3.1.2 Polysaccharides, 3.1.3 Lipid Flashcards
Structure and the function of starch
In plant cell wall in form of small granules
Energy store in plant
Made of alpha glucose
Coiled and branched
E,g. Amylose, amylopectin
- Insoluble;
- Don’t affect water potential;
OR - Helical;
Accept form spirals - Compact;
OR - Large molecule;
- Cannot leave cell.
● Coiled and branched so it is compact for granule storage
● It is a large insoluble molecule so it is osmotically inactive
● It is branched so glucose is easily hydrolysed for use in respiration
● It is a large molecule so it does not cross the cell membrane and leave the cell
Why is sugar store in starch not glucose?
Starch is insoluble in blood
Glucose dissolve, lower the water potential
water potential is higher outside so water get in by osmosis and make this outburst
Glycogen structure and function
In animal cell
Form by monosaccharides alpha glucose
Similar to amylopectin
Very branched structure
Energy storage in animal
Store in small granules with like starch (muscle and liver)
● Coiled and branched so it is compact for granule storage
● It is a large insoluble molecule so it is osmotically inactive
● It is branched so glucose is easily hydrolysed for use in respiration
● It is a large molecule so it does not cross the cell membrane and leave the cell
Similarly in structure and function of starch and glycogen
Coiled- compact (store in very little space)
Branched (more end , faster process of hydrolysis in respiration for energy release)
Large and insoluble (do not diffuse out of the cell, and osmotically inactive)
Structure and function of cellulose
- Provide strength
- In plant cell wall
- long straight chain
- Become linked together by many hydrogen bonds to form fibrils;
Beta glucose
Every other glucose molecule its rotated by 180° (position of hydrogen and hydroxyls group on carbon atom 1 inverted)
Straight and unbranched
The chain run parallel to each other , hydrogen bonds form between OH groups on adjacent parallel chain, making cross-linkage
Microfibrils- macrofibrils- cellulose fibre- cell wall
Function of cellulose in cell wall
Provides strength
Prevent plant cell burst when water enter by osmosis
Maintain turgidity to maximise service area for absorption of sunlight for photosynthesis
Atom making up of lipid
Carbon, hydrogen, oxygen
Nonpolar molecule (insoluble in water), soluble in organic solvent
Two. Groups of lipid
Triglycerides (fat/oil)(diet) [glycerol, 3 fatty acid]
Phospholipid (cell membrane) [glycerol, 2 fatty acid, phosphate]
solution use for starch test
Iodine in potassium iodide
Emulsion test
Mix three drops of sample with 5CM cube of ethanol in test tube
Shake it with bung on top
Add cold, water and shake gently
Milky white emulation indicate the presence of lipid
Either dissolve the sample or grind and crush first
Saturated and unsaturated lipid
Saturated lipid: close, regular structure, need more energy to brick bond, higher melting point
Unsaturated lipid : push apart, irregular structure, need less energy to break down the bond between them lower melting point
Contains double bond between (adjacent) carbon atoms in hydrocarbon chain.
Role of lipid
Source of energy (more than carbon hydrates)
Waterproof (hydro phobic)— waxy cuticle
Insulation (Slow contactor of heat, retain body heat)
Protection around dedicate organ (kidney)
Buoyancy (less dense than water)
Electrical insulator surrounded nerves to increase speed of electrical impose
why the water potential of apple juice decrease when apple are stored
startch is hydrolysed
maltase is soluble, starch is soluble
the structure of starch is similar to cellulose.
- Are polymers / polysaccharides / are made of monomers / of
monosaccharides; - Contain glucose / carbon, hydrogen and oxygen;
- Contain glycosidic bonds;
- Have 1−4 links;
- Hydrogen bonding (within structure).
Ignore reference to H bonds between cellulose molecules
Explain why monitoring the pH of the mixture could show whether lipid is presence (if lipase is present)
1.Hydrolysis of lipids produces fatty acids;
2. Which lower pH of mixture.
How fatty acids are important in the formation of new cells. In membrane and respires for energy
Fatty acids used to make phospholipids;
Phospholipids in membranes;
More phospholipids more membranes made;
Fatty acids respired to release energy;
More triglycerides more energy released;
Energy used for cell production / production of named cell component;
Definition of monomer
A small repeating unit/ molecule from which larger molecule/ polymer are made
