polysaccharides Flashcards
what is a polysaccharide
a carbohydrate
how is a polysaccharide formed
when two or more monosaccharides are joined together by condensation reactions
how can polysaccharides broken down
by hydrolysis
what bond to they contain
glycosidic bond
what are three polysaccharides
starch, glycogen and cellulose
what do plants store excess glucose as
starch
what two polysaccharides make up starch
amylose and amylopectin
describe amylose’s structure
long, unbranched chain of alpha glucose. the angles of the glycosidic bonds give it a coiled structure.
describe amylose’s function
Compact so it is good for storage because you can fit more in to a small space
describe amylopectin’s structure
long, branched chain of alpha glucose. Its side branches all the enzymes to break down the molecule to get to the glycosidic bonds easily
describe amylopectin’s function
to release glucose so the plants have energy
how do plants get energy
glucose
true or false starch is soluble in water
False, starch is insoluble in water
why is starch being insoluble in water a good thing?
it means that it doesn’t affect water potential, so it doesn’t cause water to enter cells by osmosis which would make them swell
where do animals get energy from
glucose
what do animals store excess glucose as
glycogen
describe the structure of glycogen
polysaccharide of alpha glucose, lots of side branches
describe the function of glycogen
loads of branches mean that stored glucose can be released quickly, this is important for energy release in animals. it is also compact so is good for storage
describe cellulose’s structure
long, unbranched chains of BETA GLUCOSE, when beta glucose molecules bond they form straight cellulose chains. The cellulose chains are held together by hydrogen bonds to form strong fibres called microfibrils
describe cellulose’s function
cellulose provides structural support for cells due to the strong fibres (microfibrils)
what’s the test for starch
the iodine test
explain the iodine test
add iodine dissolved in potassium iodide solution to the sample
what will a positive test for the iodine test look like
dark blue black colour
what will a negative test for the iodine test look like
browny orange
