Lecture 8: Carbohydrate

Question 1

Carbohydrates (2)

What it is+used for

Answer 1

• Carbon-based molecules with many hydroxyl groups
• Used for energy storage, cellular recognition

Question 2

Simple carbohydrate

Answer 2

Monosaccharides

Question 3

Complex Carbohydrates

Answer 3

polysaccharides: polymers of covalently linked monosaccharides

Question 4

Storage form of carbs

Answer 4

Glycogen

Question 5

Carbs and its structural role

Answer 5

exoskeleton of insect (chitin), cell wall of plants, fungi and bacteria

Question 6

carbohydrate formula+where they differ by

Answer 6

(CH2O)n
- where carbohydrates differ by the n and stereochemistry

Question 7

Fisher projection (3)

Answer 7

• Open chain form of carbohydrate
• Horizontal bonds outwards
• Vertical bonds project backwards

Question 8

Aldehyde

Answer 8

Question 9

Keytone

Answer 9

Question 10

Ketose

Answer 10

• 1 ketone group with two or more hydroxyl groups

Question 11

Aldose

Answer 11

• 1 aldehyde group with two or more hydroxyl groups

Question 12

D and L (4)

seen in+ the two+biological

Answer 12

• present in aldose
• D is OH group on right hand side
• L is OH group on left hand side
• Biological form is D

Question 13

D or L is determined by

Answer 13

• 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.

Question 14

Constitutional isomers

Answer 14

Differ in the order of attachment of atoms

Question 15

Stereoisomers

Answer 15

• The the same order of attachment of atoms but diff in spatial arrangement

Question 16

Enantiomers

Answer 16

Non-super imposible mirror image

Example: D-sugars & L-sugars

Question 17

Disatereomers (4)

What they are+ formula+different+ ex

Answer 17

• Isomer that are not mirror images
• same formula and connectivity
• Diastereomers have different physical properties (e.g., water solubility)
• epimers and anomers

Question 18

Epimer (2)

type of +what is it

Answer 18

• type of diastereomer
• carbohydrates that differ in the location of the chiral centre of a -OH group in one location.

Question 19

Anomers

Answer 19

Differ at a new asymmetric carbon atom formed on ring closure.

Question 20

Ring closure: Why does it happen? (2)

Answer 20

• Aldehyde and alcohol group react with eachother
• Ketone and alcohol groups can react with eachother

Question 21

Pyran

Answer 21

six membered ring

Question 22

Furan

Answer 22

five membered ring

Question 23

Anomeric Carbon

Answer 23

A carbon derived from the carbonyl carbon (the ketone or aldehyde functional group) of the open-chain form of the carbohydrate molecule.

Question 24

alpha form in ring closure

Answer 24

OH attached to the anomeric carbo points down (Trans)

Question 25

Beta form in ring closure

Answer 25

OH attached to the anomeric carbon points up (Cis)

Question 26

Hemiacetal

Answer 26

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

Question 27

Chair vs Boat form

Answer 27

Chair form is favoured because there is less steric hindrance

Question 28

Axial substituents and Equatorial

Answer 28

Axial substituents can sterically hinder eachother if they are on the same side of the ring. Equatorial substituents tend to be more spread out.

Question 29

carbonyl carbon

Answer 29

a carbonyl group is a functional group with the formula C=O

Question 30

The —- form predominates when fructose is free in solution

Answer 30

pyranose

Question 31

The —- form predominates in many fructose derivatives

Answer 31

furanose

Question 32

Monosaccharides (2)

what they are+ simplest?

Answer 32

• Aldehydes or ketones that have two or more hydroxl groups
• simplest monosaccarides are composed of 3 carbons: