Chapter 2 - Carbs Flashcards
(45 cards)
What is starch?
A polymer of alpha glucose, linked with many glycosidic bonds
What shape is starch?
It coils in to a ring due to the bonding of the C1 of a glucose to the C4 of the next a (1,4 glycosidic bond)
What two molecules make up starch?
Amylose (straight chain that coils) and amylopectin (a long branched chain with short arms of glucose units ( 1,6 bond))
Is a starch molecule stable?
Yes, due to the coiling and folding (individual glycosidic bonds are weak)
How do you test for starch?
Iodine, gives blue black colour when present
What is the purpose of starch?
Major carbohydrate storage molecule in plants
What is starch stored in, in plants?
Amyloplasts (a type of plastid)
What is a plastid?
A specialised membrane bound organelle found in plant cells e.g. chloroplasts & amyloplasts
What is glycogen?
A polymer of alpha glucose with more branches than starch (amylopectin) and shorter chains
What is the purpose of glycogen?
A source of stored energy in animals, easily broken down into glucose when needed and stored in liver & muscle cells
What is cellulose?
Made of beta glucose, which are also joined by glycosidic bonds
What is the difference between beta and alpha glucose?
The H group is ‘ABOVE in ALPHA’ and the H group is ‘BELOW in BETA’
Why is the polymer of cellulose different to that of glycogen or starch?
Because of the OH and H arrangement in beta glucose (h at the bottom), the alternating beta molecules must be flipped so that they can bond
How do cross links form in cellulose?
The alternating beta molecules form a very straight chain with many -OH groups on the outside, allowing hydrogen bonds to form between adjacent cellulose chains
What do the cross links between different cellulose chains allow?
Allows cellulose to form cellulose microfibril, which cross links to form cellulose fibres
What are three examples of polysaccharides?
Starch, glycogen and cellulose
What is the function of cellulose?
Strengthens and stabilises plant cell walls
What are polysaccharides?
Large polymers formed of many monosaccharides that are combined by condensation reactions
In a polysaccharide how is each polymer attached to the chain?
By a glycosidic bond
Why do simple sugars release energy?
Because they are small simple molecules which and soluble
Why are complex carbs used as energy stores and not for instant energy release?
Because they are large complex molecules which are stable and insoluble
What three types of carbs are there?
Monosaccharides, disaccharide, polysaccharide
Three examples of monosaccharide molecules?
Glucose (6C), ribose (5C), Deoxyribose (5C)
What is the function of glucose?
A source of energy (easily hydrolysed), transported in the blood of animals
