Variation in Carbohydrates Flashcards
What is starch?
A polysaccharide that is found in many parts of a plant in the form of small grains.
It is the main energy storage material.
Cells get energy from glucose, and plants store excess glucose as starch.
What is the structure of starch?
It is made up chains of alpha glucose monosaccharides linked by glycosidic bonds that are formed by condensation reactions.
It is a mixture of two polysaccharides of alpha glucose- amylose and amylopectin.
What is amylose?
A long, unbranched chain of alpha glucose, the angles of the glycocidic bonds are different between two alpha glucose molecules than they are between two beta glucose molecules and so it has a coiled structure which makes it compact and good for storage.
What is amylopectin?
A long, branched chain of alpha glucose.
Its side branches allow the enzymes that break down the molecule to get at the glycosidic bonds easily meaning that the glucose can be released quickly.
Why is starch suited for its role in energy storage?
It is insoluble and therefore does not tend to draw water into the cells by osmosis.
Being insoluble it does not easily diffuse out of cells.
It is compact, so a lot of it can be stored in a small space.
When hydrolysed it forms alpha glucose which is both easily transported and readily used in respiration.
What is glycogen?
The main energy storage material in animals.
Animal cells get energy from glucose, which is from stored excess glucose as glycogen- another polysaccharide of alpha-glucose.
What is the structure of glycogen?
Very similar to starch but has shorter chains and is more highly branched.
Why is glycogen suited to its role in storage?
Same as starch however, because it is made up of smaller chains, it is even more readily hydrolysed to alpha glucose.
What is cellulose?
The major component of cell walls in plants, its made of long unbranched chains of beta glucose.
What is beta glucose?
Glucose is a monosaccharide with two forms- alpha and beta. Beta glucose is basically the same as alpha glucose by the OH and H on the right are swapped around.
What is the structure of cellulose?
The bonds between the sugars are straight, so the cellulose chains are straight.
The cellulose chains are linked together by hydrogen bonds to form strong fibres called microfibrils.
The strong fibres mean cellulose provides structural support for cells.
