Carbohydrates

glycosidic linkages can occur at which # carbons on carb structure?

1, 6 1, 4 1, 2

# of stereoisomers of a compound can be found by:

2^n, where n=#chiral carbons

D vs L sugars

All D sugars have their -oh of their highest priority chiral centers on the right while L will have it on the left.

glycogen is highly branched. how?

stored by animals. linked by alpha 1,6 glycosidic linkages (1 link per 10 glucose molecules making it highly branched)

most basic structure of monosaccharide

glyceraldehyde, the most simple aldose - an aldotriose (carbs with aldehyde)

why are monosaccharides with a hemiacetal ring a reducing sugar?

hemiacetals can be oxidized, so it can act as a reducing agent

disaccharides and polysaccharides are formed as a result of ___ bonds between monosaccharides, as a result of them reacting with alcohols.

hemiacetals react with alcohol to form acetals. the resulting CO bonds are called glycosidic bonds.

What property is associated with the existence of glycine as a dipolar ion in aqueous solution?

high dipole moment Polarity in neutral molecules results from an uneven distribution of electron density, which can arise from separation of unlike charges. This occurs in zwitterions and in ylides. In addition, molecules that contain strongly electron-withdrawing or electron-donating substituents are highly polar and possess correspondingly high dipole moments.

What type of reaction forms glycosidic bonds?

hydrolysis

General formula of fatty acid and corresponding fatty acid salt

A fatty acid would have the general formula Rn—CO2H. The corresponding fatty acid salt would have the general formula Rn—CO2- Na+.

Saponification is a procedure that involves the basic hydrolysis of esters. For example, when a triacylglycerol is saponified with NaOH, the products are glycerol (1,2,3-trihydroxypropane) and the salts of fatty acids (soaps). Researchers saponified a pure triacylglycerol and discovered that four fatty acid salts were produced instead of three. In order to identify the four salts, the researchers converted the salts into a mixture of fatty acid esters and analyzed the resulting mixture by gas chromatography. Which of the following is the most plausible explanation for the fact that saponification of the triacylglycerol would result in four different fatty acid salts instead of three? The triacylglycerol molecule consisted of four different fatty acid units. Glycerol was transformed into a fatty acid salt under the reaction conditions. One of the fatty acid salts was unsaturated, and it completely isomerized under the reaction conditions. One of the fatty acid salts was unsaturated, and a small percentage isomerized under the reaction conditions.

A triacylglycerol contains 3 carboxylic acids linked to glycerol. Treatment under basic conditions yielded 4 different fatty acids, so you know that one of the fatty acids must have reacted. A) Is incorrect. A triaylglycerol contains 3 fatty acid units. It was given that the triacylglycerol is pure so it cannot be two or more different kinds. B) is incorrect because glycerol treated under saponification conditions produces.... glycerol. Also if glycerol were to react, then all saponification reactions will have the product of glycerol reaction... which isn't true. C) is incorrect. If it completely isomerizes, then there would still be 3 different FAs. Besides it's super unlikely anything is completely isomerized D) Is consistent. Unsaturated fatty acids can undergo addition and elimination to produce cis/trans isomers under basic conditions. -- Consider A, B, C as the original connected to glycerol. You change all of C to D, now you have A, B, D which is still 3. Now if you isomerize some of C to D, now you have A, B, C, D.

Aldose vs. Ketose sugars

Aldose (aldehyde) Ketose (ketone)

What three polysaccharides are made of the same monosaccaride? How do they differ?

D-glucose makes cellular, starch and glycogen differ in glycosidic linkage location and anomeric carbon configuration

Tollen's reagent and Benedict's reagent

Reagents used to detect the presence of reducing sugars. Tollens - utilizes Ag(NH3)2+ as an oxidizing agent. If positive, aldehydes reduce the Ag+ to metallic silver Benedicts- the aldehyde group of an aldose is readily oxidized, which is indicated by a red precipitate of Cu2O

Tautomerism

The equation shows the migration of a hydrogen atom from an α-carbon atom to an oxygen atom. The hybridization of the α-carbonatom and oxygen atom change during the process. This is a description of tautomerism

what do you call a carb with six carbons with an aldehyde?

aldohexose

Mutarotation

The rapid interconversion between different anomers of a sugar, can happen when adding water to hemiacetal rings to spontaneously cycle between open and closed forms results in mix of both beta and alpha anomers at equilibrium concentrations (for glucose, its 36% alpha and 64% beta). The alpha is less favored bc of its axial position, adding steric hindrance to the molecule.

lactose is made of ___ and the glycosidic bonds are located at ___ and is (alpha or beta)

galactose and glucose, beta 1,4

lactone, example of one in every day life

When an aldose is oxidized (aldehyde group turns into carboxylic sugar), it makes a lactone. This is a cyclic ester with carbonyl group persisting as the anomeric carbon vitamin c

hemiacetals react with ___ to form acetals. the resulting CO bonds are called ___.

alcohol glycosidic bonds ie-glucose with EtOH

hemiacetal

aldehyde + alcohol

Glysosidic bond

aldehydes can participate in these, they are sugars acting as substituents

tetroses, pentoses, hexoses

carbohydrates w/ 4 carbons, 5, 6

Two sugars in the same family (like both are ketoses or aldoses, and same # electrons) that aren't identical and aren't mirror images are --

diastereomers

simplest ketone sugar is

dihydroxyacetone, a ketotriose

Epimers of glucose

epimers are subtypes of diastereomers that differ in configuration at ONE chiral center

Direction of rotation (+ or -) can be found by -

experimentally only, not by D or L only

sucrose is made of ___ and the glycosidic bonds are located at ___ and is (alpha or beta)

fructose and glucose at the 1,2, alpha

Two glucose molecules are combined to make an alpha 1,4 glycosidic bond, and this molecule is called

maltose

Monosaccharides have both a hydroxyl group that serves as a ____ and carbonyl group that serves as a ____.

nucleophile electrophile - most common

T/F: carbs are reduced to yield energy

oxidized

significance of phosphate esters in the human body

phosphate group on ATP is tranferred to glucose, phosphorylating it.

cellulose

plant cell walls, we cant digest bc we lack the enzyme cellulase, so its a great source of fiber since lots of water enters gut beta 1, 4 glycosidic bonds, chain of beta-D-glucose molecules

starches

plants store as amylose, more digestable since linked alpha D monomers.

The carbonyl carbon in a carb is the most _______ and will have the lowest possible number

the most oxidized and will also have the lowest possible

anomeric carbon

the new chiral center formed in ring closure; it was the carbon containing the carbonyl in the straight-chain form becomes alpha (-OH group trans to -CH2OH, axial and down) or beta (-OH group cis to -CH2OH, equatorial and down)

How do carbs undergo esterification?

they have hydroxyl groups that can react with carboxylic acids and its derivatives

most basic carb (monosaccharide) has ___ carbons and are called ___

three, trioses

homopolysaccharide vs heteropolysaccharide

• Homopolysaccharide - a polysaccharide that contains only one kind of monosaccharide • Heteropolysaccharide - a polysaccharide made of several monosaccharides