lecture 15.2 definitions

Carbohydrates

Carbohydrates

Member of large class of naturally occurring polyhydroxy ketones and aldehydes.

Monosaccharide

A carb that can’t be chemically broken down into smaller sugar by hydrolysis with aqeous acids (Composed of 3-7 carbons).

Disaccharide

A carb composed of 2 monosaccharides.

Polysaccharide (complex carb)

Polymer of monosaccharides

Aldose

A monosaccharide that contains an aldehyde group

Ketose

A monosaccharide that contains a ketone group

-ose =

carb

aldohexose

starts with an aldehyde, 6 carbons

ketohexose

starts with a ketone, 6 carbons

D and L isomers (enantiomers)

Monosaccharides that are mirror images of one another.

_____ of all monosaccharides is the most prevalent in nature

D form

Diastereoisomers

Monosaccharides that are stereoisomers but are not mirror images

Anomers

Cyclic sugars that differ in positions of substituents at the hemiacetal carbon.

The ____ form of glucose is the most prevalent in nature.

Beta

D-isomer

A monosaccharide with the OH group on the chiral carbon atom farthest from the carbonyl group pointing to the right. (think derecha)

L-isomer

A monosaccharide with the OH group on the chiral carbon atom farthest from the carbonyl group pointing to the left.

Anomeric carbon

Carbon atom in cyclic sugar that is bonded to two separate oxygen atoms.

Oxidation of Carbs

Carbs that are oxidized are called reducing sugars because they reduce other chemicals.

Carb rxn with alcohols

Monosaccharides are cyclic hemiacetals that react with alcohol to form acetals, which occurs in the formation of glycosides, disaccharides, and polysaccharides.

Formation of phosphate alcohols

Alcohols on monosaccharides can react with PO3²- to form high energy phosphorylated intermediates in metabolism.

Oxidation of a monosaccharide

Aldehydes become carboxylic acids, the anomeric carbon is not involved in a glycosidic bond.

Oxidation of a ketose

Ketoses can be considered reducing sugars

Glucose oxidase test

Measures the amount of glucose in blood and urine through the oxidation of glucose.

Glycosidic bond

A bond between the anomeric carbon of a monosaccharide and -OR group (acetal group).

Maltose Alpha - 1,4 linkage (Disaccharide)

A glycosidic bond between the Anomeric carbon in the C1 position of one monosaccharide, whose hydroxyl group is in the alpha position and the hydroxyl group on C4 of another monosaccharide.

Lactose Beta 1, 4 Linkage (Disaccharide)

A glycosidic bond between the anomeric carbon in the C1 position of one monosaccharide whose hydroxyl group in the beta position and the hydroxyl group off the C4 of another monosaccharide.

Galactose and Glucose are what kind of isomer?

Diastereoisomer

Is Sucrose a reducing sugar?

NO

What is the BAD bacteria involved in tooth decay?

streptoccocus mutans

What is the GOOD teeth bacteria?

streptoccocus sanguis

Role of Carbs in the body

• source of energy

• become phosphorylated to make high energy intermediates in metabolism

• function as an anticoagulant and joint lubricant

• determines blood type by attaching to proteins on rbcs

• form receptors by attaching to proteins and lipids on cell surface

Role of carbs in environment

• form bacterial cell walls and exoskeleton of invertebrates

• form polysaccharides that provide structural stability in plants

CHITINS

polysaccharide second in abundance in the natural world, found in joints, tendons, and cartilage as lubricant

HEPARIN

polysaccharide associated with connective tissue

anticoagulant

binds tightly to a blood clotting factor and is highly charged

Glycoproteins

Sugars covalently bonded to proteins, linked to proteins by N or O

Which substances determine blood types?

Glycolipids and Glycoproteins on the surface of RBCS

Type O blood

3 diff color sugars

Type A blood

3 diff color sugars, with a unique 4th yellow sugar hanging off the middle sugar

Type B blood

3 diff color sugars, teal 4th sugar hanging off middle (also teal) sugar

Cellulose (polysaccharide)

• Most abundant in nature

• composed of beta-D-glucose units linked by beta-1,4 glycosidic bonds

• fibrous substance that provides plants structure

• humans cannot hydrolyze (digest) it

Amylose (plant starch)

• fully digestible

• 20% of plant starch

• polymer of alpha1,4-D-glucose

Amylopectin (plant starch)

• 80% of plant starch

• polymer of alpha 1,4-D-glucose with branches of alpha 1,6-D-glucose

• 10^5 glucose/molecule

Glycogen

• Short term energy storage,

• stored in liver and muscles

• same structure as amylopectin but more branches and bigger

• 1lb holds 2lb water

An aldose is a carb that:

begins with an aldehyde group and ends with an alcohol group.

A carbohydrate is an L-isomer, if, in its fischer projection, the –OH group is positioned on the ________.

left side of the last chiral carbon

Which of the following statements is true?

If the -OH group bound to the anomeric carbon is located below the ring structure of the monosaccharide, then the saccharide is in the alpha configuration.

The alpha or beta configuration of a glycosidic bond is determined by the configuration of the _______.

the anomeric carbon involved in the glycosidic bond

What is the configuration of the glycosidic bond in heparin?

Alpha-1,4

Cellulose is made up of repeating units of _______that are linked by______ glycosidic bonds and humans ______ digest.

beta-D-glucose, beta-1,4 cannot

Glycogen is made up of repeating units of ______ that are linked by ______glycosidic bonds and humans _____ digest.

alpha-D-glucose, alpha-1,4, can