3.1.2 Carbohydrates Flashcards
What is a condensation reaction?
-between two monosaccharides
-forms glycosidic bond
What does a condensation reaction release?
water
How is maltose made?
condensation of 2 glucose molecules
How is sucrose made?
condensation of a glucose and fructose molecule
Sucrose is a…
disaccharide
How is lactose made?
condensation of a glucose and galactose molecule
How are glycogen and starch formed?
condensation of alpha glucose molecules
How is cellulose formed?
condensation of beta glucose
Structure of starch
-made up of alpha glucose
-linear chain
-alpha 1,4 glycosidic bonds
-coiled/ helical
Structure of glycogen
-made up of alpha glucose
-branches
-alpha 1,4 glycosidic bonds AND alpha 1,6 glycosidic bonds
-spherical
Cellulose structure
-made up of beta glucose
-linear chain
-Beta -1,4- glycosidic bonds
-alternate glucose molecules inverted
-Hydrogen bonds form between adjacent chains (microfibrils)
Amylose and glycogen are polymers of alpha glucose so…
can provide respiratory substrate
Amylose is helical so is…
more compact (more can be stored in cell)
Glycogen is spherical so is…
more compact (more can be stored in cell)
Glycogen is branches so…
can be hydrolysed more rapidly
Amylose and glycogen are insoluble so…
do not affect movement of water into cell by osmosis
Amylose and glycogen are large molecules so…
cannot diffuse out of cell
Cellulose has Hydrogen bonds between adjacent chains so…
provides high tensile strength and flexible cell walls
Cellulose has straight chains so…
form stronger fibres and are closely packed
How to test for amylose (starch)
-add iodine
-turns from orange —-> blue/ black
How to test for a reducing sugar (e.g. glucose, maltose)
-add Benedict’s solution
-heat at 85C in water bath
-turns from blue —-> brick red
(lower conc. = green, yellow, orange)
How to test for non-reducing sugars (e.g. sucrose)
-test for reducing sugars = negative result
-heat sugar solution with HCl
-cool
-neutralise with sodium bicarbonate
-add Benedict’s solution
-heat at 85C in water bath
-turns from blue —-> brick red
