Carbohydrates Flashcards
3 common monosaccharides
Glucose
Galactose
Fructose
What is a monosaccharides
The monomer from which larger carbohydrates are made
What does the condensation reaction between two monosaccharides form which bond
A glycosidic bond
What two monosaccharides condense to form maltose
Two glucose molecules
3 different disaccharides
Maltose
Sucrose
Lactose
What two monosaccharides condense to form sucrose
Glucose molecules + fructose molecule
What two monosaccharides condense to form lactose
Glucose molecule + galactose molecule
How many isomers does glucose have
What are they called
2
Alpha and beta
How are polysaccharides formed
The condensation of many glucose units
How are glycogen and starch formed
The condensation of a-glucose
How is cellulose formed
The condensation of b-glucose
Formula glucose
C6H12O6
What are sugars with 6 carbon atoms called
Hexose sugars
What are single sugar molecules called
Monosaccharides
Key feature of monosaccharides with water + why
They are soluble in water
Large number OH groups ( hydroxyl group) these can form hydrogen bonds with water molecules so are soluable
What does hydrophilic means + what this mean the molecule does
Water loving
All hydrophilic molecules dissolve in water
What is a pentose monosaccharide
Contains 5 carbor atoms
Example of a pentose monosaccharide
Ribose
What type of monosaccharide is glucose
Hexose monosaccharide
How to tell difference between a-glucose and b- glucose
If the hydroxyl group (OH) is above H the it is b-glucose
If the hydroxyl group (OH) is below H the it is a-glucose
How do disaccharides form
When two monosaccharides chemically react together
a-glucose + a-glucose =
Maltose
What do we also produce when we make a disaccharides + how
Water
Hydrogen atom + hydroxyl atom
What happens during a hydrolysis reaction (to do with saccarides)
Water is added to the disaccharides
To break glycosidic bond
convert it back into two monosaccharides
How many and which side flips from alpha to beta
Right hand side OH above BUT ONLY ON 1 SIDE
Test for reducing sugar
Heat Benedict sample in water bath to 50 degrees
Stays blue - negative
Brick red - positive.
Test for non-reducing sugar
Performed test for reducing sugar.
If negative ….
Heat new sample in dilute hydrochloric acid
Neutralise by adding sodium hydrogen carbonate
Heat sample with Benedict’s
Same policy
Stays blue- negative
Brick-red - positive
Test for starch
Add iodine SOLUTION
Negative - stays orange/brown
Positive - blue- black
