1.2 CARBOHYDRATES Flashcards
What are monosaccharides?
Monomers from which carbohydrates are made.
What are some examples of monosaccharides? (3)
- Glucose
- Fructose
- Galactose
How do you join two monosaccharides together?
A condensation reaction
What is the bond between two monosaccharides called?
Glycosidic bond
What is a disaccharide?
Two monosaccharides joined together by a glycosidic bond.
What is maltose made of?
Glucose & Glucose
What is sucrose made of?
Glucose & Fructose
What is lactose made of?
Glucose & Galactose
What is the difference between the π/Ξ² glucose structures?
(see notes for image)
π: hydroxyl group below the oxygen
Ξ²: hydroxyl group above the oxygen
What is a polysaccharide?
Multiple monosaccharides joined together by glycosidic bonds.
What is cellulose made of?
chains of Ξ² glucose
What is starch/glycogen made of?
chains of π glucose
What is the structure of starch?
- Has unbranched glucose chains, so compact.
- Also has some branched glucose chains.
- Very compact structure
What is the function of starch?
- Insoluble and big so can be stored.
- Compacts so lots can be stored in small places
- Branched glucose chains allow enzymes to act of them quickly, to release lots of glucose.
- Used for storage in plants
What is the structure of glycogen?
- Has very branched glucose chains.
- Has unbranched glucose chains, so compacted.
What is the function of glycogen?
- Storage molecule for animals.
- Insoluble and big so can be stored.
- Compacts so lots can be stored in small places
- Branched glucose chains allow enzymes to act of them quickly, to release lots of glucose.
What is the structure of cellulose?
- Straight, unbranched chains.
- Chains run parallel to one another.
What is the function of cellulose?
- Chains running parallel are held together by H bonds.
- Makes these chains very strong.
- Cellulose molecules can clump together into fibres to make them stronger.
- Used for plant cell walls.
Outline the test for reducing sugars
- Add x volume of sample into test tube.
- Dissolve this in water.
- Add an equal (x) volume of Benedicts reagent.
- Heat the mixture for 5 minutes.
What are the observed colour changes for the reducing sugars test?
blue (no reducing sugars)
green - red (reducing sugars)
Outline the test for non-reducing sugars?
- Add x volume of sample into equal volumes of HCl.
- Heat in a water bath for 5 minutes.
- Add NaHCOβ to neutralise the acid.
- Then carry out the reducing sugars test on this sample.
Why do you add HCl to you non-reducing sugar sample first?
HCl hydrolysed the polymer, breaking it up into its reducing sugar monomers.
What is a reducing sugar?
A sugar that can donate electrons.
Which sugars are reducing?
- All monosaccharides
- Maltos & Lactose (disaccharides)
