3.1.2 Carbohydrates Flashcards
Monosaccharide definition
Monomers from which larger carbohydrates are made
Examples of monosaccharides
glucose
galactose
fructose
Examples of disaccharides
maltose
sucrose
lactose
Maltose
glucose + glucose
Sucrose
glucose + fructose
Lactose
glucose + galactose
Carbohydrate
Bonds
Glycosidic bond
-condensation reaction between the hydroxyl groups (elimination of a water molecule)
Give the position of the H in alpha glucose
H
OH
Give the position of the H in beta glucose
OH
H
Polysaccharide Definition
A polymer composed of many saccharide units
Polysaccharide Examples
glycogen
starch
cellulose
Glycogen
Location
Animals
(e.g. muscle, liver) and fungi
Glycogen
Structure
Alpha glucose
Contains CHO
Branched
Glycosidic bonds (1,4 and 1,6)
└condensation reaction
Glycogen
Structure to function
Energy store (glucose) in animals
Insoluble
=water potential not affected= water doesn’t diffuse into/out of cells by osmosis
Large
=doesn’t diffuse out of cells
Branched
=many ends for enzymes to act on= quickly hydrolysed to alpha glucose for respiration
Starch
Location
plants
Starch
Structure
Alpha glucose
Amylose
Unbranched, helical
Glycosidic bonds (1,4)
└condensation reaction
Amylopectin
Branched
Glycosidic bonds (1,4 and 1,6)
└condensation reaction
Starch
Structure to function
Energy store (glucose) in plants
Insoluble
=water potential not affected= water doesn’t diffuse into/out of cells by osmosis
Large
=doesn’t diffuse out of cells
Branched
=many ends for enzymes to act on= quickly hydrolysed to alpha glucose for respiration
Helical
=compact= can store many molecules in a small space
Cellulose
Location
Plants
Cell walls
Cellulose
Structure
Beta glucose
Unbranched
Glycosidic bonds (1,4)
└condensation reaction
Molecules rotate 180 degrees relative to its neighbour
Adjacent chains linked by hydrogen bonds to form microfibrils
Cellulose
Structure to function
Strengthens cell walls/ prevents them from bursting
Unbranched
Straight chain linked by H bonds → myofibrils
= increase strength
Reducing sugars
-a sugar that can donate an electron to a substance to reduce it
-e.g. all monosaccharides (glucose), some disaccharides (maltose, lactose)
└NOT sucrose
Benedicts test for reducing sugars
Add benedicts reagent in excess and heat
+) brick red precipitate (green →yellow →orange
Comparing the amount of reducing sugars in different concentrations
Observe colour change (less accurate)
-darker= more concentrated
Use a colorimeter (more accurate)
- filter solution and weigh precipitate
- use colorimeter to measure absorbance of remaining benedict’s reagent
Benedicts test for non- reducing sugars
-add benedicts reagent in excess and heat
(-) blue
-heat new sample with dilute HCL acid/ hydrolytic enzyme (to hydrolyse)
-add sodium carbonate (to neutralise)
-add benedicts reagent in excess and heat
(+) brick red precipitate (green →yellow →orange)
