L.12 Carbohydrates

Question 1

How are carbohydrates organized?

Answer 1

by their number of carbons and functional groups

Question 2

Three common names for carbohydrates

Answer 2

• Glucose
• Fructose
• Galactose

Question 3

What are 3 carbon sugars? Four?

Answer 3

Trioses

Tetroses

Question 4

Sugars with Aldehydes and Sugars with

Ketones as their most oxidized group are named what?

Answer 4

Aldoses

Ketoses

Question 5

Nomenclature of sugars

Answer 5

Nomemclature of all sugar is based on the

D- and L- forms of glyceraldehyde.

Sugars with the highest-numbered chiral carbon with the -OH group on the RIGHT (fisher projection) are D sugars/

on left, L Sugars.

D & L = Enantiomeres

Glyceraldehyde is a triose monosaccharide with chemical formula C3H6O3. It is the simplest of all common aldoses. It is a sweet, colourless crystalline solid that is an intermediate compound in carbohydrate metabolism.

Question 6

What are diastereomers

Answer 6

Non-superimposable configurations of molecules with similar connectivity. They differ at at least one - but - not all chiral carbons. These include

Epimers; differ at one chiral carbon

Anomers; differ at the anomeric carbon

Question 7

Cyclization describes the ring formation of carbohydrates, when these form, the anomeric carbon can take either an alpha or beta conformation.

The anomeric carbon is the new chiral center formed in the ring closure,

it was the carbon containing the carbonyl.

Alpha-anomers have the -OH on the anomeric

carbon ______ to the free -CH₂OH group.

;

beta- anomers?

Answer 7

Alpha TRANS

Beta CIS

Question 8

Hawthorn Projections provide?

Answer 8

Provide a good way to represent 3D structures

Question 9

Cyclic compounds can undergo MUTAROTATION, which is what?

Answer 9

Shifting from one anomeric for to another with the straight chain form as an intermediate.

Question 10

What are Monosaccharides?

What 3 main reactions can they undergo?

Answer 10

single carbohydrate units, with glucose as the most commonly observed monomer.

They can undergo 3 main reactions.

1. oxidation-reduction
2. esterification
3. glycoside formation

Question 11

Aldoses can be oxidized and reduced to produce what?

Answer 11

Oxidized; Aldonic Acids

Reduced; Alditols

Question 12

What kind of sugars can be reacted with Tollen’ or Benedict’s reagents to detect those sugars?

Answer 12

Sugars that can oxidized are reducing agents (reducing sugars)

Question 13

Sugars with an -H replacing an -OH are termed?

Answer 13

DEOXY Sugars

Question 14

Sugars that react with carboxylic acids and their derivatives form what?

Answer 14

ESTERS in an esterification reaction

Question 15

What is phosphorylation?

Answer 15

Phosphate ester is formed by transfering a phospahete group from ATP onto a sugar

Question 16

Glycoside formation

Answer 16

is the basis for building complex carbohydrates and requires the anomeric carbon to link to another sugar

Question 17

What are dissacharides?

Answer 17

form as a result of glycosidic bonding berween two monosacharide subunits;

polyssacharides form by reapeated monossacharide or polyssacharide glycosidic bonding

Question 18

What are the 3 common disaccharides?

Answer 18

1. Sucrose glucose-alpha-1,2-fructose

2. Lactose galactose-beta-1,4-glucose

3. Maltose glucose-alpha-1,4-glucose

Question 19

What 3 main roles do polysaccharides play?

Answer 19

As

Cellulose;

the main source of fiber in the human diet found in plants cell walls for a structural component

Starches (amylose and amylopectin);

main energy storage form for plants

Glycogen;

main energy storage form for animals