Carbohydrate structure and reactions Flashcards

1
Q

What are 10 functions of carbohydrates?

A
Energy storage
Energy source
Structure 
Components of nucleotides
Protection 
Lubrication
Communication
Information storage 
Mediation of cell adhesion and signalling 
Protein localization and activity
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2
Q

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

A

(CH2O)n. n is between 3 and 7

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3
Q

What functional group does every carbon in a sugar have?

A

Either a carbonyl or a hydroxyl

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4
Q

What is an aldehyde sugar called?

A

Aldose

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5
Q

What is a ketone sugar called?

A

Ketose

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6
Q

What are the 3 class sizes of sugars?

A

Monosaccharides, oligosaccharides, polysaccharides

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7
Q

What type of bond links sugars together?

A

Glycosidic bonds

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8
Q

Are monosaccharides water soluble?

A

Yes, usually

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9
Q

Are oligosaccharides water soluble?

A

Yes, usually

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10
Q

Are polysaccharides water soluble?

A

Not usually

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11
Q

What is a homopolysaccharide?

A

Polymer of only one sugar type

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12
Q

What is a heteropolysaccharide?

A

Polymer of multiple types of sugars

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13
Q

What are glyconjugates?

A

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

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14
Q

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

A

6

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15
Q

What is the smallest chiral sugar?

A

Glyceraldehyde

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16
Q

What carbon does numbering start at in a sugar ring?

A

The one closest to the carbonyl

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17
Q

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

A

At least 4 carbons

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18
Q

How many stereoisomers are there with multiple chiral centres?

A

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

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19
Q

What determines if a sugar is D or L?

A

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

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20
Q

Are most naturally occurring sugars L or D?

A

D

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21
Q

What are epimers?

A

Sugars that differ in stereochemistry only at 1 carbon atom

22
Q

What are enantiomers?

A

Molecules that are non-superimposable mirror images of each other

23
Q

What are diastereomers?

A

Stereoisomers that aren’t mirror images

24
Q

What happens to linear monosaccharides in solution?

A

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

25
The hydroxyl on which carbon will attack the carbonyl in a hexose sugar?
Carbon 5
26
What happens to the carbonyl carbon when nucleophilic attack happens?
Becomes a hydroxyl that can point either up or down depending on the direction of attack
27
What type of linkage is formed when intramolecular cyclization occurs in a sugar?
Ether
28
What is the anomeric carbon?
The carbon that formerly had the carbonyl
29
What is the alpha anomer of a hexose sugar?
Carbon 6 and the OH on the anomeric carbon are on different sides
30
What is the stereochemistry of an alpha anomeric carbon if there is no carbon 6 hanging off the ring?
S
31
What is the beta anomer of a hexose sugar?
Both carbon 6 and the OH on the anomeric carbon are on the same side of the ring
32
What is the stereochemistry of a beta anomeric carbon if there is no carbon 6 hanging off the ring?
R
33
Is alpha or beta glucose more stable?
Beta
34
Why is beta glucose more stable than alpha glucose?
Has all the hydroxyls in equatorial positions
35
What is a 6 membered ring called?
Pyranose
36
What is a 5 membered ring called?
Furanose
37
What are 5 modifications of hexoses that can be made by substituting out a hydroxyl?
``` Oxidize to COOH Phosphorylation Deoxy sugars Amides Sialic acid ```
38
What is a reducing sugar?
A sugar that can reduce Cu2+
39
Are aldehydes able to be oxidized?
Yes, into COOH
40
Are ketones able to be oxidized?
No
41
Are aldoses or ketoses reducing sugars?
Aldoses
42
Is glucose a reducing sugar?
Yes
43
How does glucose testing for diabetes work?
Uses glucose oxidase and peroxidase to produce a coloured precipitate
44
What is hemoglobin glycation?
Non-enzymatic reaction between glucose and Hb, with glucose reacting with NH2 groups in Hb. More glucose in the blood means more glycated Hb
45
What happens to glycated hemoglobin?
Glycation causes rearrangements, oxidations, and dehydrations of hemoglobin, which makes it unusually reactive
46
What does a monosaccharide in solution become when it forms a glycosidic bond?
An acetal or ketal
47
What is a glycosidic bond?
A bond between any of the OH groups on one sugar and the anomeric carbon on the other sugar
48
What is an O glycoside?
The atom in the glycosidic bond is an O
49
What is an N glycoside? Where is this found?
The atom in the glycosidic bond is an N. Found in nucleotides and in sugars attached to asparagine
50
How do you name sugars?
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