Carbohydrates Flashcards
What do monosacchardies make up?
Disaccharides and polysaccharides
What are examples of polysaccharides?
Cellulose, starch and glycogen
What is the general formula of monosaccharides?
(CH2O) n
What is the difference between a-glucose and b-glucose?
The position of thr OH group (a- glucose on the bottom right and b- glucose on the tip right
What monosaccahrides make up maltose?
a-glucose + a-glucose
What monosaccharides make up sucrose?
Glucose + fructose
What monosaccahrides make up lactose?
Glucose + Galactose
What type of bond does a glucose molecules form?
Glycosidic bond
How is a glycosidic bond formed?
Via a condensation reaction between two monosaccharides
What is a glycosidic bond?
The oxygen that links between two monosaccahrides
What is a single monomer of a carbohydrate?
Monosaccharide
How do you test for Reducing sugars?
1) Add 2cm^3 of the food sample to a test tube.
2) Add an equal volume of Benedict’s solution.
3) Heat the mixture in a water bath at 80 degrees for 5 minutes.
- If the solution has turned orange/ brown, a reducing sugar is present.
What is a reducing sugar?
A sugar that can donate electrons to another chemical.
How do you test for a non- reducing sugar?
1) Add 2cm^3 of food sample witb equal volume of benedicts reagent.
2) gently heat at 80 degrees for 5 minutes.
- If the solution does not change colour:
3) Take 2cm^3 of the food solution with 2cm^3 of dilute hydrochloric acid.
4) place back in water bath for 5 minutes at 80 degrees
5) Add a few drops of sodium hydrogencarbonate and then test using pH paper. (It should be alkaline)
6) Add 2cm^3 of benedicts solution and heat at 80 degrees for 5 minutes.
How do you test for starch?
1) Place 2cm^3 of the sample into a test tube and add two drops of iodine.
2) Shake the tube.
The colour will now turn for orange to blue/ black.
What type of glucose is starch made up off?
Starch is a polysaccharide made up off a-glucose monosaccharides
What are the main roles of starch?
- Insoluble
- Does not diffuse out of cells
- Compact
- Many branched ends.
- Can be easily hydrolysed.
Does glycogen have more or less branched than starch and cellulose?
More highly branched with shorter chains than starch and cellulose (unbranched)
Why can starch molecules form a coil shape?
Due to the hydrogen bonds that form between the OH groups.
Why is it an advantage that starch is insoluble?
Doesn’t affect water potential within the cells, meaning that no osmosis can occur.
Why is it an advantage that starch is large and insoluble?
So that it does not diffuse out of cells.
Why is it an advantage that starch is compact?
So that lots of it can be stored in small spaces.
What are three differences between Starch and Glycogen?
- Glycogen is found in animals whereas starch is found in plants.
- Glycogen is more highly branched than starch.
- Glycogen is more easily hydrolysed as animals require more energy than plants.
What type of monomer is cellulose made out of?
B- Glucose
