1.2 Flashcards
are homoglycans oligosaccharide, polysaccharide, or disaccharides?
they are considered polysaccharides because they are a polymer
residues
repeating units
sugars
are the only ones that can be branched
monosaccharides
n=1
disaccharides
n=2
oligosaccharides
n=3 to n=10
polysaccharide
n > 10
what are the simplest from of polysaccharides?
disaccharides
polysaccharides are composed of?
they have monosaccharides (at least two) that have a oxygen glycosidic linkage by a covalent bond
describe lactose
- it is a type of disaccharide that has a glycosidic linkage between beta 1 of galactose and beta 4 of glucose.
- because it has a head to tail fashion, it is reducing
- overall: Beta-D-galactopyranosyl (1->4) B-D-glucopyranose
how much of lactose is in milk?
10 (w/w) which means about 10%
think of there being 10 g of it in 100 g
what causes milk to go sour?
lactose is oxidized to lactate by good bacteria called lactobacillus. There is an over concen of them
describe sucrose
it is a oxygen glycosidic linkage between glucose and fructose
-alpha-D-glucopyranosyl (alpha 1 -> beta 2) B-D-fructofuranose
- head to head type of linkage so that would make it a non reducing disaccharides because both of the anomeric carbons are involved
- found in table sugar
describe maltose
it is an oxygen glycosidic linkage between alpha 1 and alpha 4 of glucose molecules
- it is malt sugar and is used in beer productions
- because of its head to tail linkage, it is reducing
- overall: alpha-D-glucopyranosyl (1->4) alpha-D-glucopyranose
describe lactulose
it is an oxygen glycosidic linkage between beta 1 of galactose and beta 4 of fructose
-overall: B-D-galactopyranosyl (beta 1-> beta 4) B-D- fructfuranose
-used as a laxative due to it being a nonabsorbable sugar which causes it to retain water
-
what happens when milk is warmed
lactose is converted into lactulose
describe trehalose
it has a glycosidic linkage between alpha 1 and alpha 1 of glucose causing there to be a head to head collusion
- nonreducing disaccharide
- able to retain water in shrimps and insects
- overall: alpha-D-glucopyranosyl (alpha 1 -> alpha 1) alpha-D-glucopyranose
reducing vs non reducing disacharides
non reducing means that both the anomeric carbons are involved in the glycosidic linkage SO NOTHING CAN PARTICIPATE IN REDUCTION.
reducing means that only one of the anomeric carbons are involved so the other one CAN PARTICIPATE in REDUCTION
name the two classifications of homoglycans
storage and structural
why can homoglycans form linear and branched?
there polyhydroxy allows them to form glycosidic lnkages on the same monosacharide
what are the fuel storage homoglycans?
starch and glycogen
what are the structural component of homoglycans?
cellulose and chitin
what is starch made up of?
linear amylose and branched amylopectin
describe starch
it is used as a energy reservoir for plants especially in chloroplasts
describe amylose
repetitive alpha-D-glucose at the alpha 1-4 linkage bond
describe amylopectin
has linears of amylose and branched glucose of alpha 1 to 6 by every 30 monomers
describe glycogen
has glycosidic linkage of glucose from alpha 1-> 6 but is branched every 10 residues
- fuel storage for animals
- 10% w/w of liver and muscles
what is the most abundant polymer?
cellulose
describe cellulose
it is comprised of beta d glucose and it is linear with extended sheets and is found in plant cell walls
-beta 1-4
chitin
it has N-acetyl-B-d-glucosamine and is linear but with extended sheets at Beta 1-4
found in exoskeletons like crabs
what is the second most abundant polymer?
chitin
