Second Half I F24: Lecture Slides 58 - 74

Question 1

What D-Sugars what are OH groups?

Answer 1

Left in Fischer Formula and Above in Haworth

Question 2

Where is the Anomeric OH in Beta form?

Answer 2

Above Ring

Question 3

Where is the Anomeric OH in Alpha Form?

Answer 3

Below Ring

Question 4

How do you remember where the anomeric carbon is located?

Answer 4

LAB: Left —-> Above <—- Beta

Question 5

What is the Carbonyl Carbon?

Answer 5

Always the electrophile in the reaction (will form the anomeric carbon)

Question 6

What can any of the OH groups act as?

Answer 6

The nucleophile

Question 7

What does which OH reacting with the Carbonyl C depend on?

Answer 7

The type of ring that is formed (pyranose or furanose)

Question 8

What happens if the OH of carbon 6 is the nucleophile?

Answer 8

Fructose will form a 6-membered pyranose ring.

Question 9

What is the anomeric carbon of a sugar?

Answer 9

An electrophile

Question 10

What does the anomeric carbon being an electrophile make the sugar?

Answer 10

Reactive; at this positions most reactions involving ring forms of sugars take place.

Question 11

What is the most important reaction of sugars?

Answer 11

The condensation of the anomeric carbon with the nucleophilic -OH of an alcohol or the -NH of an amine

Question 12

What is the resulting molecule called?

Answer 12

A glycoside

Question 13

What is the bond formed known as?

Answer 13

Glycosidic (C - O) or A glycosidic (C - N) bond

Question 14

What happens if the anomeric carbon is associated in a glycosidic bond?

Answer 14

The sugar (in the ring form) can no longer open up to assume the linear form

Question 15

What type of chains are able to undergo oxidation?

Answer 15

Open chain forms

Question 16

What happens when the sugar can no longer open up to assume the linear form?

Answer 16

The sugar residue becomes a non-reducing sugar

Question 17

What is a reducing sugar?

Answer 17

A free hydroxyl that is only found in linear form.

Question 18

How are disaccharides formed?

Answer 18

When two monosaccharides are linked through a glycosidic bond.

Question 19

How does a disaccharide reaction occur?

Answer 19

When the anomeric carbon (electrophile) of one sugar reacts with the hydroxyl group (nucleophile) of the other

Question 20

What are Disaccharides?

Answer 20

Glycosides

Question 21

How is Lactose formed?

Answer 21

The condensation of glucose with Galactose

Question 22

What is Lactose named?

Answer 22

gal(B1 ->4)glc

Question 23

How is the glycosidic bond of lactose formed?

Answer 23

The glycosidic bond is described as (B1 -> 4): going from C-1 of galactose in the B configuration to C-4 of glucose

Question 24

Why can’t the anomeric carbon of galactose unable to undergo mutarotation?

Answer 24

It is involved in a glycosidic bond, therefore unable to form the linear form

Question 25

What does the anomeric carbon in galactose become?

Answer 25

Non-reducing

Question 26

What is the Anomeric Carbon in Glucose?

Answer 26

Free, therefore able to undergo mutarotation existing in either a(a-lactose), B(B-lactose) or linear forms

Question 27

What is Lactose able to act as?

Answer 27

A reducing sugar

Question 28

In disaccharides and polysaccharides, what is the end of a chain with a free anomeric carbon called?

Answer 28

Reducing End

Question 29

What must the formation of the glycosidic bond of a disaccharide must involve?

Answer 29

The anaemic carbon of one sugar, because that is the only electrophilic C atom in a sugar.

Question 30

What could galactose and glucose form?

Answer 30

Lots of different disaccharides besides lactose, making structural isomers of lactose.

Question 31

What are the anomeric carbons of Glucose and Fructose involved in?

Answer 31

The glycosidic bond

Question 32

What does both anaemic carbons being involved in the glycosidic bond mean?

Answer 32

Surcose is a non-reducing sugar.

Question 33

What does Glucose and Fructose produce?

Answer 33

Sucrose

Question 34

What is the Name of Maltose?

Answer 34

glc(a1-4)glc

Question 35

What is Maltose?

Answer 35

Formed by the breakdown of starch

Question 36

What is Trehalose?

Answer 36

glc(a1-a1)glc *A non-reducing sugar

Question 37

What are most carbohydrates?

Answer 37

Highly branched.

Question 38

How is branching possible?

Answer 38

As sugars have several OH groups, each of which can act as the nucleophile in forming a glycosidic bond, bonding a single subunit to two (or more) others.

Question 39

What are Homopolysacchardies?

Answer 39

Made from a single type of sugar monomer

Question 40

What are heteropolysacchardies?

Answer 40

Made from two or more kinds of sugar monomers