Carbohydrates Flashcards
which monomers form carbohydrates
monosaccharides
Three monosaccharides
Glucose, galactose, fructose
Formula of monosaccharides
C6H12O6
bond formed due to the condensation reaction between two monosaccharides
glycosidic bonds
2 glucose isomers
alpha glucose and beta glucose
Definition of isomer
A substance with the the same chemical formula but a different structural formula
condensation reaction between two monosaccharides
between the OH group of carbon 4 of one and the Carbon 1 group of another.
It forms a 1-4 glycosidic bond
3 dissacharides
maltose,lactose,sucrose
the monosaccharides which form maltose
alpha glucose + alpha glucose
the monosaccharides which form lactose
galactose and glucose
the monosaccharides which form sucrose
glucose and fructose
What happens to carbohydrates in digestion
they are broken down into monosaccharides to be absorbed and used by the body.
Use of monosaccharides in the body
glucose is needed for respiration.
reducing sugars
glucose, galactose,lactose,maltose and fructose
non reducing sugar
sucrose
test for reducing sugars
heat the sample in Benedict’s solution to 95 degrees Celsius.
observe a colour change fro, BLUE to green/yellow/orange/red.
test for non reducing sugars
boil fresh sample in HCl for a few minutes to hydrolyse the glycosidic bonds.
neutralise by adding solid sodium hydrogen carbonate.
then repeat the test for reducing sugars (describe fully in exam)
as the sucrose is hydrolysed into glucose and fructose which are reducing sugars.
The colour change will be from blue to brick red.
test for starch
add iodine solution (potassium iodide) and there will be a colour change from orange to blue-black
