CARBOHYDRATES (definition)

Definition of Terms

Are polyhydroxy ketones (ketose) or polyhydroxy aldehydes (aldose) or compounds that can be hydrolyzed from them (CH2O)n; Cn(H2O)y; carbon hydrates; sometimes referred also as sugars.

Carbohydrates

Widely distributed in plants and animals (cell walls, cell membranes, nucleotides, coenzymes)

Carbohydrates

Function of carbohydrates

Storage form of metabolic fuel

Function of carbohydrates

Structural function

Most abundant in nature, no nutritive value, form the cell wall of plants

Cellulose

Exoskeleton of crustaceans

Chitin

Found in the cell wall of bacteria

Peptidoglycan

Transport function

Glycoproteins

Follicle-stimulating horone that regulates the development, growth, pubertal maturation, and reproductive process

Regulatory function

Catalytic function

Ribonuclease

Anti-viral function

Interferon

Protective/Lubricating functions

Hyaluronic acid & mucin

Most abundant acid mucopolysaccharide found in connective tissue, vitreous humor of eye, synovial fluid

Hyaluronic acid

Other biological functions #1

Biological specificity of animal cell membrane e.g. blood typing

The 4 blood types

A, B, AB, O

Is based on 3-4 monosaccharides attached to a membrane protein of red blood cells

Blood type

N-actetyl-D-glucosamine--D-galactose--L-fucose

Blood type O

N-actetyl-D-glucosamine--D-galactose--L-fucose--N-acetyl-D-galactsamine

Blood type A

N-actetyl-D-glucosamine--D-galactose--L-fucose--D-galactose

Blood type B

Other biological functions #2

Components of clotting proteins

An anti-clotting agent present in the body

Heparin

Precursors which initiate biological processes for biosynthesis of:

Purine, pyrimide, nucleotides, vitamin c, and certain amino acids

Simplest form of sugar which canniot be further hydrolyzed; building blocks of carbohydrates

Monosaccharides

Sweet tasting, with varying relative sweetness

Monosaccharides

Polar compounds with high melting points

Monosaccharides

Solid at room temp, very soluble in water

Monosaccharides

According to the number of carbons in monosaccharides

3-triose

4-tetriose

5-pentose

6-hexose

7-heptose

Monosaccharides with an aldehyde group

Aldose (R-CHO)

Monosaccharides with a ketone group

Ketose (R-CO-R)

Six-membered ring resembling pyran; aldoses

Pyranose

Hexagon ring

Pyranose

Five-membered ring resembling furan; ketoses

Furanose

Pentagon ring

Furanose

Polymers made up of 2-10 monosaccharides

Oligosaccharides

Has 2 monosaccharides

Disaccharides

Polymers more than 10 saccharide units

Polysaccharides

One kind of monosaccharide

Homopolysaccharides

Homopolysaccharides

1. Starch-glucose
2. Glycogen-glucose
3. Dextrin-glucose
4. Cellulose-glucose
5. Dextran-glucose
6. Inulin-fructose

Two or more kind of monosaccharides

Heteropolysaccharides

d-glucoronic acid + d-glucosamine + acetic acid

Hyaluronic acid

Six sugar residues + N-acetyl-D-glucosamine + D-iduronate

Heparin

Sugars added with other substituents aside from OH

Derived Carbohydrates

Derived Carbohydrates

a. Sugar acid

b. Sugar alcohol

c. Amino sugar

d. Deoxy sugar

e. Phosphorylated sugar

Carbohyrates with free aldeyde or ketone group

Reducing sugars

Carbohydrates without free aldehyde or ketone group

Non-reducing sugars

Sucrose and all polysaccharides are ________

Non-reducing sugars

An optical isomer which rotates the beam of polarized light to the right or clckwise and indicated by a + sign or small letter d

Dextrorotatory

An optical isomer wich rotates the beam of polarized light to the left or counter-clockwise and indicated by a - sign or small letter l

Levorotatory

(+) glucose or d-glucose

Dextrorotatory

(-) glucose or l-glucose

Levorotatory

Used to measure the optical rotation of molecules in solution

Polarimeter

The enantiomer with the OH group on the right (dextro) side of the chiral carbon farthest from the carbonyl group

D

The enantiomer with the OH group on the left (levo) side of the chiral carbon farthest from the carbonyl group

L

Most biologically active monosaccharides are

D isomers

Most monosaccharides occuring in mammals are of the D-configuration and enzymes responsible for their metabolism are specific for this configuration.

D isomers

Stereoisomers that differ in configuration around an anomeric carbon of a cyclic structure or ring structure

Alpha & Beta anomers

The OH is written below the anomeric carbon

Alpha (α)

The OH is writen above the anomeric carbon

Beta (β)

Most sugars are of _______ since our body can only utilize those of this anomers except in some cases.

α-anomers

The anomeric carbon is C-1 and is obtained by cyclization of an aldehyde and an alcohol group

Pyranose

The anomeric carbon is C-2 and is obtained by cyclization of a ketone and an alcohol group

Furanose

Stereoisomers that differ in configuration around a single carbon atom of a linear structure differ only in 1 carbon atom

Epimers

D-glucose in the liver by a specific enzyme called ___________

Epimerase

Straight chain or open chain structures

Fischer projection

Ring or cyclic structures; hemiacteals and hemiketals

Haworth projection

The product of the addition of an alcohol to the carbonyl group of an aldehyde

Hemiacetal

The product of the addition of an alcohol to the carbonyl group of a ketone

Hemiketal

Boat and chair structures

Newman projection

General rule to translate fischer to haworth projection #1

Classify given sugars as aldose (pyranose) or ketose (furanose)

General rule to translate fischer to haworth projection #2

Detern whether the given sugar is α-anomer or β-anomer. At the anomeric carbon the α form is indicated by the -OH being written below the plane; β from has the -OH above the plane.

General rule to translate fischer to haworth projection #3

The groups on the right side of the fischer projection are written below the plane in the haworth projection. Those on the left side are written above the plane. Applicable for C2, C3, C4, for aldoses; C3, C4 for ketoses.

General rule to translate fischer to haworth projection #4

Exception to the rule 3 occurs at carbon 4 in pentoses and at carbon 5 in hexoses because of the nature of the reaction occuring there.

General rule to translate fischer to haworth projection #5

In both projections the CH2OH group in C6 for adoses and C1 & C6 in ketoses, which has no chiral carbon, is written as a unit.

__________ like fructose from five-membered rings with two anomers.

Ketohexoses

Most important of all monosaccharides

D-glucose \[74.3\]

Usually found in the bloodstream and in the tissue fluids thus known as blood sugar

D-glucose \[74.3\]

Commercially known as dextrose because it is mostly dextrorotatory

D-glucose \[74.3\]

Two hormones, insulin and glucagon, have important roles in keeping it within normal range

D-glucose \[74.3\]

If the blood glucose exceeds 100 mg/dL and remains high, _________ may be indicated

Hyperglycemia

An example of a disease that can cause hyperglycemia is ________, which occurs when the pancreas is unable to produce sufficent quatities of insulin.

Diabetes mellitus

When a person is _________, the blood glucose level rises and then decreases rapidly to levels as low as 70 mg/dL

Hypoglycemic

The only ketose sugar encountered in biochemistry. Sweetest of the common sugars.

D-fructose\[173.3\]

Also known as levulose because it is strongly levorotatory in solution

D-fructose\[173.3\]

The _______ can convert D-fructose to D-glucose

Liver

\-An aldose not found fee in nature but is rather widely distributed in the forms of polysaccharide called mannans

\-found in silage, pineapples, important in exprosives

\-the only carbohydrate with a bitter taste

D-mannose\[0.0\]

\-The most common occurence is in lactose (sugar milk); brain sugar found in brain and nerve tissue.

\-Necessary for the synthesis of lactose in milk; made in the mammary glands

D-galactose\[32.1\]

Is an important dietary carbohydrate that is found in the milk of all mammals.

Lactose

Lactose digestion occurs in the small intestine, where the enzyme lactase (β-galactosidase) hydrolyzes the molecule to form galactose and glucose. Many adults, including most blacks and almost all Asians, have a low level of this enzyme.

\- The lactose in the milk they drink travels through the small intestine to the colon mostly undigested. In the colon, bacterial fermentation of the lactose produces large quantities of CO2, H2, and irritating organic acids. This results in bloating, flatulence, abdominal pain, and diarrhea from drinking milk. The diarrhea results from fluids moving into the small intestine in response to the osmotic pressure from the undigested lactose.

Lactose intolerance

A more serious disease involving lactose is ___________. More than one out of every 20,000 children in born with a deficiency in certain enzymes necessary for the metabolism of galactose. Their bodies can hydrolyze lactose to form glucose and galactose, but they are unable to metabolize the galactose. Thus producing the toxic metabolic derivative D-GALACTITOL (D-DULCITOL).

\- As the galactose accumulates in the blood and urine, the body converts it to the other compounds that can lead to cataract formation and mental disorders. In more severe cases, some children have died from liver damage resulting from the building of galactose.

Galactosemia

When this reaction occurs between two monosaccharides, the bond that joins them together is called a _____________.

\
The ___________ joining the two rings ca be alpha or beta.

Glycosidic linkage

______________ cleaves the C-O glycosidic linkage and forms two monosaccharides.

Hydrolysis

\- α-1,4 glycosidic linkage is present - The most common reducing disaccharide

\- Not found as free substance but as a constituent of polysaccharides, starch and glycogen; MALT SUGAR

\- Used as malt extract, sweetener and as a fermentative reagent

\- Common ingredient in baby foods

\- Hydrolysis of ________ yields 2 glucose molecules

Maltose\[32.5\]

β-1,4 glycosidic linkage is present

\- MILK SUGAR

\- Its main function is to furnish the galactose necessary for the synthesis of glycolipids of brain and nervous tissue

\- Hydrolyzed by LACTASE; makes up to 4% lactose in cow’s milk;

Lactose\[16.0\]

is the disaccharide in milk; it consists of 1 galactose ring and 1 glucose ring joined by a 1→4-β-glycosidic bond

Lactose\[16.0\]

\-α-1,2 glycosidic linkage

\- Commonly called as CANE SUGAR and sometimes SACCHAROSE

\- The ordinary sugar used in cooking and on the table; TABLE SUGAR

\- A non-reducing sugar

Sucrose\[100.0\]

_________is a disaccharide consisting of 1 glucose ring and 1 fructose ring.

________ is very sweet, but contains many calories.

\- To reduce caloric intake, many artificial sweeteners have been developed.

Sucrose

\- Storage form of energy in plants

\-tasteless

\- One of the most important constituents of the human diet, making about 50-70% of the solid substances of most of the cereals

Starch

300-500 glucose units, tastelss

Amylose

Up to 100,000 glucose units; branching every 25-30 glucose units, tasteless

Amylopectin

\- also called ANIMAL STARCH

\- branched chain -1,4 and -1,6 glycosidic linkages in every 12-18 glucose units; 3x more highly branched than amylopectin;

\- much larger with up to 1,000,000 glucose units - found mostly in the liver as storage material and in the muscle as source of energy.

\-tasteless

Glycogen