Lecture 1 Flashcards
true or false; glucose is a monosaccharide
true
where is the -OH group attached to glucose carbon #? left or right hand side?
5; right
What does it mean by reducing power?
’ free aldehyde group contained on an aldose sugar which is relatively easy to oxidize to a carboxylic acid group’
Why is the reducing power of glucose less than expected?
glucose straight chain form is in equilibrium with its cyclic form
true or false; equilibrium heavily favors these cyclic forms
true
What are the most abundant type of ologosaccharides?
disaccharides
why doesn’t ologosaccharides exist in equilibrium forms
one of the sugars is fixed in either alpha or beta form
What do the polysaccharide chains differ in?
- identity of reccuring monosaccharide units
- length of their chains
- types of bonds linking the units
- degree of branching of the chains
glucose + glucose =
maltose
glucose + galactose =
lactose
glucose + fructose =
sucrose
What are the most abundant polysaccharides?
starch and cellulose
Describe cellulose structure
B 1-4 linkages
insoluble
structural polysaccharides
parallel bundles
what is the most common form of carbohydrate occurring in nature (D or L)
D form
Describe starch
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)
Why is solubility important for starch?
so that it will be able to be hydrolyzed by enzymes to yield glucose
Describe amylopectin
a 1-6 branch points
Describe glycogen
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
Describe chitin
structural polysaccharide
found in exoskeletons of anthropods
similar to cellulose (but contains nitrogen appendage on each glucose)
linkage beta 1-4
define epimer
type of diastereomer that differs only in configuration at 1 chirality center
Define anomer
differ in orientations of one group (open chain forms exist in equilibrium with closed ring forms)
Define enantiomer
have opposite configuration at all chirality centers (mirror images )
Define diastereomer
oppposite configuration at some chiral centers; but same configuration in others
Define stereoisomer
same molecular formula; differ in 3D organisation of atoms in space
Define chirality
- non super imposable
- 4 different groups attached to central atom
rule of stereoisomers
2n (n are # of chirality centers)
Describe amylose
has only alpha 1-4 linkages
helix shape
no alpha 1-6
