1. Carbohydrates

Question 1

what is a carbohydrate made up of and what is the ratio

Answer 1

contains: carbonyl (C=O) and hydroxyl groups
=aldehydes or ketones with 2 or more hydroxyl groups

ratio of C,H,O is 1:2:1

Question 2

can carbohydrates be 2C

Answer 2

no at least 3C etc

Question 3

major classes of carbohydrates (4)

Answer 3

1. monosaccharide (simple sugars)
   -single aldehyde or ketone with hydroxyl
2. disaccharide
   -2 units of monosaccharides
3. oligosaccharide
   -short chains (3-10) monosaccharides
4. polysaccharide
   -long chains/ more than 10 of monosaccharides

Question 4

oligosaccharides may be linked to other macromolecules such as _____ and_____

Answer 4

glycoproteins & glycolipids

Question 5

give 3 functions of carbohydrates

Answer 5

-store energy
-provide energy
-building blocks of macromolecules
-structural elements
-lipid metabolism

Question 6

how to name monosaccharides based on number of carbons

Answer 6

sugar molecule –> “ose” at end of name

n=3 triose
n=4 tetrose
n=5 pentose
n=6 hexose
n=7 heptose

Question 7

where do u start numbering carbons

Answer 7

end nearest the carbonyl group (C=O)

for ring: at carbonyl group

Question 8

aldose vs ketose based on carbonyl

Answer 8

aldose = carbonyl on end (aldehyde)
ketose = carbonyl inside (ketone)

Question 9

aldoses and ketoses are chiral?

Answer 9

YES - 4 different groups attached

Question 10

what are constitutional isomers

Answer 10

same composition, different connectivity

Question 11

how to get stereoisomers

Answer 11

2^power n

n=number of chiral centers

Question 12

enantiomers vs diastereomers

Answer 12

enantiomers = non superimposable MIRROR images (must have AT LEAST one chiral center)

diastereomers = NOT mirror images ex.cis/trans

Question 13

compare D and L enantiomers and how are they determined

Answer 13

D-sugars = OH group on the right
L-sugars = OH group on the left

-look at OH on whichever chiral carbon is farthest away from C=O

Question 14

what is the penultimate carbon

Answer 14

highest numbered chiral carbon

Question 15

where is carbon 1 drawn on a fischer projection

Answer 15

carbon #1 is always drawn ON TOP

Question 16

what does it mean to be reduced

Answer 16

gain H (usually breaks C=O to become OH)

Question 17

when could something no longer be distinguished as D or L sugars

Answer 17

if there is no longer a chiral carbon

Question 18

what are epimers

Answer 18

-two sugars that differ only in the configuration around ONE CARBON

Question 19

what are hemiacetals and hemiketals and what is special about their formations

Answer 19

hemiacetals = aldehydes attacked by alcohols
hemiketals = ketones attacked by alcohols

• new hemiacetal/hemiketal carbon becomes CHIRAL

Question 20

alpha-anomer vs Beta-anomer

Answer 20

alpha - OH opposite C6
beta - OH same as C6

Question 21

where is anomeric carbon

Answer 21

aldoses is C1
ketoses is C2

result of cyclization / on right side has OH / becomes chiral

Question 22

what is haworth projection and how to draw

Answer 22

cyclic ring structure

• to the right in fischer projection = are on bottom of ring

-below attacking group (usually OH) = goes on top of ring

Question 23

what is a furanose vs a pyranose

Answer 23

furanose = 5 membered ring
pyranose = 6 membered ring

Question 24

which membered ring is more stable

Answer 24

6 membered ring = pyranose

Question 25

what happens to pyranose at high temps

Answer 25

becomes furanose form ???

Question 26

what are configurational isomers and example

Answer 26

interconvert thru BREAKING and re-forming covalent bonds

ex.alpha or beta

Question 27

what are conformational isomers and example

Answer 27

interconvert WITHOUT BREAKING of covalent bonds

ex. endo or exo

Question 28

what is meant by endo / exo

Answer 28

endo = same face (ex. both dash lines)
- C2 is on same side as C5

exo = opposite faces (one dash one solid line)
-C2 is on opposite side as C5

Question 29

what is dehydration synthesis

Answer 29

monosaccharides linked by O-glycosidic bond and has removal of water

Question 30

describe formation of glycosidic bond

Answer 30

AT LEAST ONE anomeric carbon is used for bond formation

Question 31

what does it mean to be a reducing sugar

Answer 31

has a free anomeric carbon

Question 32

are all monosaccharides and disaccharides reducing sugars?

Answer 32

monosaccharides - YES
disaccharides - NO only if have free anomeric carbon

Question 33

how to name if reducing or non reducing

Answer 33

reducing - “ose”
nonreducing - “oside”

Question 34

when to add “syl” to end of name of first molecule

Answer 34

if anomeric carbon is involved in glycosidic bond

Question 35

could oligosaccharides have 1->1 linkages

Answer 35

no cuz has 3-10 monosaccharides linked and if had 1->1 then would not have a free anomeric carbon for 3rd to link to

Question 36

homo vs heteropolysaccharide

Answer 36

homo - only one type of monosaccharide
hetero - more than one type of monosaccharide

Question 37

what is the function of alpha glycosidic bonds

Answer 37

energy storage

Question 38

what is the function of beta glycosidic bonds

Answer 38

structure

Question 39

what are glucan homopolymers

Answer 39

contain only alpha-D-glucopyranose

starch
glycogen
cellulose

Question 40

describe starch

Answer 40

energy storage for plants

amylose - linear (a1->4)
amylopectin - (a1->4 linkages and a1->6 branched linkages )

Question 41

describe glycogen

Answer 41

energy storage in animals

(a1->4 linkages and a1->6 branched linkages )

Question 42

describe cellulose

Answer 42

structural component of cell wall

BETA1->4 glycosidic bonds !
-linear
-each monomer is turned 180 relative to neighbor

Question 43

describe chitin

Answer 43

BETA 1->4 linkages
-homopolysaccharide
-found in exoskeleton

Question 44

what is most stable conformation of cellulose

Answer 44

straight extended chain

*hydrogen bonds between chains to promote sheets