1.3 Flashcards
Where is starch found and what it’s its role?
Starch is found in plants as small grains, mainly in seeds and storage organs eg. potato tubers. The main role of starch is energy storage
What properties make starch suitable for energy storage and why?
1)Insoluble – does not draw in water by osmosis/does not affect the osmotic balance in cells
2)Compact – many can be stored in a small space
3)Hydrolysis easily to form α-glucose – this is readily transported and used in respiration
What is starch made of?
Starch is made of two types of polysaccharides, amylose and amylopectin, both of which are made from repeating units of α-glucose joined together by condensation
Which glucose molecule is amylose made from? branched or unbranched?
alpha glucose molecules which are un- branched
what bonds are present in amylose and its shape?
- there are only 1-4 glycosidic bonds present
- wound into a tight coil, making the molecule compact and ideal for storage
Amylopectin is made from which glucose molecule and is it branched or unbranched?
alpha glucose molecules and they are branched
What bonds are present in amylopectin and what’s its shape?
- there are 1-4 and 1-6 glycosidic bonds present
- and it’s more globular in shape
What is glycogen and where is it found?
Glycogen is a storage molecule found in animals, mainly in the muscles and liver
What is it and what is it made from?
It is a polymer made from repeating alpha glucose subunits that branch
3 properties of glycogen?
1)Insoluble so does not draw in water by osmosis/does not affect the osmotic balance in cells
2)Compact so many can be stored in a small space
3)Made of smaller chains than amylopectin so more easily hydrolyses to form α-glucos
Where is cellulose found and what is it used for?
Found in plants and used for structure and strength
What is it and what is it made up of?
It is a polymer made from repeating beta glucose subunits
How are glycosidic bonds formed in cellulose?
• In β-glucose the OH group is above the ring so to form a glycosidic bond each β-glucose must be rotated 180degrees compared to the next one
What do condensation reactions result in regarding cellulose?
Condensation reactions link carbon atom 1 to carbon atom 4 on the NEXT β-glucose.
This results in straight unbranched chains
Fibers and microfibrils?made from?
Cellulose chains are grouped together to form microfibrils, which in turn make macrofibrils/fibres
