined together via O-glycosidic bond

What is a homopolysaccharide

Single repeating unit and zıttı da heteropolysaccharide

What is the formation of specific O-glycosidic bonds directed by

It’s directed by enzymes that not only catalyze the condensation reaction but also direct the specific coupling between one anomeric carbon and one specific hydroxyl

Why is the most common homopolysaccharide is glucose polymers

Because organisms fight har for their energy source and when an excess is available it is store in a polymeric molecule. When energy is scarce, individual units can be removed from polymer to extract the required energy (also for structural reasons like cellulose)

4 polysaccharides

Amylose

Amylopectin

Cellulose

Glycogen

Amylose:

• poly-alpha (1,4) glucose

• Linear chains usually between 300-600 but up to 4000 repeating units

• Found in plants, about 20-30% starch

How is amylose broken down into smaller oligosaccharides

Through hydrolysis catalyzed by enzymes called alpha-amylases (in the saline secrete by the pancreas)

Amylopectin:

• poly-alpha (1,4) glucose with alpha(1,6) branches

• Branching occurs every 30 glucose units

How does an amylopectin form starch

Amylopectin associates with amylose via non-covalent hydrogen bonding interactions to form starch

Are amylose amylopectin cellulose glycogen all homopolysaccharide

Yes

Cellulose:

• Poly-beta(1,4) glucose

• N is between hundreds and thousands

• Cotton fiber is 90% cellulose

What is the cell wall of green plants composed of

Cellulose

Is cellulose digestible

No, most animals lack the enzyme required for the hydrolysis of the beta(1,4) glycosiic bond

How do animals store glucose

Animals store glucose in a polymer called glycogen

Glycogen:

• poly-alpha(1,4) glucose with alpha(1,6) branches

• Branching occurs every 8-12 residues

Which two homopolysaccharide are branched

Amylopectin and glycogen (glycogen has more frequent branching)

Why branching on glycogen?

When glucose is needed, monosaccharides are detached at the non-reducing end of the chain

What are the products when a hemiacetals reacts with an alcohol

Acetal and water

The slide explains that glycosidic bond formation is a condensation reaction that is thermodynamically unfavorable in water, so it does not occur spontaneously. To make polysaccharides, cells use activated sugar nucleotides (like UDP-glucose), whose high-energy phosphoanhydride bonds provide the energy needed to drive glycosidic bond formation.

Briefly,

Glycosidic bonds don’t form spontaneously in water — cells must spend nucleotide energy to make them.

Homopolysaccharides are typical energy storage molecules, what are heteropolysaccharies’ functions

• structural

• Increasing solubility of proteins

• Shielding proteins from the immune system

• Stabilizing extracellular proteins

• Specific function, such as anticoagulants

• Determine medically-important features, such as blood groups

Glycans (polysaccharides conjugated to other molecules) can associate with proteins to yield glycosylated proteins

Which kind of protein undergoes glycosylation

extracellular proteins, produced inside the cell and the secreted or translocated to the cell membrane

What is N-glycosylation

Glycans attached at the N (nitrogen) atom of Asn (Asparagine) residues that are found in consensus sequences

What is O-Glycosylation

Glycans attached to Ser or Thr residues. Very heterogeneous (bura da yine ser ve thr nin oksijenine bağlı diye o)

What are glycosaminoglycans (GAGs) Aka mucopolysaccharides

linear polymers of repeating disaccharides (ama galiba glycan olanlar)

What is the disaccharide composed of In glycosaminoglycans

Uronic acid (sugar with -COOH function) and amino sugar (sugar with amino group replacing one of the -OH)

What is the exception to the previous question

Keratin where galactose is in place of the acid

How can sugars be modified

By formation of sulfate esters

It means that a hydroxyl group (–OH) on a sugar is chemically modified by attaching a sulfate group (–SO₃⁻) to it. Yani o eklenirse sugar olmaktan çıkıyo diye anladım

Structural function of glycosaminoglycans

Function is mostly to maintain flexibility, composition of connective tissue, act as lubricants for joints

Uronic acids and amino sugars in GAGs

Where are GAGs synthesized

Golgi apparatus

Anlamadım

What are proteoglycans

heavily glycosylated proteins with one or more GAGs attached to to the core polypeptide

What is the principal component of the extracellular matrix in animals

Proteoglycans

Difference between glycoproteins and proteoglycans

Glycoproteins are mostly protein with short, branched carbohydrates; proteoglycans are mostly carbohydrate with long glycosaminoglycan (GAG) chains attached to a small protein core.

What is cartilage composed of (Kıkırdak)

Collagen GAGs and proteoglycans

Bu sunumun 24 ve 25. Sayfalarını hiç anlamaım bak

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