Lecture 1

Question 1

true or false; glucose is a monosaccharide

Answer 1

true

Question 2

where is the -OH group attached to glucose carbon #? left or right hand side?

Answer 2

5; right

Question 3

What does it mean by reducing power?

Answer 3

’ free aldehyde group contained on an aldose sugar which is relatively easy to oxidize to a carboxylic acid group’

Question 4

Why is the reducing power of glucose less than expected?

Answer 4

glucose straight chain form is in equilibrium with its cyclic form

Question 5

true or false; equilibrium heavily favors these cyclic forms

Answer 5

true

Question 6

What are the most abundant type of ologosaccharides?

Answer 6

disaccharides

Question 7

why doesn’t ologosaccharides exist in equilibrium forms

Answer 7

one of the sugars is fixed in either alpha or beta form

Question 8

What do the polysaccharide chains differ in?

Answer 8

• identity of reccuring monosaccharide units
• length of their chains
• types of bonds linking the units
• degree of branching of the chains

Question 9

glucose + glucose =

Answer 9

maltose

Question 10

glucose + galactose =

Answer 10

lactose

Question 11

glucose + fructose =

Answer 11

sucrose

Question 12

What are the most abundant polysaccharides?

Answer 12

starch and cellulose

Question 13

Describe cellulose structure

Answer 13

B 1-4 linkages
insoluble
structural polysaccharides
parallel bundles

Question 14

what is the most common form of carbohydrate occurring in nature (D or L)

Answer 14

D form

Question 15

Describe starch

Answer 15

storage polysaccharides
linkages of monomers ( a 1-4 or a 1-4 and a 1-6)
two forms: amylose and amylopectin
natural curvature (due to linkages)
- OH groups point outwards
(enables starch to be soluble in water; as OH can form hydrogen bonds with water)

Question 16

Why is solubility important for starch?

Answer 16

so that it will be able to be hydrolyzed by enzymes to yield glucose

Question 17

Describe amylopectin

Answer 17

a 1-6 branch points

Question 18

Describe glycogen

Answer 18

principal of storage form of sugars for higher animals
glucose monomers linked ( a 1-4 and a 1-6)
more highly branched than amylopectin
soluble

Question 19

Describe chitin

Answer 19

structural polysaccharide
found in exoskeletons of anthropods
similar to cellulose (but contains nitrogen appendage on each glucose)
linkage beta 1-4

Question 20

define epimer

Answer 20

type of diastereomer that differs only in configuration at 1 chirality center

Question 21

Define anomer

Answer 21

differ in orientations of one group (open chain forms exist in equilibrium with closed ring forms)

Question 22

Define enantiomer

Answer 22

have opposite configuration at all chirality centers (mirror images )

Question 23

Define diastereomer

Answer 23

oppposite configuration at some chiral centers; but same configuration in others

Question 24

Define stereoisomer

Answer 24

same molecular formula; differ in 3D organisation of atoms in space

Question 25

Define chirality

Answer 25

• non super imposable

- 4 different groups attached to central atom

Question 26

rule of stereoisomers

Answer 26

2n (n are # of chirality centers)

Question 27

Describe amylose

Answer 27

has only alpha 1-4 linkages
helix shape
no alpha 1-6