Monosaccharides definition?
That monomers from which larger carbohydrates are made
Polysaccharides definition?
Polymers created by many condensation reactions between many glucose monomers
- glycogen & starch - alpha
- cellulose - beta
Starch?
- formed from 2 polymers of a glucose: Amylose & amylopectin
- found in form of starch grains/grains inside plant cells
- function: insoluble energy storage of glucose in plants
- structure: coiled and branched (due to the presence of 1-4 and 1-6 glycosidic bonds)
Structure of amylose?
-1-4 glycosidic bonds between monomers
- chains form coiled shape
- Unbranched chain of amylose coils up to make a helix/spiral
Structure of amylopectin?
- 1-4 and 1-6 glycosidic bonding between monomers
- branched shape due to 1-6 glycosidic bond
Relationship of structure to function for starch and glycogen?
- Starch: Coiled so is compact (a lot can be stored in very little space)
- both: branched so more ends for faster hydrolysis of glucose molecules - to be used in respiration for energy release (larger SA for enzymes)
Glycogen?
- formed from a glucose
- found in muscle and liver cells in animal
- Also stood in small granules like starch
- function: Insoluble energy store of glucose in animals
Structure: (Very similar structure to amylopectin in starch) - BUT is highly branched - Less 1-4 glycosidic bonds and more 1 - 6
Cellulose?
Function: structural role (provides strength) - found in plant cells
- B glucose
- Only one to four glycosidic bonds - creates long straight unbranched chains of B glucose
- Chains lie parallel to each other - then held in place by many H bonds aka a “fibril”
- B glucose: (Small change OH group on C1 causes huge differences in the structure and function)
- Every other glucose molecule is rotated by 180 degrees to allow the glycosidic bonds to form between the beta glucose molecules
Relationship of Structure to function of cellulose?
- B glucose chains run parallel to each other & H bonds form between OH groups on adjacent parallel chains - forming cross linkages aka microfibrils
- microfibrils ->H bond together to form macrofibrils -> then H Bond together to form cellulose fibres
- cellulose fibres are what make up the cell walls in plants
- this formation results in cellulose being very strong - providing strength in cell walls
- H Bonds collectively provide strength to cell wall
All three are insoluble?
- Doesn’t affect the water potential of cells so osmosis- won’t have excess water moving in or out of cell - burst
Function of cellulose in cell walls?
- Provides strength in cell walls
- Prevents plant cells bursting when water enters by osmosis
- Maintains turgidity and rigidity in plant cells and therefore in the whole plant (stems and leaves)
- Maximises surface area for light absorption for photosynthesis
