What are the monomers called in carbohydrates?
Monosaccharides
What are carbohydrates used for?
Energy source / store (glucose, starch, glycogen)
Structure (cellulose)
Give some properties of monosaccharides
Small molecules - easily absorbed and transported
Highly soluble
What is the difference between alpha and beta glucose?
On beta glucose the OH on the carbon 1 is at the top, on alpha it is at the bottom.
What elements do all carbohydrates contain?
Oxygen, hydrogen and carbon
What is a disaccharide?
A carbohydrate that has two monosaccharides joined together (by a glycosidic bond)
What is maltose hydrolysed by and into what?
Maltase into two glucose molecules
What is sucrose hydrolysed by and what into?
Sucrase into glucose and fructose
What is lactose hydrolysed by and what into?
Lactase into glucose and galactose
How are disaccharides formed?
By a condensation reaction between two monosaccharides (produces water)
How are disaccharides split up into two monosaccharides?
By a hydrolysis reaction (add water)
What is the bond called between monosaccharides?
Glycosidic bond (it is a covalent bond)
What is the formula of a disaccharide?
C12H22O11 (water produced)
What is starch made up of?
Amylose and amylopectin
What carbons are the glycosidic bonds between in disaccharides?
Carbon one and four
What is a polysaccharide?
Many monosaccharides joined together by glycosidic bonds
Give two examples of polysaccharides
Amylose
Amylopectin
Cellulose
What is lactose intolerance?
If you do not have enough lactase (enzyme) you cannot breakdown lactose (in milk) this is called lactose intolerance
What and how is caused by lactose intolerance?
Undigested lactose builds up in the small intestine it is fermented by bacteria producing gas causing stomach cramps, flatulence and diarrhoea
Also, the build up of lactose in the small intestine causes the solute concentration of the lumen to rise and the water potential to lower, this means water moves out of cells into the SI lumen via epithelial cells down the concentration gradient via osmosis. This build up of water causes diarrhoea
How can you prevent conditions from lactose intolerance?
Artificially treat milk with purified lactase to make it suitable (it is already digested)
What is the formula of glucose / monosaccharides?
C6H12O6
What and how is the test for reducing sugars?
The Benedict’s test
Heat solution with Benedict’s reagent. If it changes from blue to brick red then reducing sugar is present
If it stays blue we can test for non-reducing sugar. Get a new sample, boil it with dulce hydrochloric acid, then neutralise it by adding sodium hydrogencarbonate. Do the same as the first step
How is starch digested?
As it is made up of a mixture of polysaccharides, more steps are needed to break it down.
First it is broken down by amylase in the mouth to form maltose, then by maltose to form alpha glucose molecules
What and how is the test for starch?
Iodine test
Add iodine dissolved in potassium iodide solution into the sample. If starch is present, the sample changes from browny orange into a dark, blue-black colour
