Carbohydrates

Question 1

What is the most abundant biomolecule?

Answer 1

carbs

Question 2

What are carbs used for? (4 answers)

Answer 2

• cell walls
• lubricating skeletal joints
• cell recognition
• adhesion

Question 3

What do “glycoconjugates” do?

Answer 3

provide “labels” for cellular destinations

Question 4

What is the general formula for carbs?

Answer 4

Cn(H20)n

Question 5

What is an “aldose”?

Answer 5

carbonyl carbon (C=O) is 1st in chain

Question 6

What is an “ketose”?

Answer 6

carbonyl carbon in 2nd position

Question 7

What is the general formula for a monosaccharide?

Answer 7

(C-H2O)n

Question 8

What are monosaccharides?

Answer 8

aldehydes or ketones containing 2 or more hydroxyl groups

Question 9

What 2 smallest monosaccharides are isomers?

Answer 9

• glyceraldehyde

- dihydroxyacetone

Question 10

Draw D-glucose

Answer 10

CH20HCH(OH)CH(OH)CH(OH)CH(OH)CHO

Question 11

Draw D-mannose

Answer 11

CH20HCH(OH)CH(OH)CH(OH)CH(OH)CHO

Question 12

Draw D-galactose

Answer 12

CH20HCH(OH)CH(OH)CH(OH)CH(OH)CHO

Question 13

Draw D-fructose

Answer 13

CH20HCH(OH)CH(OH)CH(OH)C=OCH2OH

Question 14

What is “stereochemistry”?

Answer 14

study of arrangement of atoms in 3D space

Question 15

What is a “stereoisomer”?

Answer 15

molecules that have the same bonds connecting the same atoms but different orientations of bonds

Question 16

What is “chirality”?

Answer 16

asymmetric molecules

Question 17

What sugar is present in humans L or D?

Answer 17

D

Question 18

What form are amino acids in, L or D for human usage?

Answer 18

L

Question 19

What is an “epimer”?

Answer 19

differ only in configuration around one or many chiral carbons

Question 20

What is an example of an epimer?

Answer 20

D-glucose and D-mannose

Question 21

What is an “enantiomer”?

Answer 21

a chiral compound and its mirror image

Question 22

What is an “optical isomer” an example of?

Answer 22

stereoisomer

Question 23

What does “D” stand for in isomers?

Answer 23

dexter (right)

Question 24

What does “L” stand for in isomers?

Answer 24

laevus (left)

Question 25

What gives carbs diversity and specificity?

Answer 25

multiple chiral carbons present

Question 26

What are chiral carbons presented as?

Answer 26

Fischer projections

Question 27

In Fischer projections, where are the horizontal bonds pointing?

Answer 27

towards you

Question 28

In Fischer projections, where are the vertical bonds pointing?

Answer 28

away from you

Question 29

What is the "stereochemical configuration" of a sugar?

Answer 29

chiral carbon at the greatest distance from the carbonyl carbon

Question 30

To form a cyclic sugar, a reaction between 2 chemical groups occur to form a hemiacetal, what react together?

Answer 30

aldehyde and alcohol

Question 31

To form a cyclic sugar, a reaction between 2 chemical groups occur to form a hemiketal, what react together?

Answer 31

ketone and alcohol

Question 32

When -OH at C1 is below the plane of the ring, what is the molecule called?

Answer 32

alpha-anomer

Question 33

When -OH at C1 is above the plane of the ring, what is the molecule called?

Answer 33

beta-anomer

Question 34

What does a "Haworth projection" show?

Answer 34

3D representation of cyclic carbs

Question 35

What ring structure are hexose sugars derived from?

Answer 35

pyran

Question 36

What ring structure are pentose sugars derived from?

Answer 36

furan

Question 37

What does "-ose" indicate?

Answer 37

multiple hydroxyls

Question 38

How is cyclic glucose produced?

Answer 38

C-5 OH attacks C-1 aldehyde group (CHO)

Question 39

What is formed when glucose is cyclised?

Answer 39

intramolecular hemiacetal

Question 40

How is cyclic fructose produced?

Answer 40

C-5 OH attacks C-2 ketone group (COH)

Question 41

What is formed when fructose is cyclised?

Answer 41

intramolecular hemiketal

Question 42

What is "fructose"?

Answer 42

a 5 membered furanose ring or 6 membered pyranose ring

Question 43

What is "fructose" used in?

Answer 43

sweeteners

Question 44

What causes "chair" and "boat" conformations?

Answer 44

steric hindrance

Question 45

What are the 2 tests for aldehydes?

Answer 45

- Fehling's/Benedict's Test | - Tollens' Test

Question 46

What are the observations in Fehling's/Benedict's Test?

Answer 46

blue to red colour change (Positive) as Cu2+ is reduced to Cu+

Question 47

What sugar is not reduced during Benedict's Test?

Answer 47

Sucrose

Question 48

What are the observations in Tollens' Test?

Answer 48

Silver Mirror formation as Ag+ is reduced to AgO

Question 49

Why are sugars phosphorylated?

Answer 49

makes sugars anionic (negative) prevents them from leaving cell

Question 50

What are 2 examples of modified carbs?

Answer 50

- glycoprotein | - glycolipid

Question 51

What is an "O-glycosidic bond"?

Answer 51

anomeric carbon atom and oxygen atom of an alcohol

Question 52

What is an "N-glycosidic bond"?

Answer 52

anomeric carbon atom and amine

Question 53

When a disaccharide is produced, what groups are formed? (2 answers)

Answer 53

- two acetal groups | - one hemiacetal

Question 54

What are the monosaccharides of maltose?

Answer 54

glucose and glucose

Question 55

What are the monosaccharides of sucrose?

Answer 55

glucose and fructose

Question 56

What are the monosaccharides of lactose?

Answer 56

glucose and galactose

Question 57

When an anomeric C atom and an O atom form a bond, what is the product called?

Answer 57

glycoside