CHEM 1114 Module 7

guidlines to identify chiral center

-A carbon atom involved in a multiple bond (double or triple bond) cannot be a chiral center -The commonly encountered entities CH3 and CH2 in a structural formula never involve chiral centers -Carbon atoms in a ring system, if not involved in multiple bonding, can be chiral centers

carbohydrate

-a polyhydroxy aldehyde, a polyhydroxy ketone, or a compound that yields polyhydroxy aldehydes or polyhydroxy ketones upon hydrolysis. The carbohydrate glucose is a polyhydroxy aldehyde, and the carbohydrate fructose is a polyhydroxy ketone. -sugars and polymers of sugars

Cellobiose

-a reducing sugar -beta (1-4) linkage

amylopectin in starch

-branched -alpha (1->6) linkages -accounts for 80-85% the remaining of the starch.

amino sugar formation

NH2 replaces an —OH group in an amino sugar -suffix -amine -beta-D-glucoamine

Reduction of Monosaccharides

The reduction of the carbonyl group in monosaccharides results in an alcohol replacing the aldehyde group

The three common naturally occurring amino sugars are all D-stereoisomers: T or F

True -D-glucosamine, D-mannosamine, and D-galactosamine.

a strong oxidizing agent results in

a carboxylic acid replacing the aldehyde on top and the CH2OH on bottom

simple carbohydrates

a dietary monosaccharide or dietary disaccharide -Simple carbohydrates are usually sweet to the taste and are commonly referred to as sugar

chiral center

a handedness generating carbon atom; an atom in a molecule that has 4 different groups bonded to it

left handed molecule

a left handed molecule is denoted by L or S and means that the —OH group on the highest numbered chiral carbon is on the left side

chiral molecule

a molecule that is not superimposable on its mirror image

Achiral molecules

a molecule whose mirror images are superimposable

Homopolysaccharide

a polysaccharide in which only one type of monosaccharide monomer is present.

right handed molecule

a right handed molecule is denoted by R or D and means that the —OH group on the highest numbered chiral carbon is on the right side

Fischer projection

a two dimensional representation showing the spatial arrangements of groups about chiral atoms in molecules

reducing sugar

an anomeric carbon (hemiacetal) that has an —OH and —H bonded so it can open up

aldehydes and ketones in a fisher projection become ____________ carbons in the haworth projections

anomeric

glycan

another name for a polysaccharide

stereocenter

bonded to four different things

consumption of what leads to insulin resistance

carbohydrates

what is insulin resistance

cells are less responsive to insulin failing to lower blood sugar

Heteropolysaccharides

composed of two or more monosaccharide types

refined sugar

sugar that has been separated from its plant source, obtained from sugar cane and sugar beets

natural sugars

is a sugar naturally present in whole foods. -Milk and fresh fruit are two important sources of natural sugars.

what makes high fructose corn syrup preferable to sucrose

it is cheaper to grow corn instead of cane sugar and it has a longer shelf life

complex carbohydrates

polysaccharides -The main complex carbohydrates are starch and cellulose, substances not generally sweet to the taste.

glycoside formation

reaction between an alcohol and a monosaccharide to produce a disaccharide

mirror image

reflection of an object in a mirror

storage polysaccharides

starch and glycogen

humans can break down

starch, not cellulose

enantiomers

stereoisomers that are non-superimposable mirror images of each other

fancy biochemical name for table sugar

sucrose

fructose + glucose

sucrose

a ~OH means

that we do not know the direction of the first carbon molecule (aldehyde or ketone)

which is worse, HFCS or sucrose

they are molecularily the same

what makes high fructose corn syrup high fructose corn syrup?

they change the balance: there is 55% fructose and 45% glucose

On a fischer projection, if an —OH is on the left, it is drawn on the haworth projection going

up

why is cellulose added to bread

we can't digest cellulose. cellulose adds "bulk" and fiber to the bread but not calories

which foods have high glycemic index

white bread, soda

The D or L form of a monosaccharide is determined by the position of the

—CH2OH‍ group on the highest-numbered ring carbon atom. -In the D form, this group is positioned above the ring. -In the L form, which is not usually encountered in biochemical systems, the terminal —CH2OH ‍ group is positioned below the ring.

Alpha or beta configuration is determined by the position of the

—OH group on carbon 1 relative to the —CH2OH ‍ group that determines D or L series. -In a beta configuration, both of these groups point in the same direction; in an alpha configuration, the two groups point in opposite directions.

beta anomer

the —OH on carbon 1 is pointing up

alpha anomer

the —OH on the carbon 1 is pointing down

glycogen

-It is the glucose storage polysaccharide in humans and animals -all glycosidic linkages are of the alpha type, and both (1->4) and (1->6) linkages are present. -Glycogen is about three times more highly branched than amylopectin

maltose

-Maltose is a reducing sugar because the glucose unit on the right has a hemiacetal carbon atom (C-1). Thus this glucose unit can open and close; it is in equilibrium with its open-chain aldehyde form -alpha (1-4) linkage

Oligosaccharides

-is a carbohydrate that contains three to ten monosaccharide units covalently bonded to each other. -Complete hydrolysis of an oligosaccharide produces several monosaccharide molecules

Polysaccharides

-is a polymeric carbohydrate that contains many monosaccharide units covalently bonded to each other. -Polysaccharides, like disaccharides and oligosaccharides, undergo hydrolysis under appropriate conditions to produce monosaccharides.

sucrose

-nonreducing sugar -Two monosaccharides in D-sucrose are alpha-D-glucose and beta-D-fructose and the glycosidic linkage is alpha, beta (1-2) glycosidic linkage.

lactose

-reducing sugar -Lactose is made up of beta-D-galactose and D-glucose and joined by beta (1-4) glycosidic linkages

amylose in starch

-unbranched -glucose units are connected by an alpha (1->4) glycosidic linkage. -usually accounts for 15-20% of the starch;

Oxidation of Monosaccharides

-when a monosaccharide is oxidized in tollens or benedict's solution (mild oxidizing agents) a carboxylic acid forms in place of the aldehyde group -when a monosaccharide with an aldehyde group undergoes reduction in the presence of an acidic environement, the aldehyde group is replaced with an alcohol group

what is the role of insulin in sugar management

-when you eat and sugar levels rise, insulin is secreted into your blood and prompts muscle and fat cells to let glucose in. -starts the conversion from sugar to energy

what distinguishes polysaccharides from each other

1. the identity of monosaccharide 2. length of polymer chain 3. type of glycosidic linkages between monomer units 4. the degree of branching of the polymer chain

Polysaccharides have ____ linked sugars

10+

complex carbohydrates have __ or more simple sugars strung together

3

Oligosaccharides have __ linked sugar

3-10

furanose

5 membered ring

pyranose

6 membered ring

ketose

A carbohydrate whose carbonyl group is a ketone

aldose

A carbohydrate whose carbonyl group is an aldehyde

hemiacetal

A functional group that contains a carbon atom bonded to one -OR group, one -OH group, an alkyl chain, and a hydrogen atom.

starch

A storage polysaccharide in plants consisting entirely of glucose.

starch

A storage polysaccharide in plants consisting entirely of glucose. -alpha linkage

glycosidic linkage

Bond between two monosaccharides resulting from the reaction between the hemiacetal carbon atom —OH group pf one monosaccharide and the —OH on the other monosaccharide

general formula for carbohydrates

C6H12O6 Cn(H2O)n CnH2nOn -NOT ALL CARBOHYDRATES HAVE THIS FORMULA

cellulose

Carbohydrate component of plant cell walls that helps maintain structure -beta linkage

sterioisomer

Compounds with the same structural formula but with a different arrangement of the atoms in space.

fructose

alpha-D-fructose

ribose

alpha-D-ribose

monosaccarides (monomers)

contains a single saccharide unit -glucose -fructose -galactose is a carbohydrate that contains a single polyhydroxy aldehyde or polyhydroxy ketone unit.

disaccharide

contains two monosaccharides that have joined during a dehydration reaction -fructose + glucose = sucrose -glucose + glucose = maltose Hydrolysis of a disaccharide produces two monosaccharide units.

what is high fructose corn syrup made from

corn

nature prefers

cyclic, right handed molecules

On a fischer projection, if an —OH is on the right, it is drawn on the haworth projection going

down

foods high in starch are digested

easily

which foods have low glycemic index

eggs, cheese, meats

where does fructose get its name

fruit

Superimposable mirror images

images that coincide at all points when the images are laid upon each other

nonsuperimposable mirror images

images where not all points coincide when the images are laid upon each other

glucose + glucose

maltose

anomer

monosaccharides that differ only in the positions of the substituents on the anomeric (hemiacetal) carbon -carbon 1 is the anomeric carbon

what is lactose intolerance

occurs when a person does not have enzyme lactase to break down lactose

the highest numbered —OH on a carbon

oxygen that closes the ring

glycemic index

the amount of particular food raises the sugar level in your blood

what is insulin sensitivity

the degree to which a unit of insulin lowers blood sugar

phosphate ester formation

the hydroxyl group of a monosaccharide reacts with a phosphate to create a phosphate ester

CH2OH going down means

the molecule is left-handed (L or S)

CH2OH going up means

the molecule is right-handed (D or R)

anomeric carbon

the new chiral center formed in ring closure; it was the carbon containing the carbonyl in the straight-chain form