1.3- CARBOHYDRATES- DISACCHARIDES AND POLYSACCHARIDES Flashcards
What does glucose joined to glucose form?
maltose
What does glucose joined to fructose form?
sucrose
What does glucose joined to galactose form?
lactose
When the monosaccharides join, a molecule of water is removed, what is the reaction?
condensation reaction
What is the bond formed called?
glycosidic bond
What is it called when water is added to disaccharide under suitable conditions and it breaks the glycosidic bond releasing the constituent monosaccharides?
hydrolysis
E.g. of disaccharides that are non-reducing sugars?
sucrose
What are non-reducing sugars?
do not change colour of Benedict’s reagent when heated with it
What must be done in order to detect a non-reducing sugar?
must be first hydrolysed into its monosaccharide components by hydrolysis
What are polysaccharides?
polymers formed by combining together many monosaccharide molecules
How are the monosaccharides joined by?
glycosidic bonds
Property of polysaccharides as they are very large molecules?
insoluble
How does them being insoluble fit them for a certain purpose?
for storage
What happens when polysaccharides are hydrolysed?
break down into disaccharides or monosaccharides
Type of polysaccharide not used for storage and purpose?
cellulose
give structural support to plant cells
What is starch?
polysaccharide found in many parts of plants in form of small granules or grains
Example of where starch can be found
starch grains in chloroplasts
How is starch formed?
joining of between 200 and 100 000 α-glucose molecules by glycosidic bonds in a series of condensation reactions
How is starch easily detected?
its ability to change colour of iodine in potassium iodide solution from yellow to blue-black
What temperature is the test for starch carried out in?
room temperature
