2.1.2 polysaccharides

Question 1

describe the structure of starch

Answer 1

alpha glucose mols bonded by 1,4 and 1,6 glycosidic bonds
made of two types of polysacc.
amylose = 1,4 glycosidic bonds; unbranched mol
amylopectin = 1,6 glycosidic bonds, branched mol

Question 2

describe the function of starch

Answer 2

energy store in plants; made by photosynthesis

Question 3

explain the structure of amylose

Answer 3

alpha glucose joined by 1,4 glycosidic bonds
unbranched
angle of bonds = kink into helix shape
very compact; stores more E
insoluble; no osmotic effect

Question 4

explain the structure of amylopectin

Answer 4

alpha glucose forms 1,4 and 1,6 glycosidic bonds; branched molecule, occuring approx every 25 glucose mols
branches = rapid release of glucose; good for resp

Question 5

describe the structure of glycogen

Answer 5

alpha glucose mols joined by 1,4 and 1,6 glycosidic bonds
more branches than starch
branches = free ends to add/remove glucose
extremely compact; maximised storage

Question 6

what is the function of glycogen

Answer 6

energy store in animals

Question 7

describe the structure of cellulose

Answer 7

beta glucose mols joined by 1,4 glycosidic bonds
every alternate molecule is inverted
straight chain molecule; unable to form branches due to inverted mols

Question 8

explain how cellulose molecules join to form larger structures

Answer 8

cellulose mols form cross links = microfibrils
microfibrils form macrofibrils
macrofibrils form cellulose fibres

Question 9

explain the properties of cellulose

Answer 9

hard to hydrolyse (break down)
insoluble = make cell walls + provide structural support to cell
provides roughage for digestion