Lecture 8: Carbohydrate Flashcards
Carbohydrates (2)
What it is+used for
- Carbon-based molecules with many hydroxyl groups
- Used for energy storage, cellular recognition
Simple carbohydrate
Monosaccharides
Complex Carbohydrates
polysaccharides: polymers of covalently linked monosaccharides
Storage form of carbs
Glycogen
Carbs and its structural role
exoskeleton of insect (chitin), cell wall of plants, fungi and bacteria
carbohydrate formula+where they differ by
(CH2O)n
- where carbohydrates differ by the n and stereochemistry
Fisher projection (3)
- Open chain form of carbohydrate
- Horizontal bonds outwards
- Vertical bonds project backwards
Aldehyde
Keytone
Ketose
- 1 ketone group with two or more hydroxyl groups
Aldose
- 1 aldehyde group with two or more hydroxyl groups
D and L (4)
seen in+ the two+biological
- present in aldose
- D is OH group on right hand side
- L is OH group on left hand side
- Biological form is D
D or L is determined by
- the asymmetric carbon farthest from the aldehyde or ketone
- if the –OH group attached to the bottom-most asymmetric center (the carbon that is second from the bottom) is on the right, then, the compound is a D- sugar. If the –OH group is on the left, then, the compound is a L-sugar.
Constitutional isomers
Differ in the order of attachment of atoms
Stereoisomers
- The the same order of attachment of atoms but diff in spatial arrangement
Enantiomers
Non-super imposible mirror image
Example: D-sugars & L-sugars
Disatereomers (4)
What they are+ formula+different+ ex
- Isomer that are not mirror images
- same formula and connectivity
- Diastereomers have different physical properties (e.g., water solubility)
- epimers and anomers
Epimer (2)
type of +what is it
- type of diastereomer
- carbohydrates that differ in the location of the chiral centre of a -OH group in one location.
Anomers
Differ at a new asymmetric carbon atom formed on ring closure.
Ring closure: Why does it happen? (2)
- Aldehyde and alcohol group react with eachother
- Ketone and alcohol groups can react with eachother
Pyran
six membered ring
Furan
five membered ring
Anomeric Carbon
A carbon derived from the carbonyl carbon (the ketone or aldehyde functional group) of the open-chain form of the carbohydrate molecule.
alpha form in ring closure
OH attached to the anomeric carbo points down (Trans)
Beta form in ring closure
OH attached to the anomeric carbon points up (Cis)
Hemiacetal
a carbon with a single bond to OH and a single bond to OR (where R is a carbon group
an alcohol and ether attached to the same carbon
Chair vs Boat form
Chair form is favoured because there is less steric hindrance
Axial substituents and Equatorial
Axial substituents can sterically hinder eachother if they are on the same side of the ring. Equatorial substituents tend to be more spread out.
carbonyl carbon
a carbonyl group is a functional group with the formula C=O
The —- form predominates when fructose is free in solution
pyranose
The —- form predominates in many fructose derivatives
furanose
Monosaccharides (2)
what they are+ simplest?
- Aldehydes or ketones that have two or more hydroxl groups
- simplest monosaccarides are composed of 3 carbons:
