Carbohydrates Flashcards
Describe the structure of an alpha glucose
Hexagon. On the top is ch2oh. On carbon 1 and 4 the h is up and the oh is down
Describe the structure of beta glucose
On carbon 4 h is up and oh is down. On carbon 1 oh is up and h is down
Describe condensation reactions
When two molecules join together covalently and as the reaction occurs a water molecule is formed
What is the bond between monosaccharides called
A glycosidic bond
What is a hydrolysis reaction
A molecule of water is added and the covalent bond is broken
Properties of lactose
Made from glucose and galactose
1,4 glycosidic bond
Present in milk and important in infants diets
Properties of sucrose
Made from glucose and fructose
1,2 glycosidic bonds
Present in sugar cane
Way in which sugar is transported in plants
How are disaccharides hydrolysed
By using enzymes or by heating in acid eg HCl
What is maltose made from
Two glucose molecules
What are starch and glycogen polymers of and how are the monomers joined
Alpha glucose monomers
Condensation reaction
What is the function of both starch and glycogen
To store glucose molecules within cells
Starch=plant
Glycogen=animal
Properties of both starch and glycogen
Compact-don’t take up too much space in cell
Insoluble- can’t be lost from cells by dissolving
No osmotic effect- don’t pull water into cell
Easily hydrolysed- release glucose when needed for respiration
What are the two forms of starch
Amylose and amylopectin
Structure of amylose
- chains of alpha glucose joined by 1,4 bonds therefore it is unbranched
- coils into helix held by hydrogen bonds
Structure of amylopectin
- branched chain of alpha glucose (new branches only at the beginning)
- has 1,4 and 1,6 glycosidic bonds
- helix
Structure of glycogen
-highly branched
- helix
- 1,4 and 1,6 bonds, branch points every 8-12 glucose (more branches =more ends=hydrolysed quicker= more glucose related for respiration)
Properties of cellulose
High tensile strength- resits large pulling force
Insoluble and flexible- good for building cell walls
Strong- resists turgar pressure
Resisitant to human digestion- needs a specific enzyme
Structure of cellulose
Polymer of beta glucose, unbranched
In the chain glucose number 2,4,6 etc is flipped to allow the oh groups to match up
Microfibrils- individual chains held adjacently by hydrogen bonds
Fibres- microfibrils bound together
Cell wall- fibres laid down on top of eachother in many directions
Test for starch
Iodine in potassium iodide solution
Orange/brown to blue /black if starch is present
Test for protein
Biruets
Blue to purple
How does the biruets test work
Add biruets reagent ( sodium hydroxide and copper sulphate)
A complex forms between the N atoms on the peptide chain and the Cu2+ ions
Test for reducing sugars
Benedicts
Heat in boiling water bath
Low level of sugar = blue/green
Medium = orange
High=brick red
