Oligosaccharides & Polysaccharides Flashcards
Define oligosaccharides.
A condensation product of 3-10 monosaccharides
True or False:
Most oligosaccharides are not digested by human enzymes
True
What is another name for raffinose? What is it?
Melitose
Trisaccharide
Define polysaccharide
high molecular weight polymers
Most carbs found in nature occur as
polysaccharides
Polysaccharides are
large molecules of monosaccharides that are connected to each other through their anomeric carbons
- Polysaccharides are condensation products of _____
2. They can be ______ or _____
more than 10 monosaccharide units
linear or branched
3 biologically important polysaccharides are:
starch, glycogen, and cellulose
All 3 (biologically important polysaccharides) are ________ but they differ in the type of ______ ______ and/or the amount of ________
polymers of D-glucose
glycosidic bond
branching
How do polysaccharides differ from each other?
- identity of their monosaccharide units
- length of their chains
- types of bonds linking the units
- degree of branching
What are polysaccharides classified into?
homopolysaccharides
heteropolysaccharides
Homopolysaccharides
when polysaccharides are composed of a single type of monosaccharide building block
Heteropolysaccharides
polysaccharides composed of more than 1 type of monosaccharide
Examples of Homopolysaccharides
starch
glycogen
cellulose
dextrins
Heteropolysaccharides can be divided into
glycoseaminoglycans and mucilages
Examples of glycoseaminoglycans
hyluronic acid
heparin
ABO blood
Examples of Mucilages
- agar
- pectins
- hemicellulose
Starches and dextrins ( polysaccharides)
- digested by human enzymes
- its hydrolysis provide glucose (the most important carb)
Nonstarches (polysaccharides)
not digested by human enzymes and are the major component of dietary fiber
What are the 2 types of polysaccharides?
storage polysaccharides
structural polysaccharides
Storage and structural polysaccharides are made up of _______ _____, but they are _________ and ________ different
glucose units
structurally and functionally
Storage polysaccharides
Name 3
contain only a-glucose units
3 important ones are starch, glycogen, and amylopectin
Structural polysaccharides
Name 2
contain only B-glucose units
2 important ones are cellulose and chitin
Chitin contains a
modified B-glucose unit
Function of Starch
the main storage form of glucose in plant cells
Structure of Starch
its structure is identical to glycogen except for a much lower degree of branching (ab every 20-30 residues)
Pure starch is …………
Powder that is ………
Found in ………..
Gives blue color with ………..
white, tasteless, and odorless
insoluble in cold water
wheat, rice, corn, potatoes
iodine
What is amylose?
a glucose polymer with a(1–>4) linkages
What is amylopectin?
a glucose polymer with mainly a(1–>4) linkages, but it also has branches formed by a(1–>6)
Function and Location of Glycogen
- a storage polysaccharide found in animals
- stored in the liver and muscles
Structure of Glycogen
its structure is identical to amylopectin, except that a(1–>6) branching occurs about every 12 glucose units
When glucose is needed, glycogen is
hydrolyzed in the liver to glucose
Function of Cellulose
the main constituent of the plant’s cell wall
Cellulose is
insoluble
Structure of Cellulose
a polysaccharide consisting of a linear chain of several hundred to over 10 thousand B (1–>4) linked B-D-glucose units
Why can some animals digest cellulose? Which animals?
some animals can digest cellulose with the help of bacteria in their stomachs
-ruminants and termites
How do human digest cellulose?
we do NOT have the enzymes needed to digest the bonds in fibers
What can cellulose be called?
What does it act as?
dietary fiber
acts as a hydrophilic bulking agent for feces
What inulin?
Where is it found?
- It’s a polysaccharide of fructose
- its found in tubers and roots of some plants, readily soluble in water
What can inulin be used for?
determining the glomerular filtration rate
Can inulin be hydrolyzed by intestinal enzymes?
no
What are the fructose units in inulin joined by?
a B (2–>1) glycosidic bond
In general, plant inulin polymers contain between
20 and several thousand fructose units
What is chitin?
What is composed of?
- is a structural polysaccharide found in the exoskeleton of insects
- composed of N-acetylglucoseamine units linked by B1–>4 bond
What is dextrin?
the intermediate in the hydrolysis of starch
