Chapter 11 Notes

Question 1

CHOs with ketones?

Answer 1

ketoses

Question 2

CHOs with aldehydes?

Answer 2

aldoses

Question 3

What are the most common 6-carbon CHOs?

Answer 3

allose, altrose, glucose, mannose, gulose, idose, galactose, talose

Question 4

Which 6-carbon CHOs are considered epimers of each other?

Answer 4

glucose, mannose, galactose

Question 5

Mannose and galactose are __.

Answer 5

disterioisomer

Question 6

When dissolved in water, hexoses assume ring structures and form structures referred to as __ and ___.

Answer 6

hemiacetals, hemiketals

Question 7

Mutarotation?

Answer 7

when the anomeric carbon atom can exist in equilibrium between 2 stereochemial states: alpha or beta (anomers)

Question 8

What are the most reactive compound groups of CHOs?

Answer 8

anomeric carbon and hydroxyl group

Question 9

what is unique about fructose?

Answer 9

can form both 5- and 6- membered rings where each forms a new chiral center

Question 10

Why is the chair structure more favored?

Answer 10

due to less steric hindrance - beta form preferred at 66%

Question 11

Monosaccharides may react with alchols and amines to form modified monosaccharides via __ bonding.

Answer 11

glycosidic

Question 12

Difference between O and N glycosidic bonds?

Answer 12

O-oxygen attached

N-Nitrogen attached

Question 13

Why are aldoses referred to as reducing sugars?

Answer 13

they can undergo oxidation-reduction reactions that reduce metals such as Ca or Ag

Question 14

Fehling’s reagent?

Answer 14

Cu2+ (oxidized form)

Question 15

In the presence of reducing sugars, Fehlings reagent becomes reduced to __.

Answer 15

Cu+ which reacts with oxygen and forms a red precipitate

Question 16

Where does modification occur?

Answer 16

only at the anomeric hydroxyl group because it is the only one that can open up

Question 17

How can CHO be modified?

Answer 17

by addition of various substituents to yield biologically important molecules

Question 18

Where does reduction occur?

Answer 18

at functional group

Question 19

__ bonds often form between monosaccharides to produce disaccharides and larger polysaccharides.

Answer 19

glycosidic bonds

Question 20

Once a __ bond is formed, the reducing properties of the sugar are lost.

Answer 20

glycosidic

Question 21

polysaccharides?

Answer 21

large polymeric oligosaccharides formed by linkage of multiple monosaccharides called polysaccharides; play an important role in energy storage: starch (amylopectin and amylose) and glycogen

Question 22

What makes cellulose, starch, and glycogen so strong?

Answer 22

the many nonreducing ends in glycogen allow for rapid metabolism and release and add glucose molecules (enzymes attack nonreducing ends to mobilize glycogen more easily - due to branching); unbranched beta1,4 linkages between glucose allows maximum hydrogen bonding and stacking of linear chains - the resulting structure is fibril-like with high tensile strength due to thier repeating hydrogen bonding patterns

Question 23

CHOs can be attached to proteins to form __.

Answer 23

glycoproteins

Question 24

When N-glycosidic bond = forms __.

Answer 24

asparagine

Question 25

when O-glycosidic bond = forms __.

Answer 25

serine

Question 26

Which AA combination allows for the sugar to form for N-glycosidic bond?

Answer 26

Asn-X-Ser or Asn-X-Thr

Question 27

What is the specific AA sequence for sugar to form for O-glycosidic bond?

Answer 27

no particular sequence - just attaches freely