ch 23: carbohydrates and nucleic acids

Question 1

carbohydrate

Answer 1

has many hydroxyl groups attached
- polyhydroxy aldehyde or ketone

Question 2

monosaccharide

Answer 2

simple sugars that are aldoses or ketoses

Question 3

aldose

Answer 3

polyhydroxyaldehydes

Question 4

ketose

Answer 4

polyhydroxyketones

Question 5

disaccharides

Answer 5

hydrolyzed to two monosaccharides

Question 6

polysaccharides

Answer 6

hydrolyze to many monosaccharide units

Question 7

how are monosachharides classified?

Answer 7

1. present of either ketone or aldehyde group
2. number of carbons in the chain
3. configuration of the asymmetric carbon farther from carbonyl group

Question 8

why does the asymmetric carbon farthest away from the carbonyl matter?

Answer 8

because all monosaccharides can be chemically degraded to glyceraldehyde but only the dextrorotatory or + enantimer of glyceraldehyde is encountered in nature
- so all naturally occurring monosaccharides can be degraded to + glyceraldehyde and classified as D-sugars

Question 9

KNOW GLYCERALDEHYDE STRUCTURE

Question 10

structure of D series sugars

Answer 10

have OH group of the bottom asymmetric carbon on the RIGHT

Question 11

structure of L series sugars

Answer 11

have OH group of the bottom asymmetric carbon on the LEFT

Question 12

what is the most important monosaccharide?

Answer 12

glucose - D sugar
- aldohexose

Question 13

what are the pyranose (cyclic forms) of glucose known as?

Answer 13

equilibrium mixtures of anomers

Question 14

what does cyclization create?

Answer 14

a new stereocenter that has 2 cyclic forms: a-anomer and b-anomer

Question 15

what is the interconversion of a-anomer and b-anomer called?

Answer 15

mutarotation

Question 16

what is the formation of pyranose rings enabled by?

Answer 16

cyclic hemi-acetals

Question 17

what is the site of reactivity in carbs?

Answer 17

anomeric carbon

Question 18

fructose

Answer 18

ketohexose that exists as a 5-membered acetal

Question 19

what does the a-anomer of fructose have?

Answer 19

anomeric OH group down, trans to the terminal CH2OH group

Question 20

what does the b anomer of fructose have?

Answer 20

anomeric OH group cis to the terminal CH2OH

Question 21

what is the reactivity of the anomeric carbon used for?

Answer 21

to connect two monsacchardies to form disaccharides

Question 22

1-4 glycosodic linkage

Answer 22

the anomeric carbon is bonded to oxygen on C4 of second sugar

Question 23

1-6 glycosodic linkage

Answer 23

the anomeric carbon is bonded to oxygen on C6 of second sugar

Question 24

1-1 glycosodic linkage

Answer 24

the anomeric carbons of the two sugars are bonded through an oxygen

Question 25

how many bonds does a dissacharide have to have?

Answer 25

at least one

Question 26

what does a b- 1-4 glycosidic bond linking 2 glucose molecules give?

Answer 26

a disaccharide called cellubiose: degradation product of cellulose