Carbohydrates and Lipids Flashcards
Monosaccarides, Disaccardies, Polysaccaradies, lipid Structure, Food Tests
Small identical or similar molecules which can be joined together to make larger molecules called polymers
Monomer
The reaction joining monomer units together with the removal of one water molecule
Condensation reaction
The addition of one water molecule to break the bond between two monomers
Hydrolysis reaction
Sweet tasting, soluble molecules
Monosacchardes
The general fomula of a monosaccharide
C6H1206
3 monosaccharide examples:
. Fructose
. Glucose
. Galactose
2 monosaccharides joined together through a condensation reaction
Disaccharide
Maltose
Glucose + Glucose
Galactose
Glucose + Lactose
Sucrose
Glucose + Fructose
Amylose (starch)
. Long straight chains of alpha glucose that coilt into a helix
. Carbon 1:4 glycosidic bonds
. Compact - good for storage
. Insoluble - doesn’t affect water potential
. Large - does not diffuse
Amylopectin (starch)
. Branched chains of alpha glucose
. Carbon 1:4 and 1:6 glycosidic bonds
. LSA - fast hydrolysis by enzymes = quick energy release
. Insoluble - doesn’t affect water potential
. Large - doesn’t diffuse out of cells
Glycogen
. Found in liver and muscle cells
. Short branched chains provide LSA so is more easily hydrolysed
. Insoluble - doesn’t affect water potential
. Large - doesn’t diffuse out of cell
Cellulose
. Plant cell wall
. Beta glucose in long straight chains
. Every other beta glucose is inverted 180 degrees
. Carbon 1:4 glycosidic bond
. Several chains in layers held together by H bonds formed between OH groups
. Very strong
. The chains make microfibrils which are further wound together to form cellulose fibres - they provide strength and support
Test for carbohydrates
Benedict test
Benedict test for reducing sugar
. Add equal volumes of sample and Benedict solution
. HEAT
. Brick red precipitate = reducing sugar present
Benedict test for non-reducing sugar
. Add Hydorchloric acid to the sample
. HEAT
. Neutralise with sodium hydrogen carbonate
. Can then perform a Benedict test
Test for unknown concentrations
. Carry out a Benedict’s test on known concentrations sugar
. Use a colorimeter to measure the colour of each solution and draw a calibration curve
. Find the concentration of the unknown sample using the calibration curve
Test for starch/Iodine test
. Add two drops of iodine to the sample
. Blue/black colour = present
Test for lipids/emulsion test
. A small amount of sample is placed in 2cm3 of ethanol
. The mixture is shaken so the fat dissolves
. Water is added then the mixture is shaken again
. A white cloudy emulsion = present
Lipid solubility
They are insoluble in water but are soluble in organic solvents like ethanol, acetone and other lipids
Name five roles of lipids
- Make up the membrane
- Source of energy
- Insulation (heat and electrical)
- Protection
- Waterproofing
Triglyceride structure
One molecule of glycerol joined to three fatty acids using an ester bond
Saturated
All the available bonds are used
Unsaturated
Not all available bonds are used
What does an unstaturated fatty acid mean?
The fatty acid chain contains a double bond between the carbon atoms. The molecules can bend so it remains liquid at room temperature
How does the triglyceride structure relate to their properties?
. They contain a lot of energy due to the high ratio of C-H bonds compared to C-C bonds
. Low energy:mass ratio - good as storage
. Compact - more can be stored in the same place
. Large and insoluble in water - doesn’t effect water potential
. High ratio of H:O - important source of water in desert animals
Phospholipid structure
A phosphate group, a glycerol and two fatty acid tails
How does the phospholipid structure relate to its function?
. A hydrophilic head - attracted to water due to the polar nature of the phosphate group
. Hydrophobic fatty acid tails - repelled by water due to the non-polar nature of the tails
