Carbohydrate structure and reactions

Question 1

What are 10 functions of carbohydrates?

Answer 1

Energy storage
Energy source
Structure 
Components of nucleotides
Protection 
Lubrication
Communication
Information storage 
Mediation of cell adhesion and signalling 
Protein localization and activity

Question 2

What is the general formula of a carbohydrate? What is n?

Answer 2

(CH2O)n. n is between 3 and 7

Question 3

What functional group does every carbon in a sugar have?

Answer 3

Either a carbonyl or a hydroxyl

Question 4

What is an aldehyde sugar called?

Answer 4

Aldose

Question 5

What is a ketone sugar called?

Answer 5

Ketose

Question 6

What are the 3 class sizes of sugars?

Answer 6

Monosaccharides, oligosaccharides, polysaccharides

Question 7

What type of bond links sugars together?

Answer 7

Glycosidic bonds

Question 8

Are monosaccharides water soluble?

Answer 8

Yes, usually

Question 9

Are oligosaccharides water soluble?

Answer 9

Yes, usually

Question 10

Are polysaccharides water soluble?

Answer 10

Not usually

Question 11

What is a homopolysaccharide?

Answer 11

Polymer of only one sugar type

Question 12

What is a heteropolysaccharide?

Answer 12

Polymer of multiple types of sugars

Question 13

What are glyconjugates?

Answer 13

Sugars that are attached to other stuff, namely lipids and proteins

Question 14

What is the most common number of carbons in a monosaccharide?

Answer 14

6

Question 15

What is the smallest chiral sugar?

Answer 15

Glyceraldehyde

Question 16

What carbon does numbering start at in a sugar ring?

Answer 16

The one closest to the carbonyl

Question 17

How big do sugars need to be to cyclize in solution?

Answer 17

At least 4 carbons

Question 18

How many stereoisomers are there with multiple chiral centres?

Answer 18

For n chiral centres, there’s 2^n stereoisomers

Question 19

What determines if a sugar is D or L?

Answer 19

The configuration at the carbon farthest from the carbonyl compared to glyceraldehyde. The D isomer has the hydroxyl on that carbon pointing right

Question 20

Are most naturally occurring sugars L or D?

Answer 20

D

Question 21

What are epimers?

Answer 21

Sugars that differ in stereochemistry only at 1 carbon atom

Question 22

What are enantiomers?

Answer 22

Molecules that are non-superimposable mirror images of each other

Question 23

What are diastereomers?

Answer 23

Stereoisomers that aren’t mirror images

Question 24

What happens to linear monosaccharides in solution?

Answer 24

They are susceptible to nucleophilic attack by alcohols to form hemiacetals or hemiketals

Question 25

The hydroxyl on which carbon will attack the carbonyl in a hexose sugar?

Answer 25

Carbon 5

Question 26

What happens to the carbonyl carbon when nucleophilic attack happens?

Answer 26

Becomes a hydroxyl that can point either up or down depending on the direction of attack

Question 27

What type of linkage is formed when intramolecular cyclization occurs in a sugar?

Answer 27

Ether

Question 28

What is the anomeric carbon?

Answer 28

The carbon that formerly had the carbonyl

Question 29

What is the alpha anomer of a hexose sugar?

Answer 29

Carbon 6 and the OH on the anomeric carbon are on different sides

Question 30

What is the stereochemistry of an alpha anomeric carbon if there is no carbon 6 hanging off the ring?

Answer 30

S

Question 31

What is the beta anomer of a hexose sugar?

Answer 31

Both carbon 6 and the OH on the anomeric carbon are on the same side of the ring

Question 32

What is the stereochemistry of a beta anomeric carbon if there is no carbon 6 hanging off the ring?

Answer 32

R

Question 33

Is alpha or beta glucose more stable?

Answer 33

Beta

Question 34

Why is beta glucose more stable than alpha glucose?

Answer 34

Has all the hydroxyls in equatorial positions

Question 35

What is a 6 membered ring called?

Answer 35

Pyranose

Question 36

What is a 5 membered ring called?

Answer 36

Furanose

Question 37

What are 5 modifications of hexoses that can be made by substituting out a hydroxyl?

Answer 37

``` Oxidize to COOH Phosphorylation Deoxy sugars Amides Sialic acid ```

Question 38

What is a reducing sugar?

Answer 38

A sugar that can reduce Cu2+

Question 39

Are aldehydes able to be oxidized?

Answer 39

Yes, into COOH

Question 40

Are ketones able to be oxidized?

Answer 40

No

Question 41

Are aldoses or ketoses reducing sugars?

Answer 41

Aldoses

Question 42

Is glucose a reducing sugar?

Answer 42

Yes

Question 43

How does glucose testing for diabetes work?

Answer 43

Uses glucose oxidase and peroxidase to produce a coloured precipitate

Question 44

What is hemoglobin glycation?

Answer 44

Non-enzymatic reaction between glucose and Hb, with glucose reacting with NH2 groups in Hb. More glucose in the blood means more glycated Hb

Question 45

What happens to glycated hemoglobin?

Answer 45

Glycation causes rearrangements, oxidations, and dehydrations of hemoglobin, which makes it unusually reactive

Question 46

What does a monosaccharide in solution become when it forms a glycosidic bond?

Answer 46

An acetal or ketal

Question 47

What is a glycosidic bond?

Answer 47

A bond between any of the OH groups on one sugar and the anomeric carbon on the other sugar

Question 48

What is an O glycoside?

Answer 48

The atom in the glycosidic bond is an O

Question 49

What is an N glycoside? Where is this found?

Answer 49

The atom in the glycosidic bond is an N. Found in nucleotides and in sugars attached to asparagine

Question 50

How do you name sugars?

Answer 50

Have the non-reducing end on the left, then figure out if the anomeric carbon is alpha or beta. Name the monosaccharide with the non-reducing end. Then identify the carbons in the glycosidic bond. Name the second monosaccharide. Continue for a longer chain